CRUISE REPORT: I01 (Updated JUN 2008) A. HIGHLIGHTS A.1. CRUISE SUMMARY INFORMATION WOCE section designation I01 Expedition designation 316N145_11-12 Chief Scientists Dr. John M. Morrison/NCSU (Leg 1) Dr. Harry L. Bryden/SOC (Leg 2) Dates 1995 AUG 29 - 1995 SEP 28 (Leg 1) 1995 SEP 30 - 1995 OCT 16 (Leg 2) Ship R/V KNORR Ports of call Muscat, Oman to Columbo, Sri Lanka (Leg 1) Columbo, Sri Lanka to Singapore (Leg 2) 22° 28.17 N Station geographic boundaries 43° 41.67 W 97° 33' E 4° 0.30' N Stations 158 Floats and drifters deployed 16 ALACE floats Moorings deployed or recovered 0 Contributing Authors Sarah Zimmerman, Maggie Cook, Marshall Swartz Chief Scientists Contact Information Dr. John M. Morrison Dept. of Marine, Earth and Atmospheric Science • North Carolina State U. 1125 Jordan Hall • Raleigh, North Carolina • 27695-8208 • USA Phone: 919-515-7449 • Email: John_Morrison@NCSU.EDU Dr. Harry L. Bryden Southampton Oceanography Centre • Empress Dock • Southampton S014 3ZH • UK Ph: 44-1703-596436 • Fax: 44-1703-596204 • Email: h.bryden@soc.soton.ac.uk A.2 CRUISE SUMMARY A.2.a Geographic boundaries Cruise Track The cruise went across the North Indian Ocean at a nominal latitude of 8°N. From Muscat, the ship headed for the entrance to the Red Sea before starting the main section off the coast of Somalia. The section across the Arabian Sea ended on the continental shelf of India. After a brief port stop in Colombo, the section was continued from the Sri Lankan continental shelf across the Bay of Bengal and ended on the Myanmar continental shelf. A.2.b Number of Stations A total of 158 hydrographic stations were taken during the cruise, which includes three test stations to check instrument performance. A list of station positions including a brief chronology of notable events is in Table 1. Sampling On each hydrographic station, a continuous CTD profile of temperature, salinity and oxygen versus pressure is measured throughout the water column from the sea surface down to the ocean bottom; 36 water samples are then collected during the upcast and analysed in the laboratory for salinity, oxygen, nutrients (nitrate+nitrite, nitrite, silica and phosphate), chlorofluorocarbons (CFC-11, CFC-12), CO2 components (total CO2 and alkalinity); on selected stations water samples were collected for later analysis for helium, tritium, 14C, 13C and barium; finally, an LADCP was mounted on the CTD/Rosette frame on nearly every station to measure continuous profiles of horizontal velocity from the sea surface to the bottom and back to the sea surface. While underway and on station, continuous measurements were made of bottom depth, surface currents by a ship-mounted ADCP instrument with associated P-code GPS navigation, and meteorological variables with the ship-mounted IMET system. Equipment used aboard KNORR for the basic CTD/Rosette system was provided by both Woods Hole Oceanographic Institution CTD Operations Group, and the Scripps Institution of Oceanography's Shipboard Technical Services/Ocean Data Facility (SIO STS/ODF). Four CTDs were brought for the cruise, two of which were used for the majority of the stations. Underwater equipment included: Primary Sensors: Two Falmouth Scientific (FSI) ICTDs with Sensormedics oxygen sensors. Each has a Sensormedics oxygen sensor assembly and a titanium pressure transducer with temperature monitor. Secondary Sensors: Two Neil Brown Mk-3 CTDs. Each has a Sensormedics oxygen sensor assembly and a titanium pressure transducer with temperature monitor. In addition to the principal section across 8N-10N from Somalia to India, Sri Lanka to Myanmar, this station list contains: 1. a section along the axis of the Gulf of Aden 2. a meridional section across the Gulf of Aden from Yemen coastline 3. a section following German mooring line south of Socotra 4. a short section up onto the Sri Lanka continental shelf near Colombo 5. a short section south of the southern tip of Sri Lanka along 80°E to 4.5°N, repeating I8 stations 6 months later Table 1: Hydrographic Station Positions and Brief Chronology for WOCE Section I1, R/V KNORR, 29 August to 16 October 1995, Muscat to Singapore Sta WOCE Lat Lon Depth Comments CTD # # (N) (E) (m) Used --- ---- ------- ----- ----- ---------------------- ----- Start 23 37 58 38 Muscat Dep 8/29 0600 1 857 22 28 61 12 3215 Station 841 on I7N CTD38 2 858 22 28 61 12 3190 and CTD09 3 859 22 28 61 12 3190 JGOFS station CTD44 4 860 21 35 60 35 Water sample test 300m 5 861 19 05 58 48 3285 Station 808 on I7N 6 862 18 05 58 00 2815 JGOFS station 7 863 16 16 56 33 3710 CTD test CTD09 8 864 14 50 55 25 2440 CTD12 9 865 14 40 54 45 2205 CTD44 10 866 14 30 54 05 2595 11 867 14 20 53 25 2970 Terminated at 700db 12 868 14 20 53 25 2960 ALACE deployed 13 869 14 10 52 45 1880 Terminated at 500bd 14 870 14 10 52 45 1895 CTD38 15 871 14 00 52 10 2195 16 872 13 50 51 30 1790 Repeated as 35 17 873 12 22 43 42 300 Exit of Red Sea 18 874 12 10 44 00 495 19 875 12 00 44 30 1410 20 876 12 10 45 05 815 21 877 12 20 45 45 1390 22 878 12 30 46 25 1770 23 879 12 40 47 00 2005 24 880 12 50 47 40 2350 25 881 13 00 48 20 1995 ALACE deployment 26 882 13 10 48 55 2640 27 883 13 20 49 35 1950 28 884 13 30 50 15 1955 29 885 13 40 50 50 2470 30 886 14 55 50 50 190 Yemen Shelf 31 887 14 49 50 50 560 32 888 14 40 50 50 1230 ALACE deployment 33 889 14 30 50 50 1955 34 890 14 10 51 10 2200 35 891 13 50 51 30 1825 36 892 13 43 51 34 4000 Proceed around Socotra 37 893 10 48 53 22 3905 Pegasus German CTD44 38 894 10 34.2 53 26 4020 mooring K14 39 895 10 21 53 32 4185 Pegasus mooring 40 896 10 09.9 53 38 4280 mooring K15 41 897 9 54 53 48 4460 Pegasus line 42 898 9 38.1 53 56 4580 mooring K16 43 899 9 39 53 19 4580 Test station for CTD12 Sta WOCE Lat Lon Depth Comments CTD # # (N) (E) (m) Used --- ---- ------- ----- ----- ---------------------- ----- 43 900 9 42 51 30 760 Somalia CTD44 44 901 9 35 51 40 1480 Fast ALACE deployment 45 902 9 28 51 50 2325 46 903 9 20 52 00 3650 Fast ALACE deployment 47 904 9 06 52 17 4540 48 905 8 48 52 41 4900 Fast ALACE deployment 49 906 8 30 53 05 5035 50 907 8 30 53 40 4970 51 908 8 30 54 15 5025 mooring K17 8 43,54 20 52 909 8 56 54 25 4800 Halfway between 908+909 53 910 8 30 54 50 4660 54 911 8 30 55 25 4730 Fast ALACE deployment 55 912 8 30 56 00 3800 56 913 8 30 56 35 4380 57 914 8 30 57 10 4385 58 915 8 30 57 34 3105 59 916 8 30 58 06 3905 Section 60 917 8 37 58 24 3700 Perpendicular to 61 918 8 42 58 37 2305 Carlsberg Ridge 62 919 8 51 59 00 3150 ALACE deployment 63 920 8 57 59 14 3525 64 921 9 01 59 25 3615 65 922 9 01 59 57 3540 66 923 9 01 60 29 3345 67 924 9 01 61 01 3965 68 925 9 01 61 33 4380 69 926 9 01 62 05 4530 70 927 9 01 62 37 4545 ALACE deployment 71 928 8 54 63 08 4535 72 929 8 48 63 34 4535 I7 station 782 73 930 8 42 64 00 4530 74 931 8 36 64 26 4560 75 932 8 30 64 52 4550 76 933 8 30 65 23 4535 77 934 8 30 65 53 4525 ALACE deployment 78 935 8 30 66 23 4530 79 936 8 30 66 53 4555 80 937 8 30 67 23 4560 81 938 8 30 67 53 4575 82 939 8 30 68 23 4575 83 940 8 30 68 54 4590 ALACE deployment 84 941 8 30 69 25 4615 Pick up Indian Officer 85 942 8 30 70 00 4465 86 943 8 30 70 35 4165 87 944 8 30 71 10 3910 87 945 8 30 71 45 3475 88 946 8 30 72 05.7 2685 ALACE deployment Sta WOCE Lat Lon Depth Comments CTD # # (N) (E) (m) Used --- ---- ------- ----- ----- ---------------------- ----- 89 947 8 30 72 26 2125 90 948 8 30 72 47 2190 91 949 8 30 73 08 2250 92 950 8 30 73 28 1910 93 951 8 34 73 50 2650 94 952 8 39 74 15 2750 95 953 8 44 74 40 2750 96 954 8 48 75 00 2695 97 955 8 52 75 20 1665 98 956 8 56 75 40 345 99 957 9 00 76 00 95 Way 012 6 58 78 25 Disembark Indian Off 100 958 6 25 79 06 2685 Baldridge station 101 959 6 33 79 18 2345 Baldridge station 102 960 6 42 79 30 1630 Baldridge station 103 961 6 48 79 36 705 Baldridge station Colombo 6 55 79 52 Colombo Arr 9/28 0500 Colombo 6 55 79 52 Colombo Dep 9/30 0300 104 962 5 53 80 00 155 Short Section 105 963 5 49 80 00 1110 Across Boundary 106 964 5 45 80 00 2215 Current South of 107 965 5 40 80 00 3235 Sri Lanka 108 966 5 35 80 00 4030 I8 Station 284 109 967 5 15 80 00 4135 Along 80 E 110 968 4 55 80 00 4225 ALACE in 6C mode water 111 969 4 30 80 00 4285 Down to 4.5°N 112 970 8 31 81 28 55 113 971 8 37 81 36 2695 114 972 8 46 81 48 3740 ALACE deployed 115 973 8 58 82 04 3750 CTD38 116 974 9 13 82 24 3730 CTD44 117 975 9 28 82 44 3695 118 976 9 43 83 04 3650 119 977 9 58 83 24 3620 120 978 9 58 83 51 3610 CTD38 121 979 9 58 84 18 3580 ALACE deployed CTD44 122 980 9 58 84 45 3570 CTD38 123 981 9 58 85 12 3565 124 982 9 13 82 24 3725 Redo 974 125 983 9 28 82 44 3695 Redo 975 126 984 9 43 83 04 3645 Redo 976 127 985 9 58 84 18 3585 Redo 979 128 986 9 58 85 39 3540 129 987 9 58 86 12 3505 130 988 9 58 86 45 3495 131 989 9 50 86 47 3510 I9 station 268 132 990 9 58 87 18 3480 Sta WOCE Lat Lon Depth Comments CTD # # (N) (E) (m) Used --- ---- ------- ----- ----- ---------------------- ----- 133 991 9 58 87 51 3425 ALACE 134 992 9 58 88 24 3405 135 993 9 58 88 57 3375 136 994 9 58 89 28 3350 137 995 9 58 89 59 3310 138 996 9 58 90 30 3330 Pick up Ind. Navy Off 139 997 9 58 91 00 3470 I9 station 234 140 998 9 58 91 27 3405 141 999 9 58 91 54 1285 142 1000 9 58 92 16 845 143 1001 9 58 92 38 990 Ten Degree Channel 144 1002 9 58 93 00 1435 145 1003 9 58 93 22 3065 146 1004 9 58 93 46 4235 147 1005 9 58 94 12 3180 148 1006 9 58 94 38 2855 149 1007 9 54 95 04 1775 Disembark Indian Off 150 1008 9 50 95 30 2620 151 1009 9 50 95 50 2475 152 1010 9 50 96 10 1315 153 1011 9 50 96 30 430 154 1012 9 50 96 55 325 155 1013 9 50 97 17 260 156 1014 9 50 97 33 83 End 1 20 103 50 Singapore Arr10/15 1100 General Oceanics (GO) model 1016-36 pylon with 36-bottle frame with 10-liter bottles manufactured by SIO STS/ODF and Ocean Instrument Systems 10-kHz pinger. A.2.c. Floats: ALACE Deployments Autonomous Lagrangian Circulation Explorer (ALACE) floats are intended to map absolute velocity of large-scale currents for use with geostrophic shears from historical and WOCE Hydrographic Programme sampling. The floats drift at 800 to 1000 m depth, surfacing periodically to report their position by satellite. To avoid diffusion bias, the horizontal coverage is intended to be relatively uniform but the density for this cruise was augmented a bit near the western boundary of the Somalia coast Two floats could not be launched as planned because they were in the territorial waters of India. Permission for such deployments had not been requested from the Government of India and the official Indian observer insisted that no ALACE deployments were allowed. One of the resulting two extra floats was deployed in a thermostad feature south of Sir Lanka at about 1000 m depth at 4 44 N, 80 E. Most of the ALACE floats have a 26-day cycle time, drifting for 26 days at 800 to 1000 m depth, then rising to the sea surface to report position to a satellite, before returning to depth to repeat the cycle for another 26 days. Design lifetime for these floats is 5 years. Four of the ALACE floats deployed in the region of the Somali Current (denoted by "F") have 15-day cycle times. Each ALACE float was prepared in the laboratory during the downcast of a CTD station and launched from the stern of KNORR at the completion of a hydrographic station just as the ship set out for the next station. The launch information is shown in Table 2. TABLE 2: WOCE I1 ALACE FLOAT LAUNCH INFORMATION S/N START TIME OF DEPLOYMENT DEPLOYMENT LAST SELFTEST TIME POSITION ---- ------------- ------------ -------------------- 536 950903 0230Z 950903 0357Z 14:20.03N, 53:25.11E 534 950907 0413Z 950907 0557Z 13:00.34N, 48:19.81E 539 950908 0912Z 950908 1302Z 14:38,08N, 50:49.52E 523F 950912 0944Z 950912 1126Z 09:36,95N, 51:40.11E 521F 950912 1547Z 950912 1944Z 09:21.39N, 51:58.86E 522F 950913 0527Z 950913 0857Z 08:50.95N, 52:41.39E 524F 950914 1555Z 950915 0234Z 08:27.02N, 55:24.39E 540 950916 1452Z 950916 2328Z 09:49.95N, 59:00.22E 546 950918 2142Z 950919 0148Z 09:00.87N, 62:36.73E 545 950921 0131Z 950921 0323Z 08:29.95N, 65:53.15E 542 950922 1955Z 950922 2217Z 08:29.80E, 68:53.85E 541 950924 0841Z 950924 1022Z 08:30.14N, 72:04.99E 543 951001 1615Z 951001 1940Z 04:55.10N, 79:59.93E 544 951003 0318Z 951003 0530Z 08:35.22N, 81:36.64E 533 951005 0413Z 951005 0626Z 09:58.81N, 84:17.46E 532 951008 2001Z 951008 2206Z 09:58.18N, 87:51.67E A.2.d Mooring deployed or recovered A.3 LIST OF PRINCIPLE INVESTIGATORS The list of Principal Investigators, their institution and the measurement program that they are responsible for is shown in Table 3. Table 3: WOCE I1 Principal Investigators Measurement Principal Institution Investigator ------------------------ ---------------- ------------------------------- Chief Scientist John M. Morrison North Carolina State Univ, co-Chief Scientist Harry Bryden Southampton Oceanography Centre Salinity, oxygen, CTD/O2 John Toole Wood Hole Oceanographic Inst. Nutrients Louis Gordon Oregon State Univ. Chlorofluorocarbons Mark Warner Univ. of Washington Shallow He/Tr William Jenkins Wood Hole Oceanographic Inst. Deep He/Tr Zafer Top Univ. of Miami AMS C-14 Robert Key Princeton University Barium Kelly Falkner Oregon State University TCO2 Catherine Goyet Wood Hole Oceanographic Inst. ADCP/LADCP Teresa Chereskin Scripps Inst. of Oceanography Underway PCO2 Robert Key Princeton Univ. IMET Barrie Walden Wood Hole Oceanographic Inst. Thermosalinograph Barrie Walden Wood Hole Oceanographic Inst. ALACE Floats Russ Davis Scripps Inst. of Oceanography A.4 SCIENTIFIC PROGRAMME AND METHODS The transindian hydrographic section I1 is the northernmost of the zonal sections to be carried out during the US WOCE Indian Ocean Expedition in 1994-1996. It crosses the southern boundaries of both the Bay of Bengal in the east and the Arabian Sea in the west. This section effectively completes the circumnavigation of the ocean with high quality hydrographic sections at latitudes between 8°N and 11°N, started by the 10°N transpacific and the 11°N transatlantic section carried out in 1989. Section I1 encloses two areas of the northern Indian Ocean, the Arabian Sea and the Bay of Bengal. From I1 we should be able to compute separate heat, salt and water-mass budgets for each of these basins. This is of interest because the Arabian Sea is an important source of salt to the world ocean, while the Bay of Bengal is an important source of fresh water. In addition to helping define the thermohaline circulation of the Indian Ocean in conjunction with the overall survey of the Indian Ocean Expedition, the specific objectives of the Principal Investigators (PIs) are: 1. To determine the meridional heat and freshwater transports across 8°N in the Indian Ocean and to combine the new estimates with existing Atlantic and Pacific estimates in order to determine the total global ocean heat and freshwater transports across 10°N for comparison with the atmospheric and satellite-based estimates of energy transport; 2. To make a detailed analysis of the freshwater budget of the Bay of Bengal, into which 2 of the world's largest rivers empty, in order to understand the effects of this freshwater source on the Indian Ocean circulation; 3. To estimate the nutrient (and possibly the carbon transport) into and out of the Arabian Sea across its southern boundary at 8°N in order to estimate the size of the overall biological productivity and of the "biological pump" in the Arabian Sea for comparison with JGOFS results. 4. To cooperate with the PIs of the other WOCE Indian Ocean Expedition on the preparation of a new "atlas" describing the first order circulation of the basin and to present and catalog the data collected in a systematic fashion. 5. To coordinate the results of our survey with the JGOFS Arabian Sea Process Study. JGOFS is carrying out 7 cruises within the Arabian Sea, encompassing an entire monsoonal cycle. The JGOFS data will be used to investigate the representativeness of the WOCE sections in the Arabian Sea, where there is large seasonal variability associated with monsoonal forcing. In addition, comparison of data collected during the JGOFS efforts near the mouth of the Arabian Sea with the hydrographic properties at Section I1 may allow us to estimate the percentage of Persian Gulf Water that actually escapes into the Indian Ocean. Finally, estimates of the amount of Arabian Sea Water leaving the basin at the end of the Southwest Monsoon will be made. 6. To determine the extent of eastward penetration of high salinity Arabian Sea waters during the boreal winter that displace the low salinity waters normally carried westward by the North Equatorial Current (NEC). 7. To describe the deep water properties of the Adaman Basin, which is an enclosed basin below approximately 1500 m depth. In addition, there are a number of questions that will be addressed using data from a combination of multiple sections, VOS XBT data, Lagrangian drifter data, etc. We will actively share the I1 measurements with other scientists working on such objectives and questions. Preliminary Results KNORR departed Muscat, Oman, on schedule on 29 August 1995. We proceeded westward down the coast of Oman, reoccupying a joint JGOFS and I7 station (841) at 22° 28' N, 61° 12' E, an I7 station (808) at 19° 05' N, 58° 48' E and a JGOFS station at 18° 05' N, 58° 00' E. Preliminary inter-comparisons of the data show excellent agreement. We then proceeded to carry out our Gulf of Aden Section. This section has 20 stations along a line from 12° 22' N, 43° 44' E to 14° 50' N, 55° 22' E. This section shows considerable variability, but gives us a good endpoint for Red Sea Water for water mass analysis. Satellite imagery from the JGOFS receiving station in Oman will aid in interpreting this data. Because of the threat of pirates, we were forced to cancel the southern half of our planned section across the mouth of the Gulf of Aden. Instead, we proceeded to the position of a German current meter array south of Socotra. Once again because of the threat of pirates, we were forced to cancel any work around the moorings within 60 nm of Socotra. In discussions with Dr. F. Schott via Imarsat, we determined that we were just ahead of METEOR on this section. We coordinated our efforts with Schott to make a more densely spaced section along his array. In addition, we occupied 3 of his Pegasus sites for intercomparison of our LADCP velocities with his Pegasus velocity profiles. We then proceeded to 9° 42' N, 51° 30' E to begin the main I1 line across the Arabian Sea. We took 6 closely spaced stations across the Somali Current, angling down to our main section latitude of 8° 30' N. The main section is across the basin at 8° 30' N, except for a short diagonal section perpendicular to the Carlsberg Ridge at about 58° E and a diversion to reoccupy another I7 station (782) at 8° 48' N, 63° 54'E. On Monday, 18 September, we received word that the Government of India has decided to give a one-time exemption to carry out work in their waters at 20 nm spacing and to allow use of the ADCP and LADCP. Fortunately, the State Department and WOCE Office had been able to give us a heads-up on the clearance about a week earlier. We picked up the Indian Observer at 8° 30' N, 69° 25' E on Saturday, 23 September. We then continued our line through the Laccadive Islands at the 8 Degree Channel and into the coast at 9° 00' N, 76° 00' E. In all we took 58 stations along the main I1 section of which 17 stations were within the Indian EEZ. From the end of the main section, we disembarked the Indian Observer while transiting to Sri Lankan waters. We then reoccupied the 4 inshore stations of the BALDRIDGE I1 Pre- peat section onto the Sri Lankan shelf. We arrived in Colombo, Sri Lanka, on the morning of 28 September, having completed 103 stations on Leg 1. The final station on this leg was WOCE station 961. KNORR departed Colombo, Sri Lanka, on schedule at 0800 on 30 September 1995 and proceeded south of Sri Lanka where 8 stations of Section I8 was reoccupied along 80° E to 4° 30' N. Currents were weak along this section, showing little sign of the Indian Monsoon Current. Time had been scheduled time to occupy 2 stations in the Trincomalee Canyon at about 8° 30' N, 81° 20' E on the coast of Sri Lanka at the request of Kamal Tennakoon of National Aquatic Resources Agency in Sri Lanka. The Sri Lankan Naval Observer informed us that the Tamal Tigers were active in this area and advised us not to take these stations. KNORR then proceeded to the endpoint of the main line at 8° 31' N , 81° 28' E (just off the coast of Sri Lanka). Even though this station was in sight of land in the vicinity of the city of Trincomalee (where there is a major Sri Lankan Naval Base), the Sri Lankan Navy was so concerned about the potential threat of the Tamal Tigers, that they requested that we occupy this station during the daylight hours. They also escorted us with 4 gunboats as we came up the coast from the south to the location of this station. KNORR began the main line across the Bay of Bengal without incident. The first 8 stations were along a SW to NE line from the coast of Sri Lanka to the latitude of the proposed section, 9° 58' N, across the Bay of Bengal. As KNORR proceeded along the main line, a 2 - 3 knot current flowing to the south out to about 75 nm (at least to the 4000 m isobath) was observed in the shipboard ADCP record. We then proceeded along the main line to 9° 58' N, 85° 12' E, where a problem with the CTD occurred. Fortunately, we had been processing the data with about a 24 hour delay. Because we had time, we decided to backtrack and redo 4 of the stations along the main line. We proceeded back to 9° 58' N, 85° 12' E, and continued to the east along the main line. We diverted slightly off the main line to reoccupy I9 Station 268. We picked up the Indian Naval Observer at 9° 58' N, 88° 58' E on Monday morning, 9 October 1995. We then proceeded with our section across the Adaman Sea. The Indian observer disembarked just prior to our entry into the waters of Myanmar. The last 4 stations of the line were within the waters of Myanmar. We completed the section at station 1014 and deadheaded to Singapore, anchoring in the harbour for the night of 15 October 1995 before docking on 16 October. A.5 MAJOR PROBLEMS ENCOUNTERED ON THE CRUISE Because of the threat of pirates, we were forced to cancel the southern half of our planned section across the mouth of the Gulf of Aden. Also, because of the threat of pirates, we were forced to cancel any work around the German current meter moorings within 60 nm of Socotra. Finally, because of the threat of pirates we were not able to begin the section as close to Somalia as we would have liked; our most inshore station was in about 850 meters of water; the ADCP data shows that the most inshore hydrographic station was in the core of the Somali Current; hence we were not able to sample completely across to the inshore side of the Somali Current. Potential problem with Standard Seawater Batch P-124. Suspicion that salinity samples drawn after long times on deck might be changed due to condensation in the warm moist air in the head space of cold, deep-water bottles. LADCP equipment failure for a section of the first leg leaves a portion of the section across the mouth of the Arabian Sea without absolute velocities. A.6 OTHER OBSERVATIONS OF NOTE Preliminary data were supplied to the foreign observers of India, Sri Lanka and Myanmar prior to their departure from the ship. A.7 LIST OF CRUISE PARTICIPANTS Crew List Leg 1 Leg 2 ----------------------------------------- --------- --------- 1. Dr. John Morrison, Co-Chief Scientist CTD Watch CTD Watch North Carolina State University MEAS Box 8208 Raleigh, NC 27695-8208 U. S. Citizen Ph: (919) 515-7449 Fax: (919) 515-7802 Email: John_Morrison@ncsu.edu (PI: Morrison) 2. Vijayakumar Manghnani CTD Watch CTD Watch North Carolina State University MEAS Box 8208 Raleigh, NC 27695-8208 Ph: (919) 515-7449 Fax: (919) 515-7802 Email: vijay@meadsp.nrrc.ncsu.edu (PI: Morrison) 3a. L. V. Gangadhara Rao CTD Watch Physical Oceanography Division National Institute of Oceanography Dona Paula, Goa - 403 004, India Indian Citizen Ph: 91-832-226253 - 56 (O) 91-832-221848 (R) Fax: 91-832-223340 Email: lvgrao@bcgoa.ernet.in Telex: 0194-216 NIO IN (PI: Morrison) 3b. M. T. Babu CTD Watch Physical Oceanography Division National Institute of Oceanography Dona Paula, Goa - 403 004, India Indian Citizen Ph: 91-832-221323 Fax: 91-832-223340 Email: (PI: Morrison) 4. Dr. Harry L. Bryden, Co-Chief Scientist CTD Watch CTD Watch Southampton Oceanography Centre Empress Dock Southampton S014 3ZH, UK U. S. Citizen Ph: 44-1703-596436 Fax: 44-1703-596204 Email: h.bryden@soc.soton.ac.uk (PI: Bryden) 5a. Lisa M. Beal CTD Watch Southampton Oceanography Centre Empress Dock Southampton S014 3ZH, UK U. K. Citizen Ph: 44-1703-596436 Fax: 44-1703-596204 Email: lmb@soc.soton.ac.uk (PI: Bryden) 5b. Dr. Michael N. Tsimplis CTD Watch Southampton Oceanography Centre Empress Dock Southampton S014 3ZH, UK Greek Citizen Ph: 44-1703-596441 Fax: 44-1703-596204 Email: mnt@soc.soton.ac.uk (PI: Bryden) 6a. Alison Scoon CTD Watch 26a Gibbon Road Kingston Upon Thames KT2 6AB, UK Ph: 0181 5415025 or Southampton Oceanography Centre Empress Dock Southampton S014 3ZH, UK c/o Ian Robinson 6b. Michael J. Griffiths CTD Watch Southampton Oceanography Centre Empress Dock Southampton S014 3ZH, UK U. K. Citizen Ph: 44-1703-596436 Fax: 44-1703-596204 Email: m.griffiths@soc.soton.ac.uk (PI: Bryden) 7. Craig Harris CTD Watch CTD Watch Oceanography Laboratories Department of Earth Sciences Liverpool University Liverpool L693BX, UK U. K. Citizen Ph: 44-151-7944097 Email: (PI: Bryden) Crew List Leg 1 Leg 8. Marshall Swartz CTD W Leader CTD W Leader Woods Hole Oceanographic Insitution Woods Hole, MA 02543 U. S. Citizen Ph: (508) 289-2246 Fax: (508) 457-2165 Email: mswartz@whoi.edu (PI: Toole) 9. Paul Robbins CTD W Leader CTD W Leader Woods Hole Oceanographic Insitution Woods Hole, MA 02543 U. S. Citizen Ph: (508) 289-2918 Fax: (508) 457-2181 Email: probbins@whoi.edu (PI: Toole) 10. Laura Goepfert CTD Data Anal CTD Data Anal Woods Hole Oceanographic Insitution Woods Hole, MA 02543 U. S. Citizen Ph: (508) 289-2937 Fax: (508) 457-2165 Email: lgoepfert@whoi.edu (PI: Toole) 11. Paul Bouchard CTD Watch CTD Watch Woods Hole Oceanographic Insitution Woods Hole, MA 02543 U. S. Citizen Ph: (508) 289-3277 Fax: (508) 457-2165 Email: pbouchard@whoi.edu (PI: Toole) 12. George Tupper Salts Salts Woods Hole Oceanographic Insitution Woods Hole, MA 02543 U. S. Citizen Ph: (508) 289-2693 Fax: (508) 457-2165 Email: gtupper@whoi.edu (PI: Toole) 13. Dave Wellwood Dissolved Oxys Dissolved Oxys Woods Hole Oceanographic Insitution Woods Hole, MA 02543 U. S. Citizen Ph: (508) 289-2657 Fax: (508) 457-2165 Email: dwellwood@whoi.edu (PI: Toole) Crew List Leg 1 Leg 2 14. Joe C. Jennings, Jr. Nutrients Nutrients Oregon State University U. S. Citizen Ph: (503) 737-4365 Fax: (503) 737-2064 Email: jenningj@oce.orst.edu (PI: Gordon) 15. Stanley Moore, Jr. Nutrients Nutrients Oregon State University U. S. Citizen Ph: (503) 737-3961 Fax: (503)737-2064 Email: moores@ucs.orst.edu (PI: Gordon) 16. Greg Eischeid CO2 CO2 Woods Hole Oceanographic Institution Woods Hole, MA 02543 U. S. Citizen Ph: (508) 289-3410 Fax: (508) 289-2193 Email: geischeid@whoi.edu (PI: Goyet) 17. Philip Ording CO2 CO2 Woods Hole Oceanographic Institution Woods Hole, MA 02543 U. S. Citizen Ph: (508) 457-2000-3553 Fax: (508) 289-2193 Email: cathy@co2.whoi.edu (PI: Goyet) 18. Toshitaka Amaoka CO2 CO2 Marine and Atmospheric Geochemistry Graduate School of Environmental Earth Science Hokkaido University Sapporo 060, Japan Japanese Citizen Ph: 81-11-706-2371 Fax: 81-11-726-6234 Email: f063411@eoas.hokudai.ac.jp (PI: Goyet) 19. Kozo Okuda CO2 CO2 Marine and Atmospheric Geochemistry Graduate School of Environmental Earth Science Hokkaido University Sapporo 060, Japan Japanese Citizen Ph: 81-11-706-2371 Fax: 81-11-726-6234 Email: f053305@eoas.hokudai.ac.jp (PI: Goyet) 20a. Teri Chereskin ADCP/LADCP Scripps Institute of Oceanography Mail Code 0230 9500 Gilman Drive La Jolla, CA 92093-0230 U. S. Citizen Ph: (619) 543-6368 Fax: Email: teri@scafell.ucsd.edu (PI: Chereskin) 20b. Matthew Trunnell ADCP/LADCP Scripps Institute of Oceanography Mail Code 0230 9500 Gilman Drive La Jolla, CA 92093-0230 U. S. Citizen Ph: (619) 543-5996 Fax: (619) 534-0704 Email: matter@ucsd.edu (PI: Chereskin) 21. Peter Landry He/Tr He/Tr Woods Hole Oceanographic Insitution Woods Hole, MA 02543 U. S. Citizen Ph: (508) 289-2918 Fax: (508) 457-2000-2165 Email: plandry@whoi.edu (PI: Jenkins) 22. Murat Aydin Deep He Deep He c/o Zafer Top RSMAS Univ of Miami 4600 Rickenbaker Causeway Miami, FL 33149 Turkish Citizen Ph: (305) 361-4110 Fax: (305) 361-4112 Email: maydin@rsmas.miami.edu (PI: Top) 23. Steven Covey CFC CFC University of Washington School of Oceanography Box 357940 Seattle, WA 98195-7940 U. S. Citizen Ph: (206) 543-5059 Email: scovey@ocean.washington.edu (PI: Warner) 24a. Sabine Mecking CFC University of Washington School of Oceanography Box 357940 Seattle, WA 98195-7940 German Citizen Email: mecking@ocean.washington.edu (PI: Warner) 24b. Welin Huang CFC University of Washington School of Oceanography Box 357940 Seattle, WA 98195-7940 Email: mwarner@ocean.washington.edu (PI: Warner) 25. Richard Rotter C14 C14 Princeton University U. S. Citizen Ph: (609) 258-3222 Fax: (609) 258-1274 Email: rotter@wiggler.princeton.edu (PI: Key) 26a. CDR M. Sarangapani Observer Oceanographic Forecasting Cell Headquarters Southern Naval Command Naval Base Cochin --- 682004 India Ph: 0484-662472 (O) 0484-662815 (R) (Indian Observer) 26b. LCDR S. Murali Observer Indian Navy Met Officer INS JARAWA c/o Navy Office Port Blair (Observer) 27a. LCDR S. Jayakody Observer/CTD Naval Headquarters P. O. Box 593 Colombo Sri Lanka Ph: 94-1-421151 (Sri Lankan Observer) 27b. LCDR M.R.A.R.B. Mapa Observer/CTD Naval Headquarters P. O. Box 593 Colombo Sri Lanka Ph: 94-1-421151 Fax: 94-1-433896 (Sri Lankan Observer) 28. Tilak Dharmaratne Observer/CO2 Research Officer National Aquatic Resources Agency (NARA) Crow Island Colombo-15 Sri Lanka Ph: 94-1-522932 Fax: 94-1-522932 (Sri Lankan Observer) 29. Dr. San Hla Thaw Observer/CTD Research Officer Department of Meteorology and Hydrology Yangon, Myanmar Ph: 95-1-65669 Fax: 95-1-65944 (Myanmar Observer) 30. Lt. Win Thein Observer/CTD Oceanographic Survey Officer Naval Hydrographic Office Myanmar Navy 55/61 Strand Road Yangon Myanmar Ph: 95-1-95256 (Myanmar Observer) _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ OUTLINE OF DATA PROCESSING DOCUMENTATION INTRODUCTION DATA DOCUMENTATION INSTRUMENT CONFIGURATION ACQUISITION AND PROCESSING METHODS SUMMARY OF LABORATORY CALIBRATIONS FOR CTDs PRESSURE CALIBRATIONS ICTD1338 ICTD1344 PRESSURE BIAS BY STATION NUMBER TEMPERATURE CALIBRATIONS ICTD1338 ICTD1344 SALINITY CALIBRATIONS Table 1 Conductivity coefficients by station number for all stations. SALINITY FITTING RESULTS Figure 1 Leg 1 CTD-bottle salts downtrace stns 878 to 981. Figure 2 Leg 2 CTD-bottle salts downtrace stns 982 to 999. Figure 3 Leg 1 CTD-bottle salts uptrace stns 878 to 981. Figure 4 Leg 2 CTD-bottle salts uptrace stns 982 to 999. OXYGEN CALIBRATIONS SENSOR FAILURES OXYGEN DATA FITTING Table 2 Oxygen fitting coefficients for normal algorithm for all but 53 stations. SPECIAL ALGORITHM FITTING Figure 5 stn 865-869 bottle-CTD oxygen. Figure 6 stn 912-922 bottle-CTD oxygen. Figure 7 stn 912-922 CTD oxygen vs pressure. Figure 8 stn 930-933 CTD oxygen vs pressure. Table 3 Oxygen fitting coefficients for 53 stations using special algorithm. Figure 9 Leg 1 stations (857-961) CTD-bottle oxygen by station and by pressure. Figure 10 Leg 2 stations (962-999) CTD-bottle oxygen by station and by pressure. Figure 11 example of results of oxygen current digitizer change in CTD. Figure 12 stn 978 example of CTD oxygen data quality flag being used. DATA PROCESSING DETAIL NOTES RESOLVED DATA ISSUES EXTRACT OF WATCHSTANDER'S LOG BY STATION NUMBER CRUISE INTERPOLATION DOCUMENTATION POST CRUISE PROCESSING DOCUMENTATION WHPO DATA PROCESSING NOTES WOCE EXPOCODES 316N145-11 (West leg), 316N145-12 (East leg); Knorr Cruise 145 Leg 11; WHOI Internal code "KA45". Document written by Sarah Zimmerman -July 1998; Document revised by Maggie Cook - December 1998. Final version revised by Marshall Swartz - July 1999. INTRODUCTION The WHOI CTD Group supported PIs Harry Bryden and John Morrison in the occupation of WOCE Hydrographic Program line I1 across the N. Indian Ocean from 8/29/95 to 10/16/95. The cruise was conducted as two legs, with stations 857 to 961 done on leg 1 and stations 962 to 1014 occupied on leg 2. Although the cruise completed the planned set of stations, multiple instrumental difficulties and failures plagued the voyage. This report summarizes those problems and outlines the steps taken in the data reduction effort. A synopsis of the instrument problems is given in the ATSEA.DOC. Instrument failures meant that ICTDs from FSI constituted the primary instruments on the I1 cruise, the first time they have been so used by the WHOI Group. In some respects, this cruise highlighted shortcomings in this new instrument. Despite the difficulties, the data set produced by cruise end is of fair quality. Pre-to-post laboratory temperature calibration analyses were quite consistent (differences of only 0.002°C) suggesting the absolute temperatures in the data are reasonable. Calibrated CTD salinity profiles are quite consistent with the water sample salts, with residual salinity discrepancies with pressure between bottles and the profile data ranging between about +0.004 to -0.001 pss with depth. CTD oxygen calibrations are not as good, owing in large part to bad sensor units (that were changed repeatedly during the cruise in search of a well-functioning sensor. The sensor problems have been traced to manufacturing difficulties experienced by the producer combined with the company's poor quality control). Noise levels in the dataset are somewhat larger than scientists are used to working with. A general 0.002 pss salt noise level is present, about a factor of 2 larger than the norm. CTD oxygen noise levels are 0.04ml/l, worsening to 0.06 for individual stations (ship roll/weather or bad sensor?). Between legs 1 and 2, modifications were made to the ICTD giving the oxygen current more resolution. The general noise level was reduced to 0.03ml/l; better, but still slightly higher than the 0.02ml/l noise level typical of the MKIII CTD. DATA DOCUMENTATION Table of CTDs used by station number: ICTD1338: stations 857, 863, 870 through 892, 978, 980 through 1014. ICTD1344: stations 859 through 862, 865 through 869, 893 through 898, 900 through 977 and 979. CTD09: station 858. CTD12: stations 864 and 899. There are no bottle files for stations 858, 867 and 869 due to the pressure signal having dropped out requiring the cast to be aborted. Station 859 has bottles up to 800 dbars only due to fouling of the pylon. Other station by station events are noted in the station by station log (file ATSEA.RPT submitted along with this document). Final processed WOCE-format CTD files are named in the form KA45Dnnn.WC1, where nnn is the station number. Note that stations 000 to 014 are actually stations 1000 through 1014 respectively. Documentation files for this cruise are listed below: I1FINAL.DOC this report. INTERP.DOC list of linear interpolations performed in final processing of the data. ATSEA.DOC a station by station description of CTD issues. Final-revision CTD data files have been submitted with this data report. INSTRUMENT CONFIGURATION: Four CTDs were available on the cruise: two MkIII (CTDs 9 and 12) and two FSI ICTDs (1338 and 1344), with multiple deck units (MkIII and FSI). The CTDs were mounted in an SIO-designed 36-bottle frame fitted with a General Oceanics model 1016-36 36-position rosette pylon, driven through an SIO- modified controller. The MkIII CTDs both experienced failures early in the cruise, making the two FSI ICTDs the primary instruments by default. Roughly 100 stations were made with ICTD 1344 as primary CTD and 50 stations with ICTD 1338 as primary CTD. Most commonly, the underwater frame was set up with two ICTD instruments: one sending data up the wire using its normal FSK configuration, and one set to record data internally, so that at the end of the station the data could be downloaded. Significant signal interaction problems were encountered with the ICTDs and the General Oceanics pylon operating on a 10-km seacable, which resulted in data dropouts from the CTD and loss of confirmation of bottle closure from the pylon. A temporary solution was achieved through electrical modifications to both the CTDs and the pylon deck controller to accommodate the long seacable, and data quality improved substantially. ACQUISITION AND PROCESSING METHODS Data from ICTD1338 were acquired at 26.0 Hz and processed with a temperature lag of 630 ms. Data from ICTD 1344 were acquired at 26.0 Hz and with a temperature lag of 500 ms. The temperature lag was checked by comparing density reversals in theta salinity (TS) plots (Giles and McDonald, 1986). It was found that the aforementioned lags showed the least amount of looping or density reversals. For the first 9 stations (857-865) CTD data were acquired using an FSI DT- 1050 deck unit to demodulate the data. From station 866 and beyond, data were acquired by an EG&G Mk-III deck unit to demodulate the data. The deck units fed serial data to two personal computers running EG&G version 5.2 rev. 2 CTD acquisition software (EG&G, Oceansoft Acquisition Manual, 1990), one providing graphical data to screen and plotter, and the other a running listing output. Approach to seafloor of the CTD package was controlled by monitoring the pinger trace made by the direct and bottom return signals on the ship-provided PDR. After each station, the CTD data were forwarded to another set of personal computers running both EG&G CTD post-processing 5.2 rev. 2 software and custom-built software from WHOI (Millard and Yang, 1993). The data were first-differenced, lag corrected, pressure sorted, and centered into 2 dbar bins for final data quality control and analysis, including fitting to water sample salinity and oxygen results. SUMMARY OF LABORATORY CALIBRATIONS FOR CTDs Maren Tracy Plueddemann and Marshall Swartz calibrated the pressure, temperature, and conductivity sensors at the Woods Hole Oceanographic Institution CTD Calibration Laboratory pre and post-cruise. The results are given below. LABORATORY PRESSURE CALIBRATIONS ICTD 1338: PRE CRUISE CAL Date: August 1995 Notes: 1338 and 1344 kept together in cold bath for pressure calibration. 1338, 1344 and CTD1 received temperature calibration at same time. Bath temperature during pressure calibration = 1.85 deg C Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = 0.337188E+01 B = 0.100040E+00 C = -0.989186E-08 D = 0.121806E-12 Standard deviation of fit = 0.757851E+00 POST CRUISE CAL Date: November 1995 Notes: 1338 and 1344 received pressure and temperature calibrations at the same time. Bath temperature during pressure calibration = 1.67 deg C Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = 0.299558E+01 B = 0.999477E-01 C = -0.646358E-08 D = 0.900392E-13 Standard deviation of fit = 0.635441E+00 Bath temperature during pressure calibration = 29.80 deg C Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = 0.300466E+01 B = 0.999851E-01 C = -0.785380E-08 D = 0.103497E-12 Standard deviation of fit = 0.740938E+00 COMBINED PRE- and POST-CRUISE CAL • Due to pressure bias shifts, a combination of the pre- and post- cruise pressure calibrations was selected for post cruise processing. Bath temperature during pressure calibrations were 1.85 and 1.67 deg C Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = 0.326823E+01 B = 0.999882E-01 C = -0.798407E-08 D = 0.103679E-12 Standard deviation of fit = 0.766984E+00 ICTD 1344: PRE CRUISE CAL Date: August 1995 Notes: 1338 and 1344 kept together in cold bath for pressure calibration. 1338, 1344 and CTD1 received temperature calibration at same time. Bath temperature during pressure calibration = 1.85 deg C Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = 0.203003E+01 B = 0.999794E-01 C = -0.166617E-08 D = 0.175895E-13 Standard deviation of fit = 0.490572E+00 POST CRUISE CAL Date: November 1995 • This post cruise calibration was selected for post-cruise processing. Notes: 1338 and 1344 received pressure and temperature calibrations at the same time. Bath temperature during pressure calibration = 1.67 deg C Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = 0.162374E+01 B = 0.999549E-01 C = -0.293230E-09 D = 0.372714E-14 Standard deviation of fit = 0.341575E+00 Bath temperature during pressure calibration = 29.80 deg C Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = 0.167806E+01 B = 0.999615E-01 C = -0.720102E-09 D = 0.938970E-14 Standard deviation of fit = 0.462750E+00 PRESSURE BIAS BY STATION NUMBER: The following table summarizes the pressure bias applied during post-cruise data-processing, based upon the pressure measured by the CTD immediately prior to entering the water and immediately following recovery from the water. sta ctd# bias_down bias_up sta ctd# bias_down bias_up --- ---- ------------ ------------ --- ---- ------------ ------------ 857 1338 0.296823E+01 0.296823E+01 897 1344 0.143003E+01 0.143003E+01 858 09 -.452144E+01 -.452144E+01 898 1344 0.113003E+01 0.113003E+01 859 1344 0.183003E+01 0.183003E+01 899 12 -.381194E+02 -.381194E+02 860 1344 0.223003E+01 0.223003E+01 900 1344 0.133003E+01 0.133003E+01 861 1344 0.243003E+01 0.243003E+01 901 1344 0.153003E+01 0.153003E+01 862 1344 0.233003E+01 0.233003E+01 902 1344 0.143003E+01 0.143003E+01 863 1338 -.442144E+01 -.442144E+01 903 1344 0.153003E+01 0.153003E+01 864 12 -.391194E+02 -.391194E+02 904 1344 0.143003E+01 0.143003E+01 865 1344 0.233003E+01 0.233003E+01 905 1344 0.123003E+01 0.123003E+01 866 1344 0.203003E+01 0.203003E+01 906 1344 0.113003E+01 0.113003E+01 867 1344 0.223003E+01 0.223003E+01 907 1344 0.113003E+01 0.113003E+01 868 1344 0.193003E+01 0.193003E+01 908 1344 0.123003E+01 0.123003E+01 869 1344 0.213003E+01 0.213003E+01 909 1344 0.300300E-01 0.300300E-01 870 1338 0.216823E+01 0.216823E+01 910 1344 0.133003E+01 0.133003E+01 871 1338 0.266823E+01 0.266823E+01 911 1344 0.930030E+00 0.930030E+00 872 1338 0.256823E+01 0.256823E+01 912 1344 0.113003E+01 0.113003E+01 873 1338 0.246823E+01 0.246823E+01 913 1344 0.830030E+00 0.830030E+00 874 1338 0.256823E+01 0.256823E+01 914 1344 0.830030E+00 0.830030E+00 875 1338 0.276823E+01 0.276823E+01 915 1344 0.830030E+00 0.830030E+00 876 1338 0.246823E+01 0.246823E+01 916 1344 0.113003E+01 0.113003E+01 877 1338 0.256823E+01 0.256823E+01 917 1344 0.123003E+01 0.123003E+01 878 1338 0.246823E+01 0.246823E+01 918 1344 0.930030E+00 0.930030E+00 879 1338 0.276823E+01 0.276823E+01 919 1344 0.123003E+01 0.123003E+01 880 1338 0.226823E+01 0.226823E+01 920 1344 0.123003E+01 0.123003E+01 881 1338 0.246823E+01 0.246823E+01 921 1344 0.630030E+00 0.630030E+00 882 1338 0.276823E+01 0.276823E+01 922 1344 0.113003E+01 0.113003E+01 883 1338 0.226823E+01 0.226823E+01 923 1344 0.113003E+01 0.113003E+01 884 1338 0.206823E+01 0.206823E+01 924 1344 0.630030E+00 0.630030E+00 885 1338 0.196823E+01 0.196823E+01 925 1344 0.630030E+00 0.630030E+00 886 1338 0.266823E+01 0.266823E+01 926 1344 0.730030E+00 0.730030E+00 887 1338 0.226823E+01 0.226823E+01 927 1344 0.630030E+00 0.630030E+00 888 1338 0.216823E+01 0.216823E+01 928 1344 0.730030E+00 0.730030E+00 889 1338 0.216823E+01 0.216823E+01 929 1344 0.830030E+00 0.830030E+00 890 1338 0.196823E+01 0.196823E+01 930 1344 0.930030E+00 0.930030E+00 891 1338 0.196823E+01 0.196823E+01 931 1344 0.930030E+00 0.930030E+00 892 1338 0.196823E+01 0.196823E+01 932 1344 0.930030E+00 0.930030E+00 893 1344 0.183003E+01 0.183003E+01 933 1344 0.430030E+00 0.430030E+00 894 1344 0.163003E+01 0.163003E+01 934 1344 0.630030E+00 0.630030E+00 895 1344 0.123003E+01 0.123003E+01 935 1344 0.630030E+00 0.630030E+00 896 1344 0.103003E+01 0.103003E+01 936 1344 0.630030E+00 0.630030E+00 sta ctd# bias_down bias_up sta ctd# bias_down bias_up --- ---- ------------ ------------ --- ---- ------------ ------------ 937 1344 0.330030E+00 0.330030E+00 976 1344 0.730030E+00 0.730030E+00 938 1344 0.630030E+00 0.630030E+00 977 1344 0.103003E+01 0.103003E+01 939 1344 0.830030E+00 0.830030E+00 978 1338 0.266823E+01 0.266823E+01 940 1344 0.730030E+00 0.730030E+00 979 1344 0.133003E+01 0.133003E+01 941 1344 0.730030E+00 0.730030E+00 980 1338 0.296823E+01 0.296823E+01 942 1344 0.830030E+00 0.830030E+00 981 1338 0.206823E+01 0.206823E+01 943 1344 0.830030E+00 0.830030E+00 982 1338 0.276823E+01 0.276823E+01 944 1344 0.730030E+00 0.730030E+00 983 1338 0.276823E+01 0.276823E+01 945 1344 0.830030E+00 0.830030E+00 984 1338 0.276823E+01 0.276823E+01 946 1344 0.630030E+00 0.630030E+00 985 1338 0.256823E+01 0.256823E+01 947 1344 0.230030E+00 0.230030E+00 986 1338 0.226823E+01 0.226823E+01 948 1344 0.630030E+00 0.630030E+00 987 1338 0.176823E+01 0.176823E+01 949 1344 0.530030E+00 0.530030E+00 988 1338 0.266823E+01 0.266823E+01 950 1344 0.430030E+00 0.430030E+00 989 1338 0.256823E+01 0.256823E+01 951 1344 0.930030E+00 0.930030E+00 990 1338 0.266823E+01 0.266823E+01 952 1344 0.930030E+00 0.930030E+00 991 1338 0.256823E+01 0.256823E+01 953 1344 0.103003E+01 0.103003E+01 992 1338 0.256823E+01 0.256823E+01 954 1344 0.113003E+01 0.113003E+01 993 1338 0.256823E+01 0.256823E+01 955 1344 0.730030E+00 0.730030E+00 994 1338 0.246823E+01 0.246823E+01 956 1344 0.930030E+00 0.930030E+00 995 1338 0.246823E+01 0.246823E+01 957 1344 0.113003E+01 0.113003E+01 996 1338 0.246823E+01 0.246823E+01 958 1344 0.103003E+01 0.103003E+01 997 1338 0.246823E+01 0.246823E+01 959 1344 0.930030E+00 0.930030E+00 998 1338 0.236823E+01 0.236823E+01 960 1344 0.113003E+01 0.113003E+01 999 1338 0.236823E+01 0.236823E+01 961 1344 0.530030E+00 0.530030E+00 000 1338 0.236823E+01 0.236823E+01 962 1344 0.143003E+01 0.143003E+01 001 1338 0.246823E+01 0.246823E+01 963 1344 0.103003E+01 0.103003E+01 002 1338 0.256823E+01 0.256823E+01 964 1344 0.133003E+01 0.133003E+01 003 1338 0.256823E+01 0.256823E+01 965 1344 0.103003E+01 0.103003E+01 004 1338 0.256823E+01 0.256823E+01 966 1344 0.133003E+01 0.133003E+01 005 1338 0.196823E+01 0.196823E+01 967 1344 0.930030E+00 0.930030E+00 006 1338 0.186823E+01 0.186823E+01 968 1344 0.830030E+00 0.830030E+00 007 1338 0.196823E+01 0.196823E+01 969 1344 0.830030E+00 0.830030E+00 008 1338 0.206823E+01 0.206823E+01 970 1344 0.133003E+01 0.133003E+01 009 1338 0.196823E+01 0.196823E+01 971 1344 0.143003E+01 0.143003E+01 010 1338 0.196823E+01 0.196823E+01 972 1344 0.153003E+01 0.153003E+01 011 1338 0.196823E+01 0.196823E+01 973 1344 0.430030E+00 0.430030E+00 012 1338 0.196823E+01 0.196823E+01 974 1344 0.133003E+01 0.133003E+01 013 1338 0.196823E+01 0.196823E+01 975 1344 0.103003E+01 0.103003E+01 014 1338 0.196823E+01 0.196823E+01 LABORATORY TEMPERATURE CALIBRATIONS ICTD 1338 had a small change, less than 0.002 deg C. The pre and post temperature calibrations were averaged to be used with the post cruise processing. The ICTD 1344 temperature calibration changed pre to post cruise with a bias shift of +0.002 deg C. CTD reading warmer at the post cruise calibration. The point at where the temperature shift occurred was looked for but not found. The most reliable search was to look at data from the same station where both primary and internal recording CTDs were used. They did not show where the jump occurred. The fast thermistor channel data were also compared at points where the salinity calibration changed. There was not enough proof to point to a spot where the jump occurred, so an average of the pre and post cruise calibrations was used to process the data. ICTD 1338 SLOW PLATINUM THERMOMETER CHANNEL PRE CRUISE CAL Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = 0.285975E-02 B = 0.500231E-03 C = -0.177714E-10 D = 0.194501E-15 Standard deviation of fit = 0.373642E-03 POST CRUISE CAL Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = 0.918509E-03 B = 0.500358E-03 C = -0.190649E-10 D = 0.192328E-15 Standard deviation of fit = 0.352686E-03 COMBINED PRE AND POST CRUISE CAL • A combined calibration was used for post cruise processing as noted above. Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = 0.186857E-02 B = 0.500298E-03 C = -0.185827E-10 D = 0.195224E-15 Standard deviation of fit = 0.594841E-03 ICTD 1338 FAST THERMISTOR CHANNEL Note: ICTD1338 fast thermistor temperature data was used to check for temperature shifts during cruise, but did not contribute to the final processed temperature data. PRE CRUISE CAL Note: the second order fit was used during the cruise. The third order fit was used post cruise to compare changes pre to post cruise for the fast thermistor channel. Resulting polynomial coefficients for a second order fit: (A+Bx+Cx^2): A = 0.915609E-01 B = 0.495852E-03 C = 0.333829E-10 Standard deviation of fit = 0.693632E-01 Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = -0.187870E-01 B = 0.524023E-03 C = -0.116195E-08 D = 0.129201E-13 Standard deviation of fit = 0.168422E-02 POST CRUISE CAL Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = -0.186425E-01 B = 0.524085E-03 C = -0.116322E-08 D = 0.129201E-13 Standard deviation of fit = 0.175345E-02 ICTD 1338 OXYGEN TEMPERATURE CHANNEL PRE CRUISE CAL Resulting polynomial coefficients for a second order fit: (A+Bx+Cx^2): A = -0.216281E+01 B = 0.160633E+00 C = -0.121723E-03 Standard deviation of fit = 0.158769E+00 POST CRUISE CAL This post-cruise calibration was used with the oxygen algorithms to produce the final dataset. Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = -0.277188E+01 B = 0.183254E+00 C = -0.324103E-03 D = 0.503239E-06 Standard deviation of fit = 0.361886E-01 ICTD 1344 SLOW PLATINUM THERMOMETER PRE CRUISE CAL Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = -0.639595E-02 B = 0.500576E-03 C = -0.219271E-10 D = 0.227245E-15 Standard deviation of fit = 0.260050E-03 POST CRUISE CAL Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A =-0.853971E-02 B = 0.500625E-03 C = -0.235555E-10 D = 0.243046E-15 Standard deviation of fit = 0.668181E-03 COMBINED PRE AND POST CRUISE CAL • A combined calibration was used for final post cruise processing. Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = -0.748166E-02 B = 0.500600E-03 C = -0.226875E-10 D = 0.234567E-15 Standard deviation of fit = 0.940009E-03 ICTD 1344 FAST PLATINUM THERMOMETER CHANNEL Note: The fast platinum thermometer channel was used as a secondary reference to judge changes to the ICTD 1344 slow platinum thermometer channel during the cruise. These measurements did not contribute to the final processed data. PRE CRUISE CAL Resulting polynomial coefficients for a second order fit: (A+Bx+Cx^2): A = -0.164421E-02 B = 0.499960E-03 C = 0.832749E-12 Standard deviation of fit = 0.146257E-02 Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = -0.390910E-02 B = 0.500535E-03 C = -0.235454E-10 D = 0.263094E-15 Standard deviation of fit = 0.356128E-03 POST CRUISE CAL Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = -0.707179E-02 B = 0.500630E-03 C = -0.267632E-10 D = 0.294216E-15 Standard deviation of fit = 0.585656E-03 ICTD 1344 FAST THERMISTOR CHANNEL Note: ICTD1344 fast thermistor temperature data was used to check for temperature shifts during cruise, but did not contribute to the final processed temperature data. PRE CRUISE CAL Resulting polynomial coefficients for a second order fit: (A+Bx+Cx^2): A = 0.889859E-01 B = 0.496237E-03 C = 0.282361E-10 Standard deviation of fit = 0.677849E-01 Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = -0.188737E-01 B = 0.523767E-03 C = -0.113985E-08 D = 0.126255E-13 Standard deviation of fit = 0.182910E-02 POST CRUISE CAL Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = -0.181959E-01 B = 0.523798E-03 C = -0.113971E-08 D = 0.126209E-13 Standard deviation of fit = 0.171024E-02 ICTD 1344 OXYGEN TEMPERATURE CHANNEL PRE CRUISE CAL Resulting polynomial coefficients for a second order fit: (A+Bx+Cx^2): A = -0.336502E+01 B = 0.146252E+00 C = -0.637599E-04 Standard deviation of fit = 0.293626E+00 POST CRUISE CAL • The post-cruise oxygen temperature calibration was used with the oxygen algorithms for the final dataset. Resulting polynomial coefficients for a third order fit: (A+Bx+Cx^2+Dx^3): A = -0.477833E+01 B = 0.194995E+00 C = -0.466521E-03 D = 0.921395E-06 Standard deviation of fit = 0.714265E-01 SALINITY CALIBRATIONS The CTD conductivity sensor data were fit to the water sample conductivity as described in Millard and Yang (1993). The stations were fit by groups according to the drift of the conductivity sensor over time. Plot results of deep water theta/S revealed that there was a difference between CTDs: 1338: *.PRS CTD salt read too high ~0.002 psu or temperature was too low compared to *.SEA file. 1344: *.PRS CTD salt read too low ~0.001 psu or temperature was too high compared to *.SEA file. The consistency of the bias between stations indicates it was probably not a real ocean measurement such as measuring internal waves, but some kind of instrument, package dynamic or bottle artifact. All ICTD 1338 stations have a significant bias, with the downtrace always saltier than the bottles. The uptrace has been fit well, but the uptrace is fresher than the downtrace. To correct for the difference, the downtrace salinity data for the group of stations 978 and 980 through 1014 were fit to the bottle data. This was accomplished by processing the 2-decibar averaged downtrace CTD data against the bottle data, and provided a more acceptable fit for these stations. Figures 1 and 2 demonstrate the CTD salt to bottle salt fits for stations 982 through 1000 using downtrace data, and figures 3 and 4 demonstrate the same fits using uptrace data as is normally done. ICTD 1338 stations 870 through 892 seemed to fit well after forcing the CTD salt data to agree with the bottom bottle data, and so were not refit using the downtrace. ICTD 1344 downtraces trend toward being fresher than the bottles. The uptrace and downtrace agree, but the fits were not working well. Some of the fits were recalculated, with emphasis on matching up the CTD and salts in the bottom water. CTD comparisons were made with the primary CTD and memory CTD data from the same stations. Pressure agreed very well, with bottom depths agreeing within 1dbar on the stations checked. Temperature would stray, +/-.002 at the bottom, sometimes ICTD 1338 being warmer, and sometimes ICTD 1344 was warmer. This is most likely a factor of the location of the telemetering CTD on the sampler frame being different than the position of the memory mode CTD and thus in a different waterpath. Both CTDs could have thermal contamination of the temperature signal from the frame while sampling at a bottle stop. Notes for particular stations' salinity calibrations Stations 936-938, 940-941: A pressure dependent difference between bottle and CTD salinities could not be removed without changing the conductivity cell geometry correction terms for pressure (ALPHA) and temperature (BETA). After station 942, the conductivity cell was cleaned due to slime buildup. The difficult calibrations from stations 936 to 942 could have been induced by fouling or buildup of slime on the conductivity cell. Stations 936, 937 and 938: BETA was changed from 1.5e-8 to 0.75e-8 Stations 940 and 941 have BETA changed from 1.5e-8 to 0.75e-8, and ALPHA changed from -6.5e-6 to -9.75e-6. Station 923 and 954: Salt changes that looked questionable until the uptrace was overlaid and followed the shape of the downtrace. Station 923 freshens around 2 deg C. Station 954 has spikes and a shift at 1750dbar, 1900dbar and 2250 dbar that are clearly repeated in the uptrace. Table 1: Final conductivity coefficients applied by station number. The coefficients used to scale downtrace conductivity data for the I1 stations are listed below. stn bias slope stn bias slope --- ------------ ------------ --- ------------ ------------ 857 0.269148E-02 0.999756E-03 896 -.823240E-03 0.999989E-03 858 0.148422E-01 0.997105E-03 897 -.823240E-03 0.999989E-03 859 0.758850E-02 0.999569E-03 898 -.823240E-03 0.999989E-03 860 0.758850E-02 0.999569E-03 899 0.187740E-01 0.100097E-02 861 0.758850E-02 0.999569E-03 900 -.823240E-03 0.999992E-03 862 0.758850E-02 0.999569E-03 901 -.823240E-03 0.999992E-03 863 0.269148E-02 0.999816E-03 902 -.823240E-03 0.999992E-03 864 0.187740E-01 0.100097E-02 903 -.823240E-03 0.999992E-03 865 0.758850E-02 0.999569E-03 904 -.823240E-03 0.999992E-03 866 0.758850E-02 0.999569E-03 905 -.823240E-03 0.999992E-03 867 0.758850E-02 0.999569E-03 906 -.823240E-03 0.999992E-03 868 0.758850E-02 0.999649E-03 907 -.823240E-03 0.999992E-03 869 0.758850E-02 0.999569E-03 908 -.823240E-03 0.999992E-03 870 0.269148E-02 0.999795E-03 909 -.823240E-03 0.999989E-03 871 0.269148E-02 0.999795E-03 910 -.106344E-02 0.100004E-02 872 0.269148E-02 0.999795E-03 911 -.106344E-02 0.100004E-02 873 0.269148E-02 0.999795E-03 912 -.106344E-02 0.100004E-02 874 0.269148E-02 0.999795E-03 913 -.106344E-02 0.100004E-02 875 0.269148E-02 0.999795E-03 914 -.106344E-02 0.100004E-02 876 0.269148E-02 0.999795E-03 915 -.106344E-02 0.100004E-02 877 0.269148E-02 0.999795E-03 916 -.106344E-02 0.100004E-02 878 0.269148E-02 0.999795E-03 917 -.106344E-02 0.100004E-02 879 0.269148E-02 0.999795E-03 918 -.128407E-03 0.100004E-02 880 0.269148E-02 0.999795E-03 919 -.128407E-03 0.100004E-02 881 0.269148E-02 0.999795E-03 920 -.128407E-03 0.100004E-02 882 0.269148E-02 0.999795E-03 921 -.128407E-03 0.100004E-02 883 0.269148E-02 0.999795E-03 922 -.128407E-03 0.100004E-02 884 0.269148E-02 0.999795E-03 923 -.128407E-03 0.100004E-02 885 0.269148E-02 0.999795E-03 924 -.128407E-03 0.100004E-02 886 0.269148E-02 0.999795E-03 925 -.128407E-03 0.100004E-02 887 0.269148E-02 0.999795E-03 926 -.128407E-03 0.100004E-02 888 0.269148E-02 0.999795E-03 927 -.128407E-03 0.100004E-02 889 0.269148E-02 0.999795E-03 928 -.128407E-03 0.100004E-02 890 0.269148E-02 0.999795E-03 929 -.296800E-03 0.100006E-02 891 0.269148E-02 0.999795E-03 930 -.296800E-03 0.100006E-02 892 0.269148E-02 0.999795E-03 931 -.296800E-03 0.100006E-02 893 -.823240E-03 0.999989E-03 932 -.296800E-03 0.100006E-02 894 -.823240E-03 0.999989E-03 933 -.296800E-03 0.100006E-02 895 -.823240E-03 0.999989E-03 934 -.296800E-03 0.100014E-02 stn bias slope stn bias slope --- ------------ ------------ --- ------------ ------------ 935 -.296800E-03 0.100006E-02 975 -.519660E-02 0.100019E-02 936 0.141056E-02 0.100005E-02 976 -.519660E-02 0.100019E-02 937 0.141056E-02 0.100005E-02 977 -.390173E-02 0.100007E-02 938 0.141056E-02 0.100005E-02 978 0.419290E-03 0.999988E-03 939 0.141056E-02 0.100005E-02 979 -.390173E-02 0.100015E-02 940 -.514493E-02 0.100032E-02 980 0.419290E-03 0.999994E-03 941 -.514493E-02 0.100032E-02 981 0.419290E-03 0.999994E-03 942 -.514493E-02 0.100030E-02 982 0.419290E-03 0.999994E-03 943 -.891709E-03 0.100003E-02 983 0.419290E-03 0.999994E-03 944 -.891709E-03 0.100003E-02 984 0.419290E-03 0.999994E-03 945 -.891709E-03 0.100003E-02 985 0.419290E-03 0.999994E-03 946 -.891709E-03 0.100004E-02 986 0.419290E-03 0.999994E-03 947 -.891709E-03 0.100004E-02 987 0.419290E-03 0.999994E-03 948 -.891709E-03 0.100004E-02 988 0.419290E-03 0.999994E-03 949 -.891709E-03 0.100004E-02 989 0.419290E-03 0.999994E-03 950 -.891709E-03 0.100004E-02 990 0.419290E-03 0.999994E-03 951 -.891709E-03 0.999983E-03 991 0.419290E-03 0.999994E-03 952 -.891709E-03 0.100004E-02 992 0.419290E-03 0.999994E-03 953 -.891709E-03 0.100004E-02 993 0.419290E-03 0.999994E-03 954 -.891709E-03 0.100004E-02 994 0.419290E-03 0.999994E-03 955 -.891709E-03 0.100004E-02 995 0.419290E-03 0.999994E-03 956 -.891709E-03 0.100004E-02 996 0.419290E-03 0.999994E-03 957 -.891709E-03 0.100004E-02 997 0.419290E-03 0.999994E-03 958 -.891709E-03 0.999997E-03 998 0.419290E-03 0.999994E-03 959 -.891709E-03 0.100004E-02 999 0.419290E-03 0.999994E-03 960 -.891709E-03 0.100008E-02 000 0.419290E-03 0.999994E-03 961 -.891709E-03 0.100008E-02 001 0.419290E-03 0.999994E-03 962 -.390173E-02 0.100009E-02 002 0.419290E-03 0.999994E-03 963 -.390173E-02 0.100009E-02 003 0.419290E-03 0.999994E-03 964 -.519660E-02 0.100021E-02 004 0.419290E-03 0.999994E-03 965 -.519660E-02 0.100021E-02 005 0.419290E-03 0.999994E-03 966 -.519660E-02 0.100021E-02 006 0.419290E-03 0.999994E-03 967 -.519660E-02 0.100021E-02 007 0.419290E-03 0.999994E-03 968 -.519660E-02 0.100021E-02 008 0.419290E-03 0.999994E-03 969 -.519660E-02 0.100021E-02 009 0.419290E-03 0.999994E-03 970 -.519660E-02 0.100019E-02 010 0.419290E-03 0.999994E-03 971 -.519660E-02 0.100019E-02 011 0.419290E-03 0.999994E-03 972 -.519660E-02 0.100019E-02 012 0.419290E-03 0.999994E-03 973 -.519660E-02 0.100019E-02 013 0.419290E-03 0.999994E-03 974 -.519660E-02 0.100019E-02 014 0.419290E-03 0.999994E-03 The coefficients used to scale uptrace conductivity data for selected I1 stations are listed below. stn bias slope stn bias slope --- ------------ ------------ --- ------------ ------------ 978 0.216462E-02 0.999940E-03 997 0.216462E-02 0.999975E-03 980 0.216462E-02 0.999940E-03 998 0.216462E-02 0.999975E-03 981 0.216462E-02 0.999940E-03 999 0.216462E-02 0.999975E-03 982 0.216462E-02 0.999940E-03 000 0.216462E-02 0.999975E-03 983 0.216462E-02 0.999975E-03 001 0.216462E-02 0.999975E-03 984 0.216462E-02 0.999975E-03 002 0.216462E-02 0.999975E-03 985 0.216462E-02 0.999975E-03 003 0.216462E-02 0.999975E-03 986 0.216462E-02 0.999975E-03 004 0.216462E-02 0.999975E-03 987 0.216462E-02 0.999975E-03 005 0.216462E-02 0.999975E-03 988 0.216462E-02 0.999975E-03 006 0.216462E-02 0.999975E-03 989 0.216462E-02 0.999975E-03 007 0.216462E-02 0.999975E-03 990 0.216462E-02 0.999975E-03 008 0.216462E-02 0.999975E-03 991 0.216462E-02 0.999975E-03 009 0.216462E-02 0.999975E-03 992 0.216462E-02 0.999975E-03 010 0.216462E-02 0.999975E-03 993 0.216462E-02 0.999975E-03 011 0.216462E-02 0.999975E-03 994 0.216462E-02 0.999975E-03 012 0.216462E-02 0.999975E-03 995 0.216462E-02 0.999975E-03 013 0.216462E-02 0.999975E-03 996 0.216462E-02 0.999975E-03 014 0.216462E-02 0.999975E-03 Note: Uptrace CTD conductivity data was fit to the bottle salts for stations 978 and 980 through 1014 as described in the preceding documentation to achieve a better fit. SALINITY FITTING RESULTS: The following plots show the differences between the rosette and CTD salts across legs one and two. It is important to note that these plots cover both CTDs, each of which were opened on several occasions potentially causing calibration changes. In the beginning of the cruise many mechanical problems were encountered. (see ATSEA.doc). Figure 1: Leg 1 - Difference between calibrated downtrace CTD salts and the rosette salinity data Figure 2: Leg 2 - Difference between calibrated downtrace CTD salts and rosette salinity data Figure 3: Leg 1 Differences between calibrated uptrace CTD salts in rosette file (scaled with separate multiple regression fit from down salinities) and rosette salts. Note that the residuals are significantly better for the uptrace data. Fits to the uptrace data were applied to the uptrace CTD data in the rosette file. Due to hysteresis, fits to the downtrace data needed to be applied to the downtrace CTD data files for stations 978 to 1014. Figure 4: Leg 2: Differences between scaled uptrace CTD salts in the rosette file (separate multiple regression fit from down salinities) and the rosette salt data. OXYGEN CALIBRATIONS: SENSOR FAILURES The CTD oxygen data presented special problems from the beginning. While all four CTDs were initially fitted with new oxygen sensors, and spares were brought on the cruise, the stations were plagued with sensor failures and erratic sensor data. The CTDs all used Sensormedics brand polarographic oxygen sensors, and due to recent experience of failures, it was expected that sensor changes would have to be made. However, the failure rate exceeded our low expectations, with seven replacement sensors being used. Oxygen sensors were replaced following the stations listed below: Station CTD Sensor s/n ------- ---- ---------- 865 1344 5-06-03 910 1344 5-06-02 923 1344 5-07-02 930 1344 4-10-2 980 1344 4-12-04 991 1344 5-06-01 The CTDs used interchangeable sensor assemblies, which permitted the oxygen thermistor and sensor module to simply be unplugged and a new one installed if a problem was found. This speeded up the changeout of failed oxygen sensors. However, since each CTD's oxygen temperature channel is calibrated to a specific module, swapping a module out changes the oxygen temperature calibration. Due to the large number of failures of sensors, modules were interchanged between the ICTDs on several occasions, and necessitated special attention to fitting of the data. OXYGEN DATA FITTING Some stations fit well using normal fitting routines, while others had a definite pressure dependent shape in the residuals. A similar shape recurred in different groups. The shape was more pronounced in some groups than others. A weight of 0.8 and lag of 1 was consistent from a few of the larger groups. Most of the groups had this weight and lag held during the fits since many groups came up with weights over 1 and lags below 0 when allowed to fit for those parameters. For the groups with the pressure dependent shape in the residuals, tcor was held at some value lower than the fit originally came up with. Usually tcor was adjusted by -0.002 and the group refit. The resulting residuals between 2000 to 5000 dbars would be centered around 0 with a spread reduced from +/-0.1 to +/-0.04 but the shape would remain in the upper 2000 dbars. Special notes for fitting oxygen data for particular stations: The oxygen temperature (OT) coefficients were changed for the post processing. There were several instances of the CTD profile not reaching the oxygen minimum, or overshooting the minimum. This may have been due to not having the proper OT coefficients in the at-sea station header files. These were corrected during post-processing so all calibration files now have the proper OT coefficients for each CTD. OT coefficient changes: Station applied to Change made ------------------ ------------------------------------------ 857, 870-892 replaced wrong 38 bias with right 38 bias. 859-862 replaced 38 OT cal with 44 OT cal. 865-869 left as is. 893-979, 899, 978 replaced 38 OT wrong bias with 44 OT cal. 979 replaced wrong 38 bias with right 38 bias. 980 replaced wrong 38 bias with right 38 bias. 981-004 replaced wrong 38 bias with right 38 bias. 005-014 replaced wrong 38 bias with right 38 bias. Stations 859 to 862 were taken with ICTD 1344 but used ICTD1338's oxygen assembly. 1344's OT calibration terms were put into the cal file. Stations 877, 878, 879 and 004 were scaled using the at-sea OT and oxygen current (OC) terms. With the new OT terms, it was not possible to get as good a fit as the at-sea results. The terms arrived at had unrealistic numbers such as a negative lag but was used anyway for the resulting good fit. Stations 857 and 858, test stations, had the oxygen quality word flagged '4' (bad) in the downtrace. All the bottles were deep and not useful for finding a fit for the whole profile. Station 859, the next station in the same locations as 857 and 858, had bottles except for the top 800dbar due to a pylon failure. Even with a better fit this top should be labeled '3' (questionable). Station 860, a test station for water sampling. The downtrace oxygen was labeled '4' due to all bottles fired deep. Stations 906 to 904 have clear shape in the bottom water that may or may not be real. The uptrace looks as if it follows the shapes loosely, not really until the larger features around 2000dbar does it really follow the downtrace. Station 937 had extra bottles taken deep to watch the +/- 0.05ml/l variation in oxygen. The bottles do look like they agree with the oxygen. Station 987, a -0.04 ml/l shift in oxygen at 2711dbar does not look real, and does not agree with bottle or following stations. It has been flagged '3' (questionable). TABLE 2: OXYGEN FITTING COEFFICIENTS FOR STATIONS WITH NORMAL ALGO-RITHM Below is a list of the coefficients used to scale the oxygen data for all but 53 stations that have a special fitting routine applied (noted as "special fit"). stn bias slope pcor tcor wt lag --- ------ ---------- ---------- ------- ---- ---- 857 -0.011 0.2915E-03 0.6243E-03 0.0156 0.60 3.00 858 -0.023 0.1192E-02 0.1798E-03 -0.0300 0.80 1.00 859 -0.023 0.1192E-02 0.1798E-03 -0.0300 0.80 1.00 860 - 862 special fit. 863 0.004 0.1296E-02 0.1407E-03 -0.0524 0.60 0.30 864 -1.375 0.1136E-03 0.2034E-03 -0.0522 0.60 1.00 865 - 869 special fit. 870 0.006 0.3862E-03 0.6243E-03 0.0156 0.60 3.00 871 0.009 0.6467E-03 0.3590E-03 0.0064 0.60 3.00 872 0.009 0.6467E-03 0.3590E-03 0.0064 0.60 3.00 873 0.039 0.8729E-03 0.1179E-03 -0.0155 0.60 3.00 874 0.039 0.8729E-03 0.1179E-03 -0.0155 0.60 3.00 875 0.022 0.1472E-02 -0.1200E-03 -0.0397 0.60 3.00 876 0.022 0.1472E-02 -0.1200E-03 -0.0397 0.60 3.00 877 0.004 0.1318E-02 -0.4643E-05 -0.0341 0.10 4.00 878 -0.018 0.4243E-02 -0.2527E-03 -0.0677 1.32 -0.3 879 -0.018 0.4243E-02 -0.2527E-03 -0.0677 1.32 -0.3 880-892 special fit. 893 0.005 0.1170E-02 0.1499E-03 -0.0272 0.80 1.00 894 0.022 0.1141E-02 0.1508E-03 -0.0271 0.80 1.00 895 0.009 0.1273E-02 0.1416E-03 -0.0298 0.80 1.00 896 0.017 0.1281E-02 0.1444E-03 -0.0275 0.80 1.00 897 0.017 0.1281E-02 0.1444E-03 -0.0275 0.80 1.00 898 0.019 0.1316E-02 0.1398E-03 -0.0275 0.80 1.00 899 -1.427 0.1162E-03 0.1901E-03 -0.0283 0.60 1.00 900 0.017 0.1281E-02 0.1444E-03 -0.0275 0.80 1.00 901 0.011 0.1376E-02 0.1469E-03 -0.0294 0.80 1.23 902 0.011 0.1376E-02 0.1469E-03 -0.0294 0.80 1.23 903 0.011 0.1376E-02 0.1469E-03 -0.0294 0.80 1.23 904 0.011 0.1376E-02 0.1469E-03 -0.0294 0.80 1.23 905 0.011 0.1376E-02 0.1469E-03 -0.0294 0.80 1.23 906 0.011 0.1376E-02 0.1469E-03 -0.0294 0.80 1.23 907 0.011 0.1376E-02 0.1469E-03 -0.0294 0.80 1.23 908 0.011 0.1376E-02 0.1469E-03 -0.0294 0.80 1.23 909 0.011 0.1376E-02 0.1469E-03 -0.0294 0.80 1.23 910 0.036 0.1149E-02 0.1427E-03 -0.0270 0.80 1.00 911 0.003 0.1214E-02 0.1503E-03 -0.0280 0.80 1.00 912 - 922 special fit. stn bias slope pcor tcor wt lag --- ------ ---------- ---------- ------- ---- ---- 923 -0.006 0.1045E-02 0.1665E-03 -0.0243 0.74 9.34 924 -0.006 0.1045E-02 0.1665E-03 -0.0243 0.74 9.34 925 0.000 0.1080E-02 0.1463E-03 -0.0240 0.80 1.00 926 0.000 0.1080E-02 0.1463E-03 -0.0240 0.80 1.00 927 0.000 0.1080E-02 0.1463E-03 -0.0240 0.80 1.00 928 0.000 0.1080E-02 0.1463E-03 -0.0240 0.80 1.00 929 0.000 0.1080E-02 0.1463E-03 -0.0240 0.80 1.00 930 - 933 special fit. 934 -0.014 0.1582E-02 0.1336E-03 -0.0297 0.80 1.00 935 -0.024 0.1664E-02 0.1146E-03 -0.0304 0.80 1.00 936 -0.024 0.1664E-02 0.1146E-03 -0.0304 0.80 1.00 937 -0.020 0.1612E-02 0.1419E-03 -0.0300 0.80 1.00 938 -0.020 0.1612E-02 0.1419E-03 -0.0300 0.80 1.00 939 -0.020 0.1612E-02 0.1419E-03 -0.0300 0.80 1.00 940 -0.020 0.1612E-02 0.1419E-03 -0.0300 0.80 1.00 941 -0.020 0.1612E-02 0.1419E-03 -0.0300 0.80 1.00 942 -0.020 0.1612E-02 0.1419E-03 -0.0300 0.80 1.00 943 -0.020 0.1612E-02 0.1419E-03 -0.0300 0.80 1.00 944 -0.020 0.1612E-02 0.1419E-03 -0.0300 0.80 1.00 945 -0.020 0.1612E-02 0.1419E-03 -0.0300 0.80 1.00 946 -0.020 0.1612E-02 0.1419E-03 -0.0300 0.80 1.00 947 -0.006 0.1296E-02 0.2061E-03 -0.0236 0.80 1.00 948 -0.005 0.1300E-02 0.2061E-03 -0.0236 0.80 1.00 949 -0.005 0.1300E-02 0.2061E-03 -0.0236 0.80 1.00 950 0.007 0.9440E-03 0.3342E-03 -0.0105 0.80 1.00 951 -0.011 0.1433E-02 0.1654E-03 -0.0278 0.80 1.00 952 -0.011 0.1433E-02 0.1654E-03 -0.0278 0.80 1.00 953 -0.011 0.1433E-02 0.1654E-03 -0.0278 0.80 1.00 954 -0.011 0.1433E-02 0.1654E-03 -0.0278 0.80 1.00 955 -0.011 0.1433E-02 0.1654E-03 -0.0278 0.80 1.00 956 -0.011 0.1433E-02 0.1654E-03 -0.0278 0.80 1.00 957 -0.154 0.1608E-02 0.5058E-03 -0.0163 0.70 1.00 958 -0.014 0.1477E-02 0.1318E-03 -0.0289 0.80 1.00 959 -0.014 0.1477E-02 0.1318E-03 -0.0289 0.80 1.00 960 -0.014 0.1477E-02 0.1318E-03 -0.0289 0.80 1.00 961 -0.014 0.1477E-02 0.1318E-03 -0.0289 0.80 1.00 962 -0.019 0.1310E-02 0.1542E-03 -0.0240 0.80 1.00 963 - 969 special fit. stn bias slope pcor tcor wt lag --- ------ ----------- ---------- ------- ---- ---- 970 0.131 0.13908E-02 -0.9363E-03 -0.0277 0.80 1.00 971 - 979 special fit. 980 0.005 0.3081E-03 0.1529E-03 -0.0294 0.60 3.00 981 0.011 0.2968E-03 0.1529E-03 -0.0294 0.60 3.00 982 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 983 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 984 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 985 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 986 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 987 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 988 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 989 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 990 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 991 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 992 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 993 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 994 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 995 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 996 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 997 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 998 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 999 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 000 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 001 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 002 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 003 0.001 0.3028E-03 0.1569E-03 -0.0258 0.60 3.00 004 0.0082 0.3217E-03 0.1485E-03 -0.0277 0.90 1.00 005 0.009 0.2903E-03 0.1476E-03 -0.0265 0.71 3.00 006 0.009 0.2903E-03 0.1476E-03 -0.0265 0.71 3.00 007 0.018 0.2455E-03 0.2161E-03 -0.0205 0.60 3.00 008 0.009 0.2903E-03 0.1476E-03 -0.0265 0.71 3.00 009 0.009 0.2903E-03 0.1476E-03 -0.0265 0.71 3.00 010 0.009 0.2903E-03 0.1476E-03 -0.0265 0.71 3.00 011 0.009 0.2903E-03 0.1476E-03 -0.0265 0.71 3.00 012 0.009 0.2903E-03 0.1476E-03 -0.0265 0.71 3.00 013 0.009 0.2903E-03 0.1476E-03 -0.0265 0.71 3.00 014 0.009 0.2903E-03 0.1476E-03 -0.0265 0.71 3.00 "Special fit" indicates that a revised oxygen fitting algorithm was used for these stations. See next section for details. SPECIAL OXYGEN ALGORITHM FITTING Fifty-three stations had the problem of fitting the CTD oxygen profile to the bottle data. Bob Millard revised the oxygen algorithm in an attempt to improve the oxygen data from ICTD stations with pressure dependent oxygen residuals using the original Owens & Millard oxygen algorithm: oc = (ocr+lag*docr/dt)*slope+bias Two changes to the oxygen algorithm of Owens & Millard (1985) result in the equation below: ox = oc*oxsat* exp(tcor*(T+wt*(OT-T)+pcor*P) First is the uncoupling of the temperature parameters in the exponential of the algorithm (tcor*wt). This becomes particularly helpful if the oxygen temperature (OT) term does not have a valid calibration. A new term involving the cross-term between pressure and temperature has been added to the algorithm as it picks up additional variance. Note that the oxygen lag term is negative for a number of station groups listed in table 3 below. In recognition of the inadequate performance of the oxygen sensor modules used for these stations, we opted for the best fit to the water sample oxygen data even though the terms may not be physically realistic. ox = oc*oxsat* exp(tcor1*T+tcor2*OT+pcor*P+ptcor*P*T) The following figures demonstrate how well the adjusted algorithm has done in fitting two station groups that could not be fit with the original algorithm. Figure 5: Oxygen fitting with new algorithm: Stations 865 to 869: Original fit shows distinct pressure dependent shape as opposed to fit with new algorithm. (Above plots display differences of bottle to CTD oxygen ml/l by pressure in decibars.) Figure 6: Oxygen fitting with new algorithm: Stations 912 to 922: Fit with new algorithm removes pressure dependent shape of residuals. (Above plots display differences of bottle to CTD oxygen ml/l by pressure in decibars.) Figure 7: Refit of station group 912 to 922 (notice that shallow station 918 rosette data are bad). Figure 8: Refit of stations 930 to 933 in comparison to surrounding stations. Table 3: OXYGEN DATA FITTING COEFFICIENTS FOR REVISED ALGORITHM The following is a table of coefficients used to scale the oxygen data in the 53 stations that exhibited oxygen fitting problems. Note that some of the terms (i.e. lag) are unrealistic; they do, however, allow these data to be fit to the rosette water sample values. These are the data that could not be fit with the standard oxygen algorithm. stn bias slope pcor tcor1 tcor2 lag ptcor --- --------- -------- -------- --------- --------- ------ ----------- 860 -0.007971 0.001741 0.000156 -0.118095 0.050579 -4.17 -0.00006604 861 -0.007971 0.001741 0.000156 -0.118095 0.050579 -4.17 -0.00006604 862 -0.007971 0.001741 0.000156 -0.118095 0.050579 -4.17 -0.00006604 865 0.016388 0.001236 0.000163 -0.027216 -0.007340 -0.82 -0.00003362 866 0.016388 0.001236 0.000163 -0.027216 -0.007340 -0.82 -0.00003362 867 0.016388 0.001236 0.000163 -0.027216 -0.007340 -0.82 -0.00003362 868 0.016388 0.001236 0.000163 -0.027216 -0.007340 -0.82 -0.00003362 869 0.016388 0.001236 0.000163 -0.027216 -0.007340 -0.82 -0.00003362 880 0.157432 0.000496 0.000439 0.077879 -0.080973 -3.74 -0.00011072 881 0.052984 0.000207 0.001009 0.073267 -0.044510 -11.85 -0.00010797 882 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 883 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 884 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 885 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 886 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 887 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 888 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 889 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 890 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 891 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 892 0.046955 0.001134 0.000207 -0.011526 -0.015070 0.03 -0.00004038 912 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 913 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 914 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 915 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 916 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 917 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 918 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 919 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 920 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 921 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 922 0.018098 0.001265 0.000161 -0.011542 -0.016859 -0.84 -0.00002167 930 -0.028873 0.001555 0.000177 -0.016931 -0.010603 -5.01 -0.00003549 931 -0.028873 0.001555 0.000177 -0.016931 -0.010603 -5.01 -0.00003549 932 -0.028873 0.001555 0.000177 -0.016931 -0.010603 -5.01 -0.00003549 933 -0.028873 0.001555 0.000177 -0.016931 -0.010603 -5.01 -0.00003549 963 -0.013299 0.001418 0.000157 -0.009204 -0.015968 1.10 -0.00002067 964 -0.013299 0.001418 0.000157 -0.009204 -0.015968 1.10 -0.00002067 965 -0.013299 0.001418 0.000157 -0.009204 -0.015968 1.10 -0.00002067 966 -0.013299 0.001418 0.000157 -0.009204 -0.015968 1.10 -0.00002067 967 -0.013299 0.001418 0.000157 -0.009204 -0.015968 1.10 -0.00002067 968 -0.013299 0.001418 0.000157 -0.009204 -0.015968 1.10 -0.00002067 969 -0.013299 0.001418 0.000157 -0.009204 -0.015968 1.10 -0.00002067 971 -0.019304 0.001652 0.000148 -0.011510 -0.019372 1.83 -0.00004173 972 -0.019304 0.001652 0.000148 -0.011510 -0.019372 1.83 -0.00004173 973 -0.019304 0.001652 0.000148 -0.011510 -0.019372 1.83 -0.00004173 974 -0.019304 0.001652 0.000148 -0.011510 -0.019372 1.83 -0.00004173 975 -0.019304 0.001652 0.000148 -0.011510 -0.019372 1.83 -0.00004173 976 -0.019304 0.001652 0.000148 -0.011510 -0.019372 1.83 -0.00004173 977 -0.019304 0.001652 0.000148 -0.011510 -0.019372 1.83 -0.00004173 978 0.411273 0.000324 0.000045 0.266932 -0.283316 102.98 -0.00008445 979 -0.035108 0.001632 0.000151 -0.018120 -0.012538 -2.50 -0.00003505 The quality of the final oxygen data is documented by the residual plots below: Figure 9: Leg 1: Differences between final calibrated down oxygen data and rosette water sample data. Figure 10: Leg 2: Differences between calibrated down oxygen data and rosette water sample data Figure 11: Stations 978 and 979 demonstrate that there were times during the cruise when the CTD was opened up and the oxygen current digitizer changed, resulting in a scaling change. The following notes document instances where the quality word flag of the CTD oxygen in the CTD downtrace files was changed to 4 to signify bad data. Stations 920-922, 915, 918: Set flag of 1st oxygen value to 4 because oxygen current value is low by 0.8 ml/l. Station 858: Oxygen bad between 237 to 241 and 275 dbars; set quality word =4. Station 978: From the surface to 71 dbars the CTD oxygen is flagged bad. Figure 12: Station 978 oxygen data unsalvageable above 71 dbar. DATA PROCESSING DETAIL NOTES: STATION 863: Made the internally recording (IR) backup CTD, CTD 1338, the primary data for the station instead of CTD 9. CTD9's oxygen and salinity in the down profile were bad due to noisy pressure requiring heavy interpolation. ICTD 1338 data were used to make the down 2-dbar file. CTD 9's info was left with the bottle file. There were problems making the bottle file from the IR CTD. Note, there are different up and down cals, one for CTD1338, the other for CTD9. STATION 909: ICTD1344 jumped in salinity by -0.002psu at 3453dbar. Profile continued down at this lower salinity until reaching the bottom when it jumped back +0.001psu. The uptrace bottles and surrounding stations did not support this feature. The salinity below 3453 was replaced with the uptrace salinity. STATIONS 973 to 979: ICTD 1344 conductivity sensor was jumping low, away from the profile and then back to the real value over these set of stations. The problem appeared to be a loose mounting on the conductivity sensor that was epoxied into place after station 981. STATION 973: Replaced the bad downtrace salinity with uptrace salinity over the pressure ranges 1191 to 1641 dbar and 1707 to 2747 dbar. STATION 974: Replaced the bad downtrace salinity with uptrace salinity over the pressure range 1921 to 3773 dbar (bottom). STATION 975: Large interpolations over bad sections. The ranges are listed in the interpolation file: Station, Start pressure, 3=salinity, Ending pressure 975,939,3,1127 975,1447,3,1453 975,1455,3,1457 975,1479,3,1485 975,1781,3,1833 975,2083,3,2157 STATION 976: Interpolate over the bad section. The range is listed in the interpolation file: Station, Start pressure, 3=salinity, Ending pressure 976,2191,3,2251 STATION 977: Leave as is, there is some odd shape in the 900 to 1100 dbar range but it is loosely mimicked by the uptrace. STATION 979: Interpolate over bad section. The range is 2683 to 3151 dbar. There is some shape in the 800 to 1200 dbar section but again, it is loosely copied by the uptrace data. STATION 978, 980 to 014: ICTD1338 downtrace salinity was fit to bottles for downtrace scaling term. Uptrace left as it was. There are two cal files for each station, one for uptrace data *.CU8 and one for downtrace data *.C08. The *.CTD files of 2 dbar pressure averaged and centered downtrace profiles and the *.SEA bottle file both refer to stations 1000 to 1014 as 0 to 14. The *.SEA files (one for leg1 and one for leg2) have been updated with new CTD pressure, temperature, potential temperature, salinity and oxygen data produced from the latest set of calibration coefficients. Final nutrient data has been merged into the *.SEA files as well. A distinct processing sequence of events occurred after rescaling oxygen data for the 53 "problem oxygen " stations. The following was done using Matlab: 1. The WOCE format files submitted in July 1998 were the starting point. 2. For those stations requiring revised CTD oxygen data, the new oxygen data were overwritten into the original files. 3. The original CTD oxygen data in the SEA file were also overwritten with the newest oxygen data. The bottle file pressures were used to merge the 2 dbar down-profile CTD oxygen data from the stations reprocessed into the bottle file. The SEA file was also put through an initial pass at setting quality flags for both CTD salt and oxygen: The quality word of both the CTD oxygen and CTD salinity were compared to the bottle values using a screening criteria that varied with pressure. Within the following pressure levels, differences abs(Oxw-Oxcw) exceeding the value given are marked questionable. Pressure less than 500 dbars Dox > 0.5 ml/l. Pressure between 500 and 1500 dbars Dox > 0.2 ml/l. Pressure greater than 1500 dbars and Dox > 0.1 ml/l. All CTD oxygen values equal to -9.0 have had their quality word set equal to 9. The original bottle file I1A.SEA had newly calibrated down CTD oxygen data merged into it and CTD salinity and oxygen data quality control edited. The resultant file is I1AA.SEA. The original bottle file I1B.SEA was output to file I1BB.SEA. The file I1B.SEA had a second set of four header records that were found to be inserted between station 999 and 0 (ie, station 1000). These headers were removed from file I1aa.SEA. RESOLVED DATA ISSUES: Concern over possible pressure hysteresis in ICTD 1338 found to be caused by internal wave signal. Issue was looked at by Bob Millard and determined not to be instrumen- tal hysteresis but the signal of vertical heaving by internal waves. Non-compliant IOS standard water, batch P-124 from box 2. Standard water believed to be .002 fresh. Problem recognized immediately, only two stations resulted in questionable water sample salts from using this batch of standard water. Spikes and jumps in all data fields throughout the cruise caused extensive editing. The entire dataset has been edited and spikes, jumps, etc have been removed. Pre- to post-cruise laboratory temperature calibrations of CTD 1344 and CTD 1338 showed changes. A combined pre and post cruise temperature calibration has been selected for the ICTDs as described in the calibration summary section. Oxygen fitting problems due to oxygen sensor failures and change-outs. Several factors slowed the CTD oxygen fitting. Poor quality oxygen sensors necessitated frequent changes of sensors: 7 changes total. This resulted in at least as frequent changes in oxygen calibration coefficients. Swapped oxygen assemblies for stations 859 to 862 altered the oxygen temperature calibrations, another complication to the data fitting. Concentrations at the oxygen minimum come close to zero for 35 stations. It took substantially more time than usual to find a calibration that resulted in CTD oxygen data consistent with the water sample data but without going negative. As noted in the oxygen calibration section, a revision to the Owens- Millard algorithm was tried and found to provide an acceptable fit for the oxygen data for 53 stations that were previously not able to be fit with the original algorithm. CTD equipment failures caused extra processing to fit data to water samples and improve data. Stations that had trouble with the primary instrument took extra time to correct. Such trouble includes segments of unreadable data or individual sensors not responding. Because two CTDs were usually on the frame, along with a second, independent temperature sensor, these problem stations were recovered by using data from the other instrumentation. For example, in the case of station 973, data from both primary and backup was used to construct the final hydrographic profile. REFERENCE: Owens, W. B. and R. C. Millard Jr. (1985). A new algorithm for CTD oxygen calibration. Journal of Physical Oceanography, 15, 621-631. ATSEA.DOC NOTES ON WORK DONE TO PARTICULAR STATIONS: EXTRACTS FROM AT-SEA WATCH- STANDERS' LOG HIGHLIGHTING DATA PROBLEMS AND FIXES. Station 858: CTD 9 Pressure dropout and cast aborted- no water samples. CTD9 subsequently found to have failed pressure sensor, apparently due to corrosion in sensing element. CTD cannot be fixed at sea. Station 859: ICTD1344. Pylon failure, at bottle 18 pylon homed itself with message error was 242. Problem due to interfering telemetry of CTD and pylon. AFTER Station 862: ICTD1338 ICTD1338 opened to switch from FSK to memory mode, and will be used as second CTD on frame. Station 863: CTD9 with ICTD1338 in Memory mode. After Test station for CTD9, CTD 9 opened and found dessicant packs to be caught btw boards, causing components on board to short out. Thought was fixed, but everything dropped out twice during this station. -USE ICTD1338 DATA FOR THIS STATION Station 864:CTD12, Test station for CTD12, after shipping got complete garbage trying to run through seacable at 180 ma, switched to running at 250 ma seemed to run fine on deck, so tried a test station. -down trace- cond jumps -uptrace- large TMR error that was counted as btl tags scan # 47614, 1297 dbar 55 btl tags 11-37 taken out, and 12 Station 865: ICTD1344 with new oxygen sensor 5-06-03. CHANGED TO MKIII DECK UNIT ON UP CAST -a lot of noise in cast, changed over deck unit to MarkIII from FSI DT- 1050, seemed to cleanup data. Station 867:ICTD1344 loss of signal during down cast, fsk was still there but pressure pegged out at 6552. Put power supply in standby and switched to DT1050, no response. Put power supply back in standby, swapped back to MKIII DU and voila data returned. CAST ABORTED Down trace- weird pressure jump in beginning of cast complete pressure dropout at scans 26466-29569, 647 dbar Station 869:ICTD1344 on down trace pressure pegged at 6552, FSK ok. Tried powering down for 5 min then back up- no luck, package brought back to 400m powered down then back up- no luck. Brought package to 200m powered down then backup - no luck, Tried firing 3 btl- no effect. CAST ABORTED- BROUGHT BACK TO SURFACE downcast- complete pressure drop out at 27832 used this as cut off scan number in header. After station 869: ICTD1338 OPENED TO CHANGE TO FSK MODE After station 870: I ICTD1344 opened up, found un-insulated wires, sloppy wiring. Problems repaired. ICTD1344 memory card now installed. SALINOMETER 10 BLEW POWER SUPPLY, CHANGED OUT OK After station 872: ICTD1338, ICTD1344 memory. ICTD1344 SURGERY, ICTD OPENED. Power board replaced with spare. Station 875:ICTD1338 fter finished station tried to send pylon home, received comm errors, pylon draws .280 A, pylon trying to move to home, but seemed stuck, helped move and washed out, pylon them seemed to be ok, drew .1 A. Station 884:ICTD1338 -down trace PRESSURE JUMP pressure jumped from 5.9 to 7.7 and did not jump back. scan # 14458 interped btw 5.9 dbar. -uptrace- cast started on deck and not erased fast temperature jump Station 886:ICTD1338 -Pylon problems- computer return after firing 1 01 7 2 02 7 tried to position to 3- comm error reinitialized and positioned to 2 success -CTD powered up at 0725 After station 888: ******ICTD1344 OPENED ****** ICTD not used since last opening to replace power board. After station 892: ******ICTD1344 AND ICTD1338 BOTH OPENED TO SWAP OUTMEMORY CARD********* Station 900:ICTD1344, P1484, SIOSCI, MKIII DU, FRAME B ICTD 1338 INTERNALLY RECORDING Cast one aborted, sensor covers left on package CTD harness replaced and connectors re-greased, still a problem- a lot of synch errors from CTD Problem found to be in termination, swapped to port sea cable problem still continued. Turned off pylon power and synch error went away. Station 907:ICTD1344 MODEM CARD ON SIOSCI MODIFIED TO REDUCE TRANSMIT LEVEL, HOPING TO AVOID SYNCH ERRORS- lower surf xmit Station 910:ICTD1344 NEW OXYGEN SENSOR 5-06-02 Station 913:BACKUP ICTD1338 ON FRAME, BUT NOT RECORDING IN MEM MODE- bat died Station 915:BACKUP ICTD1338 INTERNALLY RECORDING- new battery -down trace-clean Station 923:ICTD1344 NEW OXYGEN SENSOR (5-07-02) FAWL CONNECTOR ON IRICTD1338 FAILED, ICTD1338 WAS REMOVED AND A 3 PIN BULKHEAD CONNECTOR WAS PUT IN PLACE. Station 925:ICTD1344 ICTD1338 INTERNALLY RECORDING, POWERED DOWN SEACABLE PORT SEACABLE lots o' synch errors, pylon turned off during down trace winch stopped at 4350 dbar to check level wind of winch pylon problems trying to fire bottle 35, tried turning off and on pylon, reinitializing it, kept saying 02 7. When brought on deck found pylon to be at position 7. Reinitialized on deck and seemed to work fine. -down trace- very noisy in conductivity, fast temp, oxtemp jumps pressure -150 jumps synch errors- 55 errors -uptrace- cleaned up only around btl tags took out btl tag 33. Station 903:ICTD1344 NEW OXYGEN SENSOR 4-10-2 After station 942: *******CONDUCTIVITY SENSOR ON BOTH ICTD1338 AND 1344 WERE CLEANED***** Station 948:ICTD1344 pylon problems in beginning of cast, reinitialized, retried re-initialized and retried again, worked on third attempt. After station 955: *****PROBLEMS WITH INTERNALLY RECORDING ICTD1338********* Station 958:ICTD1344 BOTTOM CONTACT WITH PACKAGE pylon problems, comm errors with pylon, however all bottles were fired After station 961: ************ICTD1338 UPDATED EEPROM VERSION 1.9SMF ********* ***********CHANGED OUT POWER SUPPLY AND PUT A NEW ONE IN********* Station 973:ICTD1344 PRIOR TO STATION TOOK OUT MECCA WYE, AND 2 PIN CONNECTOR TO MECCA, CHANGED OUT THE HARNESS ****IN FINAL DATA USE ICTD1344 OXYGEN TRACE w/ ICTD1338 CONDUCTIVITY TRACE*** STATION 973 *.prs file currently has oxygens from iCTD1344 and salts from IRICTD1338. M-file s973sal.m can be used to replace the the salt column from kj45d973.prs. Station 975:ICTD1344 PRIOR TO STATION, SWAPPED FSKICTD CONDUCTOR TO MEM ICTD CONDUCTOR Station 977:ICTD1344 CLEANED CONDUCTIVITY SENSOR ON ICTD1344, CHECKED FOR ROTATION Station 978: ICTD1344 *****IN FINAL DATA SET USE IRICTD1338 DATA, THIS WAS DONE OCT95**** **** ICTD1344 DATA BACKED UP ONTO POSTPROC DISKS AS WELL AS **** **** ICTD1338 DATA **** Station 980: ICTD1344, ICTD1338 in Memory mode. New oxgen sensor on ICTD1344 #4-12-04 ICTD1338 IN MEMORY w/ OTM 1372, POWER DOWN SEA CABLE. For final dataset use ICTD1338 data - note this was done in Oct95. ICTD1338 data backed up in POSTPR data, ICTD1344 only backed up raw data. Water sample salts flagged as 3, appear to be .002 fresh, problem with standard water. Station 981: ICTD1338 Water sample salts flagged as 3, appear to be 0.002 fresh, problem with standard water was subsequently found to be cause. After station 981: ICTD1344 ICTD1344 FIRMWARE UPGRADED to version 1.9SMF providing 14 bits of oxygen digitization. CONDUCTIVITY SENSOR STEM EPOXIED IN PLACE SO IT WILL NOT ROTATE. OTM CHANGED TO VARIABLE 16, AND REDUNDANT TEMP TO VARIABLE 17, TO MATCH PAST CRUISES. Station 991: ICTD1344 IN MEMORY w/ OTM 1372- new oxygen sensor (5-06-01) Station 1005:ICTD1338 *****RECORD LAYOUT CHANGED TO INCLUDE PRSTEMP VAR#14**** Stopped cast at 1000m on down cast to see how pressure temp reacts, also stopped at approx 2750m. Station 1012:ICTD1338, Fast thermistor stem is not tight, tech did not repair anything; damage might result. = end of Watchstander's log = CRUISE INTERPOLATION DOCUMENTATION List of interpolations applied after the pressure averaging and centering. The columns are for station number, the starting bad pressure, the column to be interpolated over (3=salinity, 4=oxygen), and the ending bad pressure. This does not list the edits done to the raw data using the EG&G software's ctdpost editor. SALINITY INTERPOLATIONS 002 1291 3 1297 002 1353 3 1367 002 1405 3 1413 005 2773 3 2779 005 1001 3 1015 005 881 3 885 864 2407 3 2413 872 9 3 9 964 1995 3 1999 964 2243 3 2255 964 1127 3 1137 964 1429 3 1435 975 939 3 1127 975 1447 3 1453 975 1455 3 1457 975 1479 3 1485 975 1781 3 1833 975 2083 3 2157 976 2191 3 2251 979 2683 3 3151 986 1535 3 1545 987 671 3 697 987 1043 3 1051 987 1395 3 1399 988 1321 3 1328 988 1419 3 1423 990 1187 5 1195 991 1241 3 1245 995 937 3 947 997 1755 3 1771 999 921 3 931 999 1063 3 1081 OXYGEN INTERPOLATIONS 984 2321 4 2341 984 2559 4 2575 984 2871 4 2885 984 2981 4 2991 984 3087 4 3091 987 2717 4 2725 988 2125 4 2131 988 3357 4 3361 989 2977 4 2983 990 3353 4 3357 POST CRUISE PROCESSING DOCUMENTATION (July 1998) SUMMARY OF STATIONS CTD 1338 857,863,870-892,978,980,981-1014 CTD 1344 859-862,865-869, 893-898,900-978 CTD 9 858 CTD 12 864,899 There are no bottle files for stations 858,867 and 869 due to the pressure signal having dropped out requiring the cast to be aborted. Station 859 had bottles up to 800db until a jellyfish got caught up in the pylon causing the pylon to home itself. PRE V POST CALIBRATIONS PRESSURE ICTD 1338 changed by 1.5 db, chose to use an average of the pre and post cruise cal. TEMPERATURE The ICTD 1344 temperature calibration changed pre to post cruise laboratory calibration with a bias shift of +.002 deg C. CTD reading warmer at the post cruise cal than at the pre cruise cal. The point at where the temperarture shift occured was looked for but not found. The most reliable search was to look at same station primary and internal recording CTDs. They did not show where the jump occured. The fast thermister's were also compared and points where the salinity cal changed. There was not enough proof to point to a spot where the jump occured so instead an average of the pre and post cruise calibrations was used to process the data. ICTD 1338 had a small change, less than .002 deg C. The pre and post temperature cal were averaged to be used with the post cruise processing. SALT Plot results of deep water revealed that there was a CTD dependent bias: 1338: *.PRS CTD salt read too high ~.002psu or temperature was too low compared to *,SEA file. 1344: *.PRS CTD salt read too low ~.001 psu or temperature was too high compared to *.SEA file. The consistancy of the bias between stations indicates it was probably not a real ocean measurement such as measuring internal waves, but some kind of instrument, package dynamic or bottle artifact. All ICTDS 1338 stations have a sig. bias, with the downtrace always saltier than the bottles. The uptrace has been fit well, but the uptrace is fresher than the downtrace. To correct for the difference, the downtrace salinity, the group of station 978 to 1014, was fit to the bottle data. The results looked good. The earlier group of 1338 stations seemed to fit well after forcing the bottom bottles to be met by the CTD so were not refit using the downtrace. ICTD 1344 downtrace trends toward being fresher than the bottles. The uptrace and downtrce agree, but the fits were not working well. Rework some of the fits, concentrating on matching up the CTD and salts in the bottom water. CTD comparisions were made with the primary and backup data from the same stations. Pressure agreed very well, bottom depths were within 1db on the stations checked. Temperature would stray, +/-.002 at the bottom, sometimes ictd 1338 being warmer, sometimes ictd 1344. probably a factor of where they were located on the frame. Stations 936-938,940-941 A Pressure dependant shape could not be removed without changing beta (and alpha) conductivity terms. After station 942, the conductivity cell was cleaned although no specific reason is given. The difficult calibrations from station 936 to 942 could have been induced by fouling or buildup on the conductivty cell. Stations 936, 937 and 938 have BETA changed from 1.5e-8 to .75e-8 Stations 940 and 941 have BETA changed from 1.5e-8 to .75e-8 and ALPHA changed from -6.5e-6 to -9.75e-6. Station 923 and 954 both have salt changes that looked questionable until the uptrace was overlaid and followed the shape of the downtrace. Station 923 freshens around 2 deg C. Station 954 has spikes and a shift at 1750db, 1900db and 2250 db that are clearly repeated in the uptrace. OXY The oxygen temperture (OT) coefficients were changed for the post processing. Found that there were several instances of the CTD profile not reaching the oxygen minimum, or overshooting the minimum. This may have been due to not having the proper OT coefficients so decided to remake calibrations files that have the proper pre cruise OT coefficients for each CTD. OT coefficient changes: Sta, Apply to, Change made ---- ---------------- ------------------------------------------ 857 857,870-892 replaced wrong 38 bias with right 38 bias. 859 859-862 replaced 38 OT cal with 44 OT cal. 865 865-869 left as is. 893 893-979 x899,978 replaced 38 OT +wrong bias with 44 OT cal. 978 978 replaced wrong 38 bias with right 38 bias. 980 980 replaced wrong 38 bias with right 38 bias. 981 981-004 replaced wrong 38 bias with right 38 bias. 005 005-014 replaced wrong 38 bias with right 38 bias. Stations 859 to 862 were taken with ICTD 1344 but used ICTD1338's oxygen assembly. 44's ot term were put into the cal file. FITTING Some stations fit just fine and others had a definate pressure dependant shape in the residuals. It was a similar shape that reoccured in different groups. The shape was more pronounced in some groups than others. A weight of .8 and lag of 1 was consistant from a few of the larger groups. Most of the groups had this weight and lag held during the fits since many groups came up with weights over 1 and lags below 0 when allowed to fit for those parameters. For the groups with the pressure dependant shape in the residuals, tcor was held at some value lower than the fit originally came up with. Usually tcor was adjusted -.002 and the group refit. The resulting residuals between 2000 to 5000 db would be centered around 0 with a spread reduced from +/-.1 to +/-.04 but the shape would remain in the upper 2000 db. Groups with the pressure dependant shape: 859-862 865-869 911-922 930-933 934 935 937-946 962-969 971-979 Stations 877,878,879 and 004 were scaled using the atsea ot and oc terms. With the new OT, it was not possible to get as good a fit as the atsea results. The terms arrived at had unrealistic numbers such as a negative lag but was used anyway for the resulting good fit. 50 stations had the problem of fitting to the top water or fitting to the bottom but not both at once. Bob Millard agreed to try his method of coming up with two fits for a single station and then blend them together at the middle. The stations have '4's (bad) in the quality word of the CTD files. The stations are: 859,861-862 865-869 880-881 882-892 912-922 933 963-969 971-977 978-979 Stations 857-858, test stations, had the oxygen quality word flagged '4' (bad) in the downtrace. All the bottles were deep and not useful for finding a fit for the whole profile. Station 859, the next station in the same locations as 857 and 858, had bottles except for the top 800db due to a pylon failure. Even with a better fit this top should be labeled '3' (questionable). Station 860, a test station for water sampling. The downtrace oxygen was labeled '4' due to all bottles fired deep. Stations 906 to 904 have clear shape in the bottom water that may or may not be real. The uptrace looks as if it follows the shapes loosely, not really until the larger features aroud 2000db does it really follow the downtrace. Station 937 had extra bottles taken deep to watch the +/- .05ml/l variation in oxygen. The bottles do look like they agree with the oxygen. Station 987, a -.04 ml/l shift in oxygen at 2711db does not look real, and does not agree with bottle or following stations. It has been flagged '3' (questionable). NOTES ON WORK DONE TO PARTICULAR STATION: STATION 863 Made the internally recording (IR) backup CTD, CTD 1338, the primary data for the station instead of CTD 9. CTD9's oxygen and salinity in the down profile were bad due to noisy pressure requiring heavy interpolation. ICTD 1338 data was used to make the down 2-db file. CTD 9's info was left with the bottle file. There were problems makeing the bottle file from the IR CTD. Note, there are different up and down cals!, one for CTD1338, the other for CTD9. STATION 909 CTD1344 had jumped in salinity -.002psu at 3453db. Profile continued down at this lower salinity until reaching the bottom it jumped back +.001psu. The uptrace, bottles and surrounding stations did not support this feature. The salinity below 3453 was replaced with the uptrace salinity. STATIONS 973 to 979 CTD 1344 conductivity sensor was jumping low, away from the profile and then back to the real value over these set of stations. The problem appeared to be a loose conducivity sensor that was epoxied into place after station 981. STATION 973 Replace the bad salinity with uptrace salinity over the pressure ranges 1191 to 1641 db and 1707 to 2747 db. STATION 974 Replace the bad salinity with uptrace salinity over the pressure range 1921 to 3773 db (bottom). STATION 975 Large interpolations over bad sections. The ranges are listed in the interpolation file: Station, Start pressure, 3=salinity, Ending pressure 975,939,3,1127 975,1447,3,1453 975,1455,3,1457 975,1479,3,1485 975,1781,3,1833 975,2083,3,2157 STATION 976 Interpolate over the bad section. The range is listed in the interpolation file: Station, Start pressure, 3=salinity, Ending pressure 976,2191,3,2251 STATION 977 Leave as is, there is some odd shape in the 900 to 1100 db range but it is loosley mimicked by the uptrace . STATION 979 Interpolate over bad section. The range is 2683 to 3151 db. There is some shape in the 800 to 1200 dbar section but again, it is loosely copied by the uptrace data. STATION 978, 980 to 014 CTD1338, the downtrace salinity was fit to bottles for downtrace scaling term. Uptrace left as it was. There are two cal files for each station, one for uptrace data *.CU8 and one for downtrace data *.C08. The *.CTD files of 2 db pressure averaged and centered downtrace profiles and the *.SEA bottle file both refer to stations 1000 to 1014 as 0 to 14. The *.SEA files (one for leg1 and one for leg2) have been updated with the new CTD pressure, temperature, potential temperature, salinity and oxygen data produced from the latest set of calibration coefficients. The indivdual quality of the CTD salt and oxygen observations within the *.SEA file has not been checked. The quality words for these two parameters has been left as '3' (questionable) simply to show they have not been looked at. Final nutrient data has been merged into the *.SEA files as well. _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ BOTTLE DATA CFC-11 and CFC-12 Measurements - WOCE I1 Leg 1: Muscat, Oman to Colombo, Sri Lanka Analysts: Mr. Steven Covey, University of Washington Ms. Sabine Mecking, University of Washington Leg 2: Colombo, Sri Lanka to Singapore Analysts: Mr. Steven Covey, University of Washington Ms. Wenlin Huang, University of Washington SAMPLE COLLECTION AND ANALYSIS Samples for CFC analysis were drawn from the 10-liter Niskins into100-cc ground glass syringes fitted with plastic stopcocks. These samples were the first aliquots drawn from the particular Niskins. The samples were analyzed using a CFC extraction and analysis system of Dr. Ray F. Weiss of Scripps Institution of Oceanography. The analytical system was set up in a portable laboratory, belong to Dr. John Bullister, on the fantail of the R/V Knorr. The analytical procedure and data analysis are described by Bullister and Weiss (1988). One syringe, Becton-Dickinson9882, was found to be a source of contamination for CFC-11. A separate sampling blank was applied to this syringe. These samples have been flagged as "questionable" (WOCE flag 3) and are listed below (Table 4). The CFC concentrations in air (Table 3) were measured approximately every two days during this expedition. Air was pumped to the portable laboratory from the bow through Dekabon tubing. Calibration A working standard, calibrated on the SIO1993 scale, was used to calibrate the response of the electron capture detector of the Shimadzu Mini-2 GC to the CFCs. This standard, Airco cylinder CC88110, contained gas with CFC-11 and CFC-12 concentrations of 275.61 parts per trillion (ppt) and 496.49 ppt, respectively. SAMPLING BLANKS We have attempted to estimate the level of contamination by taking the mode of measured CFC concentration in samples which should be CFC-free. In this region, measurements of other transient tracers such as carbon-14 indicate that the deep waters are much older than the CFC transient. We have used all samples deeper than 2000 meters to determine the blanks of 0.002 picomoles per kilogram (pmol/kg) for CFC-12 and 0.004 pmol/kg for CFC-11. These concentrations have been subtracted from all the reported dissolved CFC concentrations. Syringe 9882 had a much higher sampling blank for CFC-11 (0.010 +/- 0.010 pmol/kg) based on the mean of a few samples. Since there is a large uncertainty in the contamination level, all of the samples collected using this syringe during the first leg have been flagged as questionable. The stopcock (likely source of the contamination) appears to have been changed for leg 2. DATA In addition to the CFC concentrations which have merged with the .hyd file, the following three tables have been included to complete the data set. The first two are tables of the duplicate samples. The third is a table of the measured atmospheric CFC concentrations listed with time and position. Table 1: CFC-11 Concentrations in Replicate Samples STN SAMP CFC-11 WOCE STN SAMP CFC-11 WOCE NBR NO. pM/kg Flag NBR NO. pM/kg Flag --- ---- --------- ---- ---- ---- --------- ---- 859 1 10 0.003 2 899 1 1 0.003 2 859 1 10 0.007 2 902 1 16 0.208 2 862 1 24 0.812 2 902 1 16 0.211 2 862 1 24 0.822 2 909 1 21 0.026 2 863 1 25 0.100 2 909 1 21 0.025 2 863 1 25 0.098 2 912 1 9 -0.004 2 864 1 15 0.135 2 912 1 9 -0.001 2 864 1 15 0.136 2 925 1 2 0.000 2 866 1 25 0.972 2 925 1 2 0.000 2 866 1 25 0.965 2 925 1 21 0.005 2 870 1 12 0.071 2 925 1 21 0.003 2 870 1 12 0.072 2 929 1 1 0.008 2 871 1 19 0.402 2 929 1 1 0.008 2 871 1 19 0.410 2 936 1 24 0.010 2 872 1 20 0.816 2 936 1 24 0.013 2 872 1 20 0.830 2 940 1 29 0.355 2 873 1 1 0.661 2 940 1 29 0.348 2 873 1 1 0.670 2 941 1 1 0.000 2 877 1 17 0.701 2 941 1 1 0.002 2 877 1 17 0.703 2 952 1 16 0.010 2 885 1 20 0.501 2 952 1 16 0.014 2 885 1 20 0.492 2 954 1 5 -0.002 2 889 1 15 0.147 2 954 1 5 -0.003 2 889 1 15 0.146 2 1012 1 7 1.441 2 899 1 1 0.002 2 1012 1 7 1.425 2 Table 2: CFC-12 Concentrations in Replicate Samples STN SAMP CFC-12 WOCE STN SAMP CFC-12 WOCE NBR NO. pM/kg Flag NBR NO. pM/kg Flag --- ---- --------- ---- ---- ---- --------- ---- 889 1 15 0.078 2 896 1 33 1.012 2 896 1 33 1.006 2 899 1 1 -0.002 2 859 1 10 0.005 2 899 1 1 -0.002 2 859 1 10 0.011 2 902 1 16 0.111 2 862 1 24 0.476 2 902 1 16 0.111 2 862 1 24 0.482 2 909 1 21 0.014 2 863 1 25 0.054 2 909 1 21 0.013 2 863 1 25 0.044 2 912 1 9 0.000 2 864 1 15 0.070 2 912 1 9 -0.002 2 864 1 15 0.070 2 925 1 2 0.002 2 866 1 25 0.543 2 925 1 2 0.002 2 866 1 25 0.545 2 925 1 21 0.004 2 868 1 22 0.186 2 925 1 21 0.000 2 868 1 22 0.172 2 929 1 1 0.003 2 870 1 12 0.034 2 929 1 1 0.001 2 870 1 12 0.038 2 936 1 24 0.004 2 871 1 19 0.220 2 936 1 24 0.007 2 871 1 19 0.224 2 940 1 29 0.188 2 872 1 20 0.429 2 940 1 29 0.184 2 872 1 20 0.427 2 941 1 1 0.001 2 873 1 1 0.370 2 941 1 1 0.000 2 873 1 1 0.380 2 952 1 16 0.006 2 877 1 17 0.395 2 952 1 16 0.006 2 877 1 17 0.392 2 954 1 5 0.001 2 885 1 20 0.275 2 954 1 5 -0.001 2 885 1 20 0.266 2 1012 1 7 0.840 2 889 1 15 0.080 2 1012 1 7 0.831 2 Table 3: Atmospheric CFC Concentrations AIR LAT N LON E DATE TIME CFC-11 CFC-12 STNNBR NBR deg deg gmt gmt ppt ppt (approx.) --- ------ ------ ------ ---- ------ ------ ------- 1 19.082 58.797 950831 657 262.0 526.2 861 1 19.082 58.797 950831 707 261.9 523.8 861 1 19.082 58.797 950831 717 261.5 527.3 861 1 19.082 58.797 950831 726 262.1 528.8 861 2 16.267 56.555 950901 825 262.2 527.0 863 2 16.267 56.555 950901 840 262.6 527.3 863 2 16.267 56.555 950901 850 262.6 525.8 863 2 16.267 56.555 950901 900 262.4 523.7 863 2 16.267 56.555 950901 918 262.1 522.5 863 3 14.167 52.753 950903 1001 262.0 523.9 870 3 14.167 52.753 950903 1010 262.0 521.4 870 3 14.167 52.753 950903 1020 261.9 523.3 870 3 14.167 52.753 950903 1029 261.8 523.5 870 4 12.375 43.812 950905 1721 266.0 531.1 873 4 12.375 43.812 950905 1730 264.8 531.2 873 4 12.375 43.812 950905 1740 265.2 529.7 873 4 12.375 43.812 950905 1749 265.1 532.7 873 5 12.333 45.753 950906 904 263.9 531.0 877 5 12.333 45.753 950906 914 263.6 530.9 877 5 12.333 45.753 950906 923 263.7 529.3 877 5 12.333 45.753 950906 933 263.7 528.5 877 6 13.065 48.568 950907 1701 265.3 536.2 883 6 13.065 48.568 950907 1711 264.6 536.0 883 6 13.065 48.568 950907 1720 264.7 533.4 883 7 13.717 51.568 950909 1118 262.6 523.5 892 7 13.717 51.568 950909 1128 261.6 523.1 892 7 13.717 51.568 950909 1137 262.7 522.5 892 7 13.717 51.568 950909 1147 262.3 523.4 892 8 9.898 53.800 950911 32 262.8 524.7 897 8 9.898 53.800 950911 43 261.5 521.1 897 8 9.898 53.800 950911 52 261.9 522.3 897 8 9.898 53.800 950911 102 261.4 521.8 897 9 8.823 52.690 950913 802 261.9 525.6 904 9 8.823 52.690 950913 812 261.8 525.0 904 9 8.823 52.690 950913 822 261.6 523.9 904 9 8.823 52.690 950913 832 262.3 524.4 904 10 8.930 54.417 950914 1151 262.6 523.6 908 10 8.930 54.417 950914 1201 262.5 523.8 908 10 8.930 54.417 950914 1212 262.3 524.7 908 11 8.490 58.110 950916 603 262.0 525.5 916 11 8.490 58.110 950916 613 262.1 523.6 916 11 8.490 58.110 950916 624 262.3 523.4 916 11 8.490 58.110 950916 634 262.2 523.1 916 12 9.008 61.552 950918 941 262.4 524.5 925 12 9.008 61.552 950918 951 263.1 525.6 925 12 9.008 61.552 950918 1001 263.1 525.7 925 12 9.008 61.552 950918 1010 263.5 524.9 925 13 8.500 65.883 950921 258 262.9 528.6 934 13 8.500 65.883 950921 308 263.1 528.5 934 13 8.500 65.883 950921 318 263.1 526.4 934 13 8.500 65.883 950921 328 262.8 528.8 934 14 8.497 68.900 950922 2130 263.9 526.4 940 14 8.497 68.900 950922 2140 262.7 524.3 940 14 8.497 68.900 950922 2151 263.7 525.1 940 14 8.497 68.900 950922 2202 262.5 525.4 940 14 8.497 68.900 950924 40 261.9 520.6 940 14 8.497 68.900 950924 55 260.2 522.8 940 15 8.503 71.215 950924 130 262.7 528.6 944 15 8.503 71.215 950924 140 262.2 526.8 944 15 8.503 71.215 950924 149 262.0 525.0 944 15 8.503 71.215 950924 200 262.9 526.5 944 16 8.568 73.832 950925 906 262.9 525.4 951 16 8.568 73.832 950925 916 263.0 523.7 951 16 8.568 73.832 950925 926 262.7 526.5 951 17 6.417 79.100 950927 1418 263.7 527.1 958 17 6.417 79.100 950927 1428 263.7 526.7 958 17 6.417 79.100 950927 1438 264.0 526.7 958 18 5.633 79.997 950930 1242 262.9 529.2 963 18 5.633 79.997 950930 1251 261.5 528.3 963 18 5.633 79.997 950930 1301 262.7 526.9 963 19 9.963 83.847 951004 2220 265.1 532.5 978 19 9.963 83.847 951004 2231 264.8 530.5 978 19 9.963 83.847 951004 2241 265.0 528.9 978 19 9.963 83.847 951004 2252 264.4 530.6 978 20 9.828 86.788 951008 920 262.5 529.3 989 20 9.828 86.788 951008 930 264.1 531.8 989 20 9.828 86.788 951008 940 263.8 528.7 989 21 9.855 95.332 951012 230 263.2 526.8 1008 21 9.855 95.332 951012 239 263.6 526.2 1008 21 9.855 95.332 951012 250 262.8 525.0 1008 21 9.855 95.332 951012 302 263.1 526.2 1008 22 9.627 97.442 951013 21 263.9 530.7 1014 22 9.627 97.442 951013 30 263.9 528.9 1014 22 9.627 97.442 951013 41 264.1 527.8 1014 22 9.627 97.442 951013 53 263.8 526.7 1014 Table 4 - Samples Collected Using Syringe 9882 The following samples were collected with syringe 9882. Since deep samples taken with this syringe showed some contamination, a higher blank of 0.01 pmol/kg is subtracted from the samples collected during the first leg of the cruise (up to station 861). All of the samples from the first leg are also flagged as questionable (3) or bad (4). NOTE: The sample number is 100*Cast plus the bottle number. STN SAMP Nominal | STN SAMP Nominal | STN SAMP Nominal NBR Depth | NBR Depth | NBR Depth --- ---- ------- | --- ---- ------- | --- ---- ------ 857 127 3195 | 912 122 700 | 958 127 30 861 106 2600 | 913 126 400 | 964 108 1350 862 106 2000 | 914 112 2400 | 965 128 90 863 123 800 | 915 123 250 | 966 128 350 864 120 250 | 917 110 2600 | 967 128 300 868 122 300 % part of dupl. | 918 114 800 | 968 128 350 874 114 120 | 919 116 1100 | 969 123 800 879 127 30 | 920 131 90 | 971 124 150 881 110 1000 | 921 124 500 | 972 125 450 882 126 90 | 922 136 5 | 974 128 150 883 121 180 | 923 119 800 | 975 114 1500 884 114 600 | 924 119 1100 | 976 129 250 885 122 200 | 925 101 4450 | 977 126 300 887 116 20 | 926 120 1100 | 979 129 150 889 128 0 | 927 121 100 | 980 125 350 891 112 700 | 928 101 4625 | 981 125 300 892 136 5 | 929 115 2000 | 986 110 2100 893 110 2400 | 930 116 1800 | 987 126 250 894 110 2600 | 931 119 1200 | 989 131 120 895 128 300 | 932 104 4200 | 990 114 1900 896 133 90 % part of dupl. | 933 125 600 | 991 128 120 898 111 2800 | 934 124 700 | 992 128 100 899 109 3200 | 935 108 3400 | 993 126 200 900 119 60 | 936 108 3700 | 994 122 450 902 110 1100 | 937 123 900 | 995 129 90 903 123 600 | 938 107 3700 | 996 122 450 904 126 500 | 941 135 30 | 997 122 600 905 110 3400 % depth may be off | 948 124 165 | 998 126 200 906 109 3800 | 949 126 30 | 1000 112 150 907 109 3600 | 950 122 90 | 1002 113 350 908 109 3800 | 951 127 250 | 1003 128 90 909 130 200 | 952 108 1550 | 1004 126 500 910 124 700 | 953 126 90 | 1005 127 120 911 109 3400 | 955 110 800 | 1008 121 200 | | 1009 116 650 _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ DATA QUALITY EVALUATIONS DQE OF WOCE I01E HYDROGRAPHIC DATA (Arnold W. Mantyla, Sept. 27, 2001) This fall cruise started out with a short section south of Sri Lanka, repeating stations occupied six months earlier on I08; and then completed a section along 10N latitude across the southern Bay of Bengal and across the Andaman Sea. The Andaman Basin was quite uniform in characteristics and provided an excellent "calibration tank" for assessment of data precision. Salinity, oxygen and nutrients all easily met WOCE precision goals: salinity standard deviations to within .001 PSU, and oxygen and nutrient to better than 0.6%. In general, the data quality on this cruise was quite good. The following is a list of problems that were noticed, some of which may be corrected by the data originator. I did not see any description in the DOC file on the analytical methods used to analyze the water sample salinity, oxygen or nutrient samples. Those descriptions should be added to the cruise documentation file. 1. Errors in the .sum file: Sta. 966 EN - had the wrong month and day - had 0930, changed to 1001 Sta. 1007 BO - latitude was 9 04.00 - changed to 9 54.00 2. The CTD salinities and oxygens assigned to the bottle tip levels were flagged as questionable on the last 29 stations. I understand that there were problems with some of the CTD oxygen sensors and apparently the up and down CTD salinity profiles had different offsets. However, from the fairly consistent bottle minus up CTD salinity differences of just a few thousandths, if appears that the up CTD salinities could be fixed to match the bottle data reasonably well and accepted as ok. It is useful to have good CTD salinity data for levels where the water sample salinity is either missing or bad. Both T and S needed for density when O2 or nutrients are used with respect to density surfaces. 3. The water sample salinities for stations 980 and 981 were all flagged questionable, apparently on the basis of a presumed faulty ampule of Standard Sea Water (P124). Comparison of the T/S curves for these stations with a pair of stations to the west (979 and 985) and a pair of stations to the east (986 and 987) showed differences of only about .001 to .002, station 980 and 9891 slightly lower. Station 981 also agrees with the CTD salinity to typically .001 except for samples 2 to 4, which appear to have been drawn out of 1 bottle deeper than the depth assigned to the sample. I suggest that station 981 salinities be accepted as ok, except for samples 2-4, which should be left as uncertain. On Station 980, the water samples appear to be slightly low, while the CTD salinities appear to be slightly high, but I would tend to accept the uncertain flags on the water samples as done by the originators. 4. Twenty-seven different bottles were flagged as leakers at least once during the cruise; but for the most part, the water samples appeared to be ok and were not flagged. Bottles 1, 2, 23, 31, and 37 leaked more than 10 times. It would be of interest to know what caused the bottles to be flagged and add a comment in the cruise documentation report noting what was seen to result in such an unusually large number of leaking rossette bottles. 5. Several stations had some nitrite data fields filled with "-9.00", but with the data quality flag set to "2", meaning acceptable measurement. I've changed those flags to "5" to indicate data not reported. (Stas. 972,976,992, and 993.) 6. Stations 982 to 985 were repeats or overlaps of stations 974 to 979. The silicates on station 974 were about 4% higher than on sta. 982, both at the same position. The silicate profile appeared to jump on sta. 973 and then came back down on sta. 975. I suggest the data originators re-check the standard factors compared to the other stations to see if there might be a calibration error that resulted in the silicates being higher on stas. 973 and 974. For now, I would consider the silicates for those two stations to be questionable. 7. The bottom 12 silicates on sta. 996 appear to be high compared to adjacent stations and also the nearby station from I09, sta. 234. Suggest flag them uncertain unless the data originators can identify a problem with the end calibration standard. 8. Although the oxygen precision was good in the Andaman Basin stations, there are other indications that the oxygens might be suspect on this cruise. On other cruises with more than one bottle tripped in the surface mixed layer, the multiple trips agree to within the measurement precision (O2 to within 0.5um/kg). Except for oxygen that was also true for the ten or so stations on this cruise that had two bottles tripped in the mixed layer. Here, the O2's differed by 3 to 8um/kg. Also, the I01E repeats of I08 were high by about 4% (I01E higher). The mixed layer oxygen percent saturation was also unusually high for this time of year, 107.5% +/-2.6%, compared to historical values of 101 to 104%. Even a conversion error from ml/l to um/l instead of um/kg would only result in a 2.5% error. I recommend that the data originators re-check the ml/l to um/kg conversion to verify the conversion was done correctly. As the data stands now, I would regard the O2 data for this cruise as suspicious. 9. Station 969 has a temperature inversion of 0.02 deg. in the top 2 bottles while the salinities are uniform, resulting in an instability. I recommend the temperature calculations be re-examined to see if one might include a spike in the average and a better value calculated. 10. Station 976: samples 8 and 9 O2 are about the same, while the CTD O2 profile shows a gradient. It appears that both O2 samples may have been collected from the 8th bottle, so sample 9 was flagged "u". 11. Station 988: sample 8 salt and O2 are missing; the nutrients are unlikely for this depth, so were flagged "u". 12. Station 995: An O2 inversion at 401db was flagged "u", but the CTD O2 profile also shows an inversion at this depth, so it appears the O2 should be accepted as ok unless the originators have some other reason for questioning that value. The bottle was not flagged as a leaker on this station, although it was 13 other times on this leg. 13. Station 1004: Sample 36 at the surface clearly mistripped, the water samples clearly are from some other depth. The oxygen and nutrients were flagged "bad", but the bottle and salinity were accepted as ok. Both should be flagged questionable as well. 14. Station 1005: Sample 23 salt and bottle flagged doubtful, but the O2 and nutrients were accepted as ok. They should also be flagged "u". 15. Station 1009: The bottom salinity appears to be about .005 low and should be "u'ed", it would be ok if the last 2 digits had mistakenly been transposed. 16. Station 1010: From the silica profile compared to adjacent stations, it appears that samples 5 and 6 both came from the number 6 depth, and samples 3 and 4 were also assigned to one depth too deep. Therefore samples 3, 4, and 5 nutrients were flagged "u". DQE OF WOCE I01W HYDROGRAPHIC DATA (Arnold W. Mantyla, Nov. 1, 2001) This cruise started in the northwest Arabian Sea with a few stations along the coast of Oman; there they did a line of stations in the Gulf of Aden to the Red Sea entrance; followed by the main line of stations across the southern Arabian Sea from Somalia to India. The first test station tripped all 36 bottles at about 3200db. The oxygen and nutrient precision were excellent, better than 0.5% S.D., but the salinities included a few poor samples that made the precision apparently not up to WOCE specifications. However, this station was early in the cruise and I suspect that inexperienced help may have resulted in a few sampling errors. The salinities for the majority of the cruise were fine. The overall data quality was generally quite good, except for some curiously poor mixed layer oxygens. The following text lists a few problems that were noticed during the data examination. 1. Problems in the .sum file: Many stations are listed with identical positions for the BE, BO, and EN of a cast, and all 3 were coded as having been derived from a GPS fix. Only the cast time closest to the GPS fix should have that code, the rest that are assumed should have some other lower quality code, perhaps the one for dead reckoning. Sta. 890 BE Position off by 1 deg. Changed to 14 deg. Sta. 927 BE Position differs from BO and EN by 10'. Changed BE to agree with BO and EN Sta. 941 BE, BO, and EN Dates off by one day, had 0922, changed to 0923. 2. The CTD salinities and oxygens assigned to the bottle trips have all been flagged as "3, questionable measurement", or "1 analysis not received", but data are listed for all trips. Should resolve the "1" flags on this and on the following leg, as either OK or questionable. 3. Sta. 859 - NO DATA - 0-800db, all of the deep cast nutrients were poor, so I flagged them as questionable. I suggest that the nutrient standardization be re-checked to see if the data can be recovered. Sta. 863, 2db: Surface temperature is bad, need to get a good one. There are no flags for temperature. Should either get a good temperature, or delete this one. Sta. 893 - There were 4 bottles tripped in the surface mixed layer, with good agreement in all samples except for dissolved oxygen. The 3rd one was 12 micro mols higher than the other 3, so I flagged it "u". Station O2's seemed erratic at times on this and on the following leg (see comment in the I01E DQE report). Sta. 899 and 900 - The surface temperatures are unlikely cooler than the next depth down, while the salinities are uniform, resulting in instabilities. The difference is 0.2 deg C on sta. 900. Suggest re- check surface temperatures to see if the average includes any spurious data. Sta. 900, 499db - Double trip, data do not agree very well, "u'd" bottle 5 data. Sta. 901, 33db - Temperature minimum, though salts are uniform 8 to 61 db. Suggest re-check temperature calculation, would "u" it if there were a flag for temperature. Sta. 918 - Two trips at 5db, oxygens differ by 5%, can't tell which is better, so left both as ok. Sta. 934 - 3 NO2's listed as -9.00, but flagged ok. Changed flag to not reported. Problem occurs on other stations on this leg and on the next leg as well. Sta. 940 - Poor mixed layer O2 agreement, don't know which is most likely, so accepted both as is. Sta. 943 - Deep silicates are unlikely high compared to other stations. "u'd" the bottom 14 silicates, but suggest re-check end standard calculations to see if these can be salvaged. Sta. 961 - Sample 1 was listed 13 times. Deleted 12 of them. WOCE CTD Data Consistency Check: I01E About the '_check.txt', '_sal.ps' and '_oxy.ps' files: The WHP-Exchange format bottle and/or CTD data from this cruise have been examined by a computer application for contents and consistency. The parameters found for the files are listed, a check is made to see if all CTD files for this cruise contain the same CTD parameters, a check is made to see if there is a one-to-one correspondence between bottle station numbers and CTD station numbers, a check is made to see that pressures increase through each file for each station, and a check is made to locate multiple casts for the same station number in the bottle data. Results of those checks are reported in this '_check.txt' file. When both bottle and CTD data are available, the CTD salinity data (and, if available, CTD oxygen data) reported in the bottle data file are subtracted from the corresponding bottle data and the differences are plotted for the entire cruise. Those plots are the' _sal.ps' and '_oxy.ps' files. Following parameters found for bottle file: EXPOCODE SALNTY CFC-12 SECT_ID SALNTY_FLAG_W CFC-12_FLAG_W STNNBR CTDOXY TRITUM CASTNO CTDOXY_FLAG_W TRITUM_FLAG_W SAMPNO OXYGEN HELIUM BTLNBR OXYGEN_FLAG_W HELIUM_FLAG_W BTLNBR_FLAG_W SILCAT DELC14 DATE SILCAT_FLAG_W DELC14_FLAG_W TIME NITRAT TCARBN LATITUDE NITRAT_FLAG_W TCARBN_FLAG_W LONGITUDE NITRIT ALKALI DEPTH NITRIT_FLAG_W ALKALI_FLAG_W CTDPRS PHSPHT CTDRAW CTDTMP PHSPHT_FLAG_W THETA CTDSAL CFC-11 CTDSAL_FLAG_W CFC-11_FLAG_W • All ctd parameters match the parameters in the reference station. • All stations correspond among all given files. • No bottle pressure inversions found. • Bottle file pressures are increasing. • No multiple casts found in bottle data. WOCE CTD DATA CONSISTENCY CHECK: I01W About the '_check.txt', '_sal.ps' and '_oxy.ps' files: The WHP-Exchange format bottle and/or CTD data from this cruise have been examined by a computer application for contents and consistency. The parameters found for the files are listed, a check is made to see if all CTD files for this cruise contain the same CTD parameters, a check is made to see if there is a one-to-one correspondence between bottle station numbers and CTD station numbers, a check is made to see that pressures increase through each file for each station, and a check is made to locate multiple casts for the same station number in the bottle data. Results of those checks are reported in this '_check.txt' file. When both bottle and CTD data are available, the CTD salinity data (and, if available, CTD oxygen data) reported in the bottle data file are subtracted from the corresponding bottle data and the differences are plotted for the entire cruise. Those plots are the' _sal.ps' and '_oxy.ps' files. Following parameters found for bottle file: EXPOCODE SALNTY CFC-12 SECT_ID SALNTY_FLAG_W CFC-12_FLAG_W STNNBR CTDOXY TRITUM CASTNO CTDOXY_FLAG_W TRITUM_FLAG_W SAMPNO OXYGEN HELIUM BTLNBR OXYGEN_FLAG_W HELIUM_FLAG_W BTLNBR_FLAG_W SILCAT DELC14 DATE SILCAT_FLAG_W DELC14_FLAG_W TIME NITRAT TCARBN LATITUDE NITRAT_FLAG_W TCARBN_FLAG_W LONGITUDE NITRIT ALKALI DEPTH NITRIT_FLAG_W ALKALI_FLAG_W CTDPRS PHSPHT CTDRAW CTDTMP PHSPHT_FLAG_W THETA CTDSAL CFC-11 CTDSAL_FLAG_W CFC-11_FLAG_W • All ctd parameters match the parameters in the reference station. Station #858 has a CTD file, but does not exist in i01w_hy1.csv. Station #867 has a CTD file, but does not exist in i01w_hy1.csv. Station #869 has a CTD file, but does not exist in i01w_hy1.csv. Station #882 exists in i01w_hy1.csv, but does not have a corresponding CTD file. • No bottle pressure inversions found. • Bottle file pressures are increasing. • No multiple casts found in bottle data. _____________________________________________________________________________________________________________ _____________________________________________________________________________________________________________ APPENDIX A: REPRINT OF PERTINENT LITERATURE Johnson K.M., A.G. Dickson, G. Eischeid, C. Goyet, P.R. Guenther, R.M. Key, K. Lee, E.R. Lewis, F.J. Millero, D. Purkerson, C.L. Sabine, R.G. Schottle, D.W.R. Wallace, R.J. Wilke, and C.D. Winn. 2002. Carbon Dioxide, Hydrographic and Chemical Data Obtained During the Nine R/V Knorr Cruises Comprising the Indian Ocean CO2 Survey (WOCE Sections I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, I10, and I2; December 1, 1994 -January 22, 1996), Ed. A. Kozyr. ORNL/CDIAC-138, NDP-080. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee. ORNL/CDIAC-138 NDP-080 CARBON DIOXIDE, HYDROGRAPHIC, AND CHEMICAL DATA OBTAINED DURING THE NINE R/V KNORR CRUISES COMPRISING THE INDIAN OCEAN CO2 SURVEY (WOCE SECTIONS I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, I10, and I2; DECEMBER 1, 1994 JANUARY 19, 1996) Contributed by Kenneth M. Johnson,1 Andrew G. Dickson,2 Greg Eischeid,3 Catherine Goyet,4 Peter R. Guenther,2 Robert M. Key,5 Kitack Lee,6 Ernest R. Lewis,7 Frank J. Millero,6 David Purkerson,6 Christopher L. Sabine,8 Rolf G. Schottle,9 Douglas W.R. Wallace,10 Richard J. Wilke,7 and Christopher D. Winn,11 1 Department of Applied Science, Brookhaven National Laboratory, Upton, NY, U.S.A. Retired, now at P.O. Box 483, Wyoming, RI, U.S.A. 2 Scripps Institution of Oceanography, University of California, La Jolla, CA, U.S.A. 3 Woods Hole Oceanographic Institute, Woods Hole, MA, U.S.A. 4 University of Perpignan, Perpignan, France 5 Department of Geosciences, Princeton University, Princeton, NJ, U.S.A. 6 Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, U.S.A. 7 Department of Applied Science, Brookhaven National Laboratory, Upton, NY, U.S.A. 8 Pacific Marine Environmental Laboratory, NOAA, Seattle, WA, U.S.A. 9 Department of Oceanography, University of Hawaii, Honolulu, HI, U.S.A. 10 Institute for Marine Sciences, Kiel, Germany 11 Hawaii Pacific University, Kaneohe, HI, U.S.A. Prepared by Alexander Kozyr Carbon Dioxide Information Analysis Center Oak Ridge National Laboratory Oak Ridge, Tennessee, U.S.A. Date Published: October 2002 Prepared for the Environmental Sciences Division Office of Biological and Environmental Research U.S. Department of Energy Budget Activity Numbers KP 12 04 01 0 and KP 12 02 03 0 Prepared by the Carbon Dioxide Information Analysis Center OAK RIDGE NATIONAL LABORATORY Oak Ridge, Tennessee 37831-6335 managed by UT-BATTELLE, LLC for the U.S. DEPARTMENT OF ENERGY under contract DE-AC05-00OR22725 CONTENTS LIST OF FIGURES LIST OF TABLES ACRONYMS ABSTRACT PART 1: OVERVIEW 1. BACKGROUND INFORMATION 2. DESCRIPTION OF THE EXPEDITION 2.1 R/V Knorr: Technical Details and History 2.2 The Indian Ocean CO2 Survey Cruises Information 2.3 Brief Cruise Summary 3. DESCRIPTION OF VARIABLES AND METHODS 3.1 Hydrographic Measurements 3.1.1 SIO/ODF Methods and Instrumentation 3.1.2 WHOI Methods and Instrumentation 3.1.3 Underway Measurements 3.2 Total Carbon Dioxide Measurements 3.3 Total Alkalinity Measurements 3.4 Carbon Data Synthesis and Analysis 3.5 Radiocarbon Measurements 4. DATA CHECKS AND PROCESSING PERFORMED BY CDIAC 5. HOW TO OBTAIN THE DATA AND DOCUMENTATION 6. REFERENCES LIST OF FIGURES (see PDF report for figures) Figure 1 The cruise track during the R/V Knorr expeditions in the Indian Ocean along WOCE Sections I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, and I2 2 Sampling depths at all hydrographic stations occupied during the R/V Knorr Indian Ocean survey along WOCE Section I9N 3 Example of ODV station mode plot: measurements vs depth for Stations 172 174 of Section I9N 4 Distribution of the TCO2 and TALK in seawater along WOCE Section I9N 5 Property-property plots for all stations occupied during the R/V Knorr cruise along WOCE Section I9N LIST OF TABLES Table 1 Technical characteristics of R/V Knorr 2 Dates, ports of call, expedition codes (EXPOCODEs), and names of chief scientists during Indian Ocean CO2 survey cruises 3 WOCE measurement programs and responsible institutions during Indian Ocean CO2 survey cruises 4 Principal investigators and senior at-sea personnel responsible for the WOCE measurement programs during Indian Ocean CO2 survey cruises 5 Personnel responsible for carbonate system parameter measurements, number of CTD stations, and number of TCO2 and TALK analyses made during Indian Ocean CO2 survey cruises 6 Required WHP accuracy for deep water analyses 7 The short-term precision of the nutrient analyses for Indian Ocean Section I2 8 Certified salinity, TALK, and TCO2 for CRM supplied for Indian Ocean CO2 survey 9 Precision of discrete TCO2 analyses during Indian Ocean CO2 survey 10 Mean difference and standard deviation of the differences between at-sea TCO2 by coulometry and on-shore TCO2 by manometry on aliquots of the same sample from Indian Ocean CO2 survey, and mean replicate precision of the manometric analyses 11 Mean analytical difference (TALK) between analyzed and certified TALK for CRM used during Indian Ocean CO2 survey 12 Mean analytical difference (TALK) between analyzed and certified TALK for each section during Indian Ocean CO2 survey 13 Final count of carbonate system parameter (CSP) analyses during Indian Ocean CO2 survey 14 Content, size, and format of data files ACRONYMS A/D analog-to-digital ADCP acoustic Doppler current profiler ALACE autonomous Lagrangian circulation explorer BOD biological oxygen demand BNL Brookhaven National Laboratory 14C radiocarbon CALFAC calibration factor CDIAC Carbon Dioxide Information Analysis Center CFC chlorofluorocarbon CO2 carbon dioxide CTD conductivity, temperature, and depth sensor CRM certified reference material d.f. degree of freedom DIW deionized water DOE U.S. Department of Energy EEZ Exclusive Economic Zone emf electro-magnetic fields EXPOCODE expedition code FSI Falmouth Scientific Instruments fCO2 fugacity of CO2 FTP file transfer protocol GO General Oceanics GMT Greenwich mean time GPS global positioning system Hcl hydrochloric acid IAPSO International Association for the Physical Sciences of the Ocean IMET Improved METeorology I/O input-output JGOFS Joint Global Ocean Flux Study kn knots LADCP lowered ADCP LDEO Lamont-Doherty Earth Observatory MATS Miami University alkalinity titration systems NBIS Neil Brown Instrument system NCSU North Carolina State University NDP numeric data package NOAA National Oceanic and Atmospheric Administration nm nautical mile NSF National Science Foundation ODF Ocean Data Facility ONR Office of Naval Research OSU Oregon State University PC personal computer PI principal investigator POC particulate organic carbon PMEL Pacific Marine Environmental Laboratory PU Princeton University QA quality assurance QC quality control R/V research vessel RSMAS Rosenstiel School of Marine and Atmospheric Sciences SIO Scripps Institution of Oceanography SOMMA single-operator multiparameter metabolic analyzer SSW standard seawater TAMU Texas A&M University TALK total alkalinity TCO2 total carbon dioxide TD to-deliver UH University of Hawaii UM University of Miami UW University of Washington VFC voltage to frequency converter WHOI Woods Hole Oceanographic Institution WHPO WOCE Hydrographic Program Office WOCE World Ocean Circulation Experiment WHP WOCE Hydrographic Program ABSTRACT Johnson K. M., A. G. Dickson, G. Eischeid, C. Goyet, P. R. Guenther, R. M. Key, K. Lee, E. R. Lewis, F. J. Millero, D. Purkerson, C. L. Sabine, R. G. Schottle, D. W. R. Wallace, R. J. Wilke, and C. D. Winn. 2002. Carbon Dioxide, Hydrographic and Chemi- cal Data Obtained During the Nine R/V Knorr Cruises Comprising the Indian Ocean CO2 Survey (WOCE Sections I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, I10, and I2; December 1, 1994 - January 22, 1996), Ed. A. Kozyr. ORNL/CDIAC-138, NDP-080. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee. This document describes the procedures and methods used to measure total carbon dioxide (TCO2) and total alkalinity (TALK) at hydrographic stations taken during the R/V Knorr Indian Ocean cruises (Sections I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, I10, and I2) in 1994 1996. The measurements were conducted as part of the World Ocean Circulation Experiment (WOCE). The expedition began in Fremantle, Australia, on December 1, 1994, and ended in Mombasa, Kenya, on January 22, 1996. During the nine cruises, 12 WOCE sections were occupied. Total carbon dioxide was extracted from water samples and measured using single- operator multiparameter metabolic analyzers (SOMMAs) coupled to coulometers. The overall precision and accuracy of the analyses was ±1.20 µmol/kg. The second carbonate system parameter, TALK, was determined by potentiometric titration. The precision of the measurements determined from 962 analyses of certified reference material was ±4.2 µmol/kg (REFERENCE). This work was supported by grants from the National Science Foundation, the U.S. Department of Energy, and the National Oceanographic and Atmospheric Administration. The R/V Knorr Indian Ocean data set is available as a numeric data package (NDP) from the Carbon Dioxide Information Analysis Center (CDIAC). The NDP consists of 18 oceanographic data files, two FORTRAN 77 data retrieval routine files, a readme file, and this printed documentation, which describes the contents and format of all files as well as the procedures and methods used to obtain the data. Instructions for accessing the data are provided. Keywords: carbon dioxide; TCO2; total alkalinity; coulometry; gas chromatography; World Ocean Circulation Experiment; Indian Ocean; hydrographic measurements; carbon cycle. 1. BACKGROUND INFORMATION The World Ocean Circulation Experiment (WOCE) Hydrographic Program (WHP) was a major component of the World Climate Research Program. The primary WOCE goal was to understand the general circulation of the global ocean well enough to be able to model its present state and predict its evolution in relation to long- term changes in the atmosphere. The impetus for the carbon system measurements arose from concern over the rising atmospheric concentrations of carbon dioxide (CO2). Increasing atmospheric CO2 may intensify the earth's natural greenhouse effect and alter the global climate. The carbon measurements, which were carried out on the U.S. WOCE Indian Ocean cruises, were supported as a core component of the Joint Global Ocean Flux Study (JGOFS). This coordinated effort received support in the United States from the U.S. Department of Energy (DOE), the National Oceanic and Atmospheric Administration (NOAA) and the National Science Foundation (NSF). Goals were to estimate the meridional transport of inorganic carbon in a manner analogous to the estimates of oceanic heat transport (Bryden and Hall 1980; Brewer, Goyet, and Drysen 1989; Holfort et al. 1998; Roemmich and Wunsch 1985) and to build a database suitable for carbon-cycle modeling and the estimation of anthropogenic CO2 in the oceans. The global data set includes approximately 23,000 stations. Wallace (2001) recently reviewed the goals, conduct, and initial findings of the survey. This report discusses the CO2 science team effort to sample the entire Indian Ocean for inorganic carbon (Fig.1). The total CO2 (TCO2) and total alkalinity (TALK) were measured in the water column and the fugacity of CO2 (fCO2) in the surface waters [see Sabine and Key (1998) for a description of the fCO2 methods and data]. The TCO2 analytical systems were furnished and set up by Brookhaven National Laboratory under the supervision of D.W.R. Wallace and K.M. Johnson, and the alkalinity titrators were furnished and set up by the University of Miami under the supervision of F.J. Millero. During the survey, certified reference material (CRM) was used to ensure measurement accuracy. All shipboard measurements followed standard operating procedures (DOE 1994). This report focuses on TCO2 and TALK measurements. Because the team shared equipment throughout all nine cruises and so much material, including quality assessments of the data, has already appeared in the refereed literature, it will be limited to a brief summary. Published documentation appears in appendices. 2. DESCRIPTION OF THE EXPEDITION 2.1. R/V Knorr: Technical Details and History The R/V Knorr, built in 1969 by the Defoe Shipbuilding Company in Bay City, Michigan, is owned by the U.S. Navy. It was turned over to the Woods Hole Oceanographic Institution in 1971 for operation under a charter agreement with the Office of Naval Research. It was named for E.R. Knorr, a hydrographic engineer and cartographer who in 1860 held the title of Senior Civilian and Chief Engineer Cartographer of the U.S. Navy Office. Its original length and beam were 245 and 46 ft, respectively. Beginning on February 6, 1989, it underwent a major midlife retrofit or "jumbo-izing" at the McDermott Shipyard in Amelia, Louisiana. A midsection was added to the ship to stretch its length by 34 ft, to 279 ft, and fore and aft azimuthing propulsion systems were added to make it one of the most maneuverable and stable ships in the oceanographic fleet. By the time it was returned to the Woods Hole Oceanographic Institution in late 1991, the retrofit had taken 32 months. The P6 Section was the vessel's first scientific cruise after the retrofitting. The R/V Knorr was designed for a wide range of oceanographic operations and possesses antiroll tanks and a strengthened bow for duty in icy waters. Like its sister ship, the R/V Melville, it is used for ocean research and routinely carries scientists from many different countries. Table 1 provides a list of technical characteristics of the R/V Knorr, while Table 2 provides individual cruise information, parameters measured, and responsible personnel with their institutional affiliations. 2.2. The Indian Ocean CO2 Survey Cruises Information Ship name: R/V Knorr Cruise/Leg: WOCE Sections I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, I10, and I2 Ports of call: Fremantle Australia (start), and Mombasa, Kenya (end) Dates: December 1, 1994 - January 22, 1996 TALK instrumentation: F.J. Millero, RSMAS TCO2 instrumentation: D.W.R. Wallace and K.M. Johnson, Brookhaven National Laboratory (BNL) Reference material: A.D. Dickson, SIO Funding support: DOE, NSF Chief scientist: See Table 2 TABLE 2: Dates, ports of call, expedition codes (EXPOCODEs), and names of chief scientists during Indian Ocean CO2 survey cruises _________________________________________________________________________________________ Section Start Finish From To EXPOCODE Chief date date Scientist ------- -------- -------- ---------- ---------- ------------ ------------------- I8SI9S 12/01/94 01/19/95 Fremantle Fremantle 316N145_5 M. McCartney (WHOI) I9N 01/24/95 03/06/95 Fremantle Colombo 316N145_6 A. Gordon (LDEO) I8NI5E 03/10/95 04/16/95 Colombo Fremantle 316N145_7 L. Talley (SIO) I3 04/20/95 06/07/95 Fremantle Port Louis 316N145_8 W. Nowlin (TAMU) I5WI4 06/11/95 07/11/95 Port Louis Port Louis 316N145_9 J. Toole (WHOI) I7N 07/15/95 08/24/95 Port Louis Muscat 316N145_10 D. Olson (RSMAS) I1 08/29/95 10/18/95 Muscat Singapore 316N145_11,12 J. Morrison (NCSU) Dry Dock 10/19/95 11/05/95 Dampier I10 11/06/95 11/24/95 Dampier Singapore 316N145_13 N. Bray (SIO) I2 11/28/95 01/22/96 Singapore Mombasa 316N145_14,15 G. Johnson (PMEL) _________________________________________________________________________________________ Participating Institutions: LDEO Lamont-Doherty Earth Observatory NCSU North Carolina State University PMEL Pacific Marine Environmental Laboratory RSMAS Rosenstiel School of Marine and Atmospheric Science SIO Scripps Institution of Oceanography WHOI Woods Hole Oceanographic Institution The extent and nature of the complete measurement program and the responsible institutions for each cruise are summarized in Table 3. TABLE 3: WOCE measurement programs and responsible institutions during Indian Ocean CO2 survey cruises ________________________________________________________________________ Program Section/Cruise I8SI9S I9N I8NI5E I3 I5WI4 I7N I1 I10 I2 ----------- ------ ---- ------ ---- ----- ---- --- ---- ---- Responsible institution(a) ----------- --------------------------------------------------------- CTD/Rosette WHOI ODF ODF ODF ODF ODF WHOI ODF WHOI BTL Oxygen WHIO ODF ODF ODF ODF ODF WHOI ODF WHOI BTL Salts WHOI ODF ODF ODF ODF ODF WHOI ODF WHOI Nutrients OSU ODF ODF ODF ODF ODF OSU ODF OSU CFCs LDEO UM LDEO SIO UW UM UW UM PMEL He/Tr LDEO WHOI WHOI WHOI WHOI UM WHOI WHOI WHOI Deep He/Tr LDEO LDEO UM WHOI LDEO 14C UW PU PU PU PU PU PU PU PU ADCP UH UH UH OSU UH UH SIO SIO UH TCO2, TALK BNL PU UH RSMAS BNL UH SIO SIO UH ________________________________________________________________________ (a) Participating institutions: BNL Brookhaven National Laboratory LDEO Lamont-Doherty Earth Observatory NCSU North Carolina State University PMEL Pacific Marine Environmental Laboratory ODF Ocean Data Facility (SIO) OSU Oregon State University PU Princeton University RSMAS Rosenstiel School of Marine and Atmospheric Science (UM) SIO Scripps Institution of Oceanography, Univ. of California, San Diego TAMU Texas A&M University UH University of Hawaii UM University of Miami UW University of Washington WHOI Woods Hole Oceanographic Institute The principal investigators (PIs) and the senior technical staff for the WOCE measurements program are summarized in Table 4. TABLE 4: Principal investigators and senior at-sea personnel responsible for WOCE measurement programs during Indian Ocean CO2 survey cruises __________________________________________________________________________________ Program Responsible personnel (Institution) ------------- ----------------------------------------------------------------- CTD/Rosette James Swift (SIO/ODF), John Toole (WHOI), Frank Delahoyde (SIO/ODF), Carl Mattson (SIO/ODF), Marshall Swartz (WHOI), Laura Goepfert (WHOI) Bottle oxygen James Swift (SIO/ODF), John Toole (WHOI), George Knapp (WHOI), John Boaz (SIO/ODF) Bottle salts James Swift (SIO/ODF), John Toole (WHOI), George Knapp (WHOI) Nutrients Louis Gordon (OSU), James Swift (SIO/ODF), Marie-Claude Beaupre (ODF), Joe Jennings (OSU) CFCs John Bullister (PMEL), Rana Fine (RSMAS), William Smethie (LDEO), Mark Warner (UW), Ray Weiss (SIO), Kevin Sullivan (RSMAS), Frederick A. Van Woy (SIO) He/Tr William Jenkins (WHOI), Peter Schlosser (LDEO), Zafer Top (RSMAS), Peter Landry (WHOI) 14C Robert Key (PU) ADCP Teri Chereskin (SIO), Peter Hacker (UH), Eric Firing (UH), Mike Kosro (OSU) TCO2, TALK See Table 5 __________________________________________________________________________________ Table 5 contains a summary of the personnel responsible for the discrete carbon- ate system measurements. TABLE 5: Personnel responsible for carbonate system parameter measurements, number of CTD stations, and number of TCO2 and TALK analyses made during Indian Ocean CO2 survey cruises ______________________________________________________________________ Section Institution PI(s) Group Stations TCO2 TALK Leader (No.) (No.) (No.) ------- ----------- ---------- ---------- -------- ----- ---- I8SI9S BNL D. Wallace K. Johnson 147 2184 1910 K. Johnson I9N PU R. Key C. Sabine 131 2511 2504 C. Sabine I8NI5E UH C. Winn C. Winn 166 2419 2421 I3 RSMAS F. Millero D. Purkerson 120 1734 1810 I5WI4 BNL D. Wallace R. Wilke 136 1991 1831 K. Johnson I7N UH C. Winn R. Schottle 156 2235 2577 I1 WHOI C. Goyet G. Eischeid 158 2400 2387 I10 PU R. Key C. Sabine 61 927 926 C. Sabine I2 UH C. Winn R. Schottle 168 2562 2562 -------------------------------------------------------------------- Total 1244 18963 18928 ______________________________________________________________________ 2.3. Brief Cruise Summary Unlike other CO2 survey cruises where a single institution was responsible for all phases of the work, these cruises were a group effort in which the measurement groups used the same ship and instrumentation for a 14-month period. BNL supplied two single-operator multiparameter metabolic analyzers (SOMMA) systems [S/N 004(I) and 006(II)] that were certified at BNL. A complete back-up system (S/N 023) was supplied by WHOI. The alkalinity titrators were supplied by RSMAS. Preparation began with a 4-day workshop held in September 1994 at RSMAS under the direction of and in the laboratory of F.J. Millero. Cruise participants and group leaders from BNL, LDEO, SIO, RSMAS, PU, WHOI, and UH were instructed in the use of the alkalinity titrators by F.J. Millero and D. Campbell and in the use of the SOMMA-coulometer systems by K.M. Johnson and R.W. Wilke. The day after Thanksgiving the BNL and RSMAS TCO2 groups left for Australia. Setup of the alkalinity and coulometric titration systems began on November 28, 1994. The I8SI9S cruise began on December 1, 1994. The first of the nine cruises on the R/V Knorr was the longest continuous cruise during the survey. It occupied a series of CTD stations along two north-south tracks essentially proceeding from Australia to the ice edge (I8S) along 90°E and then back again to Australia (I9S) at approximately 110°E. Station spacing ranged from 5 to 40 nautical miles (nm). Testing and selection of the best of the available titration systems and components was completed during I8S. The alkalinity and especially the coulometric titration systems benefited from This "shake-out" period. Components damaged during transit were identified and repaired or replaced. By the beginning of the I9S, operations were more or less routine. Except for one approximately 12-h period when high winds of ~60 knots (kn) made sampling impossible, work proceeded pretty much on schedule during the 50-day cruise. During the cruise the ability of a team of four marine mammal and bird observers onboard from PMEL, under the direction of C. Tynan, to remain in the cold weather and identify whales that were little more than blips on the horizon amazed all participants of the expedition. Both Christmas and New Year holidays were celebrated aboard the ship. The fine Christmas dinner was highlighted by the appearance of three humpback whales, who put on a spectacular display, jumping and passing under and about the ship. The ship docked in Fremantle, to the relief of the CO2 team members, on January 19, 1995, after 147 stations were occupied. Measurement crews were exchanged, and the new team brought along some badly needed spare parts and components. The ship departed Fremantle for I9N on January 24 with A. Gordon as Chief Scientist and a CO2 measurement group from PU. This section was basically a northward continuation of I8S. The weather was perfect during all 43 days of the cruise. The participants celebrated the equator crossing on February 14. This cruise ended on March 5 in Colombo, Sri Lanka, with 131 stations logged. During the stopover, the carrier gas supply for the coulometric titrators was shifted from bottled high purity nitrogen to a calibration gas generator (Peak Scientific), which supplied CO2-free carrier gas for the remaining of the cruises. I8NI5E began in Colombo on March 10 with L. Talley as chief scientist and a CO2 measurement group from UH on board. No problems were noted for the sampling program, and the weather remained excellent for most of this leg. The ship track proceeded southward from Sri Lanka along 88°E to 24°S, then angled southeastward to the junction of the Ninety-East Ridge and Broken Ridge. Next, the ship followed a 1987 section along approximately 32°S. This zonal section included the Central Indian Basin, and crossed the northward flow of deep water just west of Australia. Due to the good weather, some extra sampling was carried out, and by the time the ship docked in Fremantle on April 15, 166 stations had been occupied. On station 296, the rosette accidentally hit bottom at 3630 m, but the cast was successfully completed. A postcruise inspection showed no apparent damage to the equipment. This cruise included sampling for particulate organic carbon (POC) in the surface waters near the equator. POC samples were also taken at 65 stations for 13C/12C analyses. Between April 15 and 23, measurement crews were exchanged and spare parts inventories were updated. On April 23, the R/V Knorr departed Fremantle for section I3 with W. Nowlin as chief scientist and a CO2 measurement group from RSMAS. The ship had to detour almost immediately back to Fremantle for a medical emergency. The injured analyst was able to rejoin the ship in Port Louis, Mauritius. In addition to the CTD work, this cruise included the deployment of current meters, drifters, and autonomous Lagrangian circulation explorer (ALACE) floats. The cruise track ran along 20°S from Australia to Mauritius to Madagascar, crossing the West Australian Basin, Ninety-East Ridge, Central Indian Basin, and Central Indian Ridge before veering southward to 22 S around Rodrigues Island. After this, it proceeded to the east coast of Mauritius, where a 2-day port stop was made in Port Louis. Returning to sea, the ship continued sampling westward along 20°S from the continental shelf to Madagascar. Weather was characterized by southeasterly winds of 10-20 kn, mostly sunny skies, occasional rain squalls, and 4-6 ft swells with slightly higher winds and seas in mid-May. The Knorr returned to Port Louis, Mauritius, on June 5 with 120 stations logged. The next cruise, I4I5W, began on June 11 with J. Toole as chief scientist and a CO2 measurement group from BNL on board. This leg focused on major circulation features of the southwest region of the Indian Ocean, including the region where the Agulhas Current originates and where dense waters filtering through fractures in the Southwest Indian Ridge form a northward deep boundary current east of Madagascar. The cruise track formed a closed box to aid in deducing the absolute circulation. A stop was made in Durban, South Africa, on June 21 to pick up a replacement drum of CTD wires. Attempts were also made to repair the ship's bow thruster, which had failed very early in the leg; although the repair was not successful, the lack of a bow thruster had no effect on the scientific work. The R/V Knorr departed Durban on June 22 and began I5W including reoccupation of stations where data had been taken in 1987. Bad weather was experienced on June 30 when wind gusts of 40-50 kn and high seas slowed winch operations. As the ship moved across the Madagascar Basin toward port, station spacing was decreased to 20 nm. When the ship arrived in port on July 11, 136 stations had been occupied 20 more than planned. After four days in port, the R/V Knorr departed on I7N with D. Olson as chief scientist and a CO2 measurement group from UH. The director of the U.S. WOCE office, Piers Chapman, was aboard and served as a salt analyst during the section. I7N was designed to define the water mass properties and transports across the Mascarene Basin and to measure water mass properties and baroclinic structure on a short section across the Amirante Passage, located between the Mascarene and Somali Basins. It included a cross-equatorial section and a reoccupation of stations previously sampled to confirm water mass flows. This work included sampling along 65°E in the central Arabian Basin. The concluding phase of the cruise was a deep line of stations up the center of the Gulf of Oman. The last station of this phase was in the Strait of Hormuz, and it identified inflows of Arabian (Persian) Gulf water into the Arabian Basin. The cruise terminated on August 24 in Muscat, Oman, with 156 stations occupied. After a 5-day layover, the R/V Knorr departed Muscat on I1 with J. Morrison as chief scientist and a CO2 measurement group from WHOI. I1 was the northernmost Indian Ocean section. It enclosed the Arabian Sea and Bay of Bengal, which are important sources of salt and fresh water, respectively. The Knorr proceeded from Muscat to the southern end of the Red Sea and then to the coast of Somali, where the zonal section started at a nominal latitude of 8°N. The section crossed the Arabian Sea, in part to study the carbon transport in and out of the Arabian Sea, and ended on the continental shelf of India. After a brief port stop in Colombo, Sri Lanka, on September 28-30, the leg continued from the Sri Lankan shelf across the Bay of Bengal to the Myanmar continental shelf. CTD problems caused considerable difficulty for the scientific party and resulted in a somewhat noisy hydrographic data set compared to data obtained from the other sections. After the last station on the Myanmar shelf, the Knorr deadheaded to Singapore, arriving on October 16 with 158 stations logged. I1 was not only the northernmost section, it was clearly the most adventurous. ALACE float deployments had to be canceled in the territorial waters of India because the Indian observer on board refused to allow them, and then the threat of pirates caused the cancellation of a planned section across the Gulf of Aden. In the vicinity of Colombo, the ship had to be escorted by four Sri Lankan gunboats, and planned stops at stations over the Trincomalee Canyon could not be taken because of the threat of attack by the Tamil Tigers. Nevertheless, the Knorr was able to coordinate scientific activities and physical oceanographic measurements with the nearby R/V Meteor (F. Schott, chief scientist) in an area of German current meter moorings near Socotra. Sampling during I1 enabled comparison of bottle and TCO2 data with earlier JGOFS results and Meteor Pegasus and Knorr lowered acoustic Doppler current profiler (LADCP) horizontal velocities. From Singapore, the Knorr proceeded to Dampier, Australia, where it was placed in dry dock from October 19 until November 5. With the R/V Knorr back in the water, the I10 CO2 measurement group from PU arrived. This group was required to do some additional work not normally part of the crew exchange routine. During the dry dock period, the CO2 instrumentation had been depowered, and the measurement group had to repower and check the instrumentation. Some minor repairs were required for the coulometric titrators, including the replacement of one or two solenoid valves (the only valves replaced during the cruises). In addition, the sample pipettes and coolant lines were dismounted and cleaned of algal growth. The R/V Knorr departed Dampier, Australia, on November 11 with N. Bray as chief scientist. WOCE Section I10 was set to run from Shark Bay, Western Australia, to the Indonesian Exclusive Economic Zone (EEZ) 120 nm south of Sunda Strait. However, constraints imposed by the Indonesian government caused the endpoint to be moved from the Sunda Strait to near central Java. The Knorr was not granted permission to enter the EEZ of Indonesia, and concluding stations had to be taken along the boundary of the EEZ. These restrictions prevented full resolution of the South Java current. Throughout the Indian Ocean survey, bottle casts were normally made to within 5-20 m of the bottom; however, on I10 four stations over the Java Trench this could not be done. Instead, the casts were made to the maximum CTD depth of 6000 m. The quality of the bottle data was considered to be excellent throughout with very few mis-trips. ALACE floats were also released during this cruise. A festive Thanksgiving was celebrated aboard the ship, and after the last station (1075), the Knorr steamed to Singapore, arriving on November 28, with 61 stations logged. The R/V Knorr departed Singapore on December 2 for the last Indian Ocean WOCE section, I2, with G. Johnson as chief scientist and the UH CO2 measurement group aboard. Again, clearance for work in the Indonesian EEZ was not available, and after a 3-day steam, work commenced with a reoccupation of the final station of the I10 Section (station 1075). The Knorr skirted the Indonesian EEZ and moved westward, crossing the Ninety-East Ridge and the Chagos-Laccadive Ridge. The ship continued at approximately 8°S until it made a brief port call in Diego Garcia from December 28-30. At this point, the chief scientist departed the ship and was replaced by Bruce Warren, accompanied by two Kenyan observers. The Knorr returned to the 8°S line, passing the crest of the Central Indian Ridge and then the Mascarene Plateau before it turned southwestward and crossed the Amirante Passage on the way to the northern tip of Madagascar. Rounding the tip, the ship headed northwest toward Africa, making a dogleg to avoid the Tanzanian EEZ. After completing the final Indian Ocean Survey station 1244, it proceeded to Mombasa, arriving on January 22, 1996, with 168 stations logged. For inorganic carbon, the principal analytical problems for the cruise centered on the breakage of glass components in the alkalinity titrators; resupply; accumulation of bubbles in the acid lines of the alkalinity titrators; damaged coulometric cathode electrodes; algal growth in the sample lines, baths, pipettes, and alkalinity cells; wide swings in laboratory temperature (19-33 C), and the failure of the TCO2 glassware drying oven. Fortunately, glassware drying oven was repaired. Temperature swings (21-29 C) were also noted for the salinometer and nutrient laboratories. The most vexing problem for the inorganic carbon analysts was the failure of the refrigerated baths used by both the alkalinity and coulometric titration systems. The baths had to be constantly jury-rigged so that one bath did the work of two, repaired by ship's technicians when possible, or replaced when possible. The two groups used almost 12 different baths, and by the time the work ended, not one could be considered in reliable condition. Some were never repaired, while others were repaired and used for the North Atlantic survey in 1997. 3. DESCRIPTION OF VARIABLES AND METHODS 3.1. Hydrographic Measurements During the survey, responsibility for hydrographic and bottle data was divided between ODF and WHOI. Each of these groups uses or may use different procedures. Hence, the hydrographic measurements are described in separate sections. Because the greater number of the cruises were made under the auspices of SIO/ODF, the bulk of the methods description is provided in Sect. 3.1.1. Information specific to WHOI is given in Sect. 3.1.2; in this section however, the discussion is limited to significant differences between the SIO/ODF and WHOI operations or methods. Unless otherwise stated in Sect. 3.1.2, material presented in Sect. 3.1.1 applies to all cruises. Sect. 3.1.3 contains a brief description of the underway measurements common to all cruises. 3.1.1 SIO/ODF Methods and Instrumentation Hydrographic measurements consisted of salinity, dissolved oxygen, and nutrient (nitrite, nitrate, phosphate, and silicate) samples collected from Niskin bottles filled during CTD/rosette casts, and temperature, pressure, salinity, and dissolved oxygen from the CTD. At 5- to 40-nm intervals, depending on the topography, hydrographic casts were made to within 5 20 m of the bottom with a 36-bottle Rosette frame belonging to ODF. This unit consisted of a 36-bottle frame, thirty six 10-L bottles, and a 1016 General Oceanics (GO) 36-place pylon. The GO pylon was used in conjunction with an ODF-built deck unit and power supply. The underwater components comprising the CTD included an ODF-modified Neil Brown Instrument Systems (NBIS) Mark III CTD with conductivity, pressure, oxygen, and temperature sensors. The underwater package also consisted of a SeaTech transmissometer, an LADCP, a Sensormedics dissolved oxygen sensor, a Falmouth Scientific Instruments (FSI) secondary PRT sensor, a Benthos altimeter, and a Benthos pinger. The CTD was mounted horizontally along the bottom of the frame, while the LADCP was vertically mounted inside the bottle rings. The system was suspended from and powered by a three- conductor 0.322-in. electromechanical cable. The Rosette was deployed from the starboard side using either the port side Markey CTD or the starboard side Almon Johnson winch. Standard CTD practices (i.e., soaking the conductivity and O2 sensors in distilled water between casts and protecting the sensors against sunlight and wind by storing the rosette in the hanger between casts) were observed throughout the cruises. Regular CTD maintenance included the replacement of O- rings when needed, bottle inspections, and a regular cleaning of the transmissometer windows. At the beginning of each station the time, position, and bottom depth were logged. The CTD sensors were powered and control was transferred to the CTD acquisition and control system in the ship's laboratory. The CTD was lowered to within 10 m of the bottom if bottom returns were adequate. Continuous profiles of horizontal velocity from the sea surface to the bottom were made for most CTD/rosette casts using the LADCP. The CTD's control and acquisition system displayed real-time data [pressure, depth, tem- perature, salinity (conductivity), oxygen, and density] on the video display of a SunSPARC LX computer. A video recorder was provided for real-time analog backup. The Sun computer system included a color display, a keyboard, a trackball, a 2.5-GB disk, 18 RS-232 ports, and an 8-mm cartridge tape. Two additional Sun systems were networked for display, backup, and processing. Two HP 1200 C color ink-jet printers provided hard copy. The ODF data acquisition software not only acquired the CTD data but also processed it so that the real- time data included preliminary sensor corrections and calibration models for pressure, temperature, and conductivity. The sampling depths were selected using down-cast data. Bottles were tripped on the up-cast. Bottles on the rosette were identified with a serial number and the pylon tripping sequence, 1- 36, where the first (deepest) bottle tripped was no. 1. For shallow-depth stations, fewer than 36 bottles were closed. After the CTD was on deck, the acquisition system, the CTD, the pylon, and video recording were turned off and the sensor protective measures were completed before sampling began. If a full suite of samples was drawn, the sampling order was CFCs, 3He, O2, TCO2, TALK, 14C, 3H, nutrients, and salinity. Only salinity, O2, and nutrients were measured at every station. A deck log was kept to document the sampling sequence and to note anomalies (e.g., status of bottle valves, leaks, etc.). One member of the sampling crew was designated the "sample cop," and it was his or her responsibility to maintain this log and to ensure that the sampling order was followed. Oxygen sampling included measurement of the temperature, which proved useful for determining leaking or mis-tripped bottles. Following the cruises, WHP quality flags were assigned according to the WOCE Operations Manual (Joyce and Corry 1994) to each measured quantity. The principal ODF CTD (no. 1) was calibrated for pressure and temperature at the ODF Calibration Facility (La Jolla, Calif.) in December 1994 prior to the five consecutive WOCE Indian Ocean sections beginning with I9N and ending with I7N. The CTD was also calibrated postcruise in September 1995 prior to the I10 cruise. Pre- and postcruise laboratory calibrations were used to generate tables of corrections, which were applied by the CTD data. At sea, bottle salinity and oxygen data were to calibrate or check the CTD sensors. Additional details concerning calibration and the CTD data processing can be obtained from the chief scientists' cruise reports at the WHPO web site: http://whpo.uscd.edu/. Bottle salinity samples were collected in 200-mL Kimax high alumina borosilicate bottles, sealed with custom-made plastic insert thimbles and Nalgene screw caps. Salinity was determined after equilibration in a temperature-controlled laboratory, usually within 8-20 h of collection. Salinity was measured with two ODF-modified Guildline Autosal Model 8400A salinometers, normally at 21 or 24°C, depending on the prevailing temperature of the salinometer laboratory. The salinometers included interfaces for computer-aided measurements (e.g., acquiring the measurements, checking for consistency, logging results, and prompting the analyst). The salinometers were standardized with International Association for the Physical Sciences of the Ocean (IAPSO) Standard Seawater (SSW) Batches P-124, P-126, or P-128 using at least one fresh vial per cast (usually 36 samples). The accuracy of the determination was normally 0.002 relative to the SSW batch used. PSS-78 was then calculated for each sample (UNESCO 1981). On some stations (e.g., on Section I5EI8N), bottle salinity exhibited small offsets (0.002 0.004) compared to the corresponding CTD results and bottle salinity from nearby stations, and corrections of this magnitude need to be applied to the bottle salinity. Errors of this magnitude have no practical effect on the calculated TCO2 or TALK values. Hence, bottle salinity is sufficiently accurate to express inorganic carbon results in µmol/kg. Bottle oxygen was determined by rinsing 125-mL iodine flasks twice and then filling to overflowing (3x-bottle volume) with a draw tube. Sample temperature was measured immediately with a thermometer imbedded in the draw tube. The Winkler reagents were added; and the flask was stoppered, shaken, and then shaken again 20 min later to ensure that the dissolved O2 was completely fixed. Oxygen was determined within 4 h of collection using a whole-bottle modified Winkler titration following the technique of Carpenter (1965) and incorporating the modifications of Culberson et al. (1991) on an SIO/ODF-designed automated oxygen titrator. A Dosimat 665 burette driver fitted with a 1.0-mL burette was used to dispense thiosulfate solution (50 g/L). Standards prepared from preweighed potassium iodate (0.012N) were run each time the automated titrator was used, and reagent blanks were determined by analyzing distilled water. The final oxygen results were converted to µmol/kg using the in situ temperature. Bottle volumes were precalibrated at SIO. Laboratory temperature stability during the sections was considered poor, varying from 22 to 28°C over short time periods; and therefore, portable fans were used by ODF analysts to maintain temperature. Phosphate, nitrate, nitrite, and silicate samples were collected in 45-mL high- density polypropylene, narrow-mouth, screw-capped centrifuge tubes which were cleaned with 10% hydrochloric acid (HCl) and then rinsed three times with sample before filling. The samples were analyzed on an ODF-modified four-channel Technicon AutoAnalyzer II, usually within 1 h of the cast, in a temperature- controlled laboratory. If the samples were stored for longer than 1 h prior to analysis, they were stored at 2 6°C (for no more than 4 h). The AutoAnalyzer incorporates the method of Armstrong, Stearns, and Strickland (1967) for silicate, this same method as modified for nitrate and nitrite, and the method of Bernhardt and Wilhelms (1967) for phosphate. The last method is described by Gordon and coworkers (Atlas et al. 1971; Hager et al. 1972; and Gordon et al. 1992). Standards were analyzed at the beginning and end of each group of sample analyses, with a set of secondary intermediate concentrations prepared by diluting preweighed primary standards. Replicates were also drawn at each station for measurement of short-term precision. For reagent blanks, deionized water (DIW) from a Barnstead Nanopure deionizer fed from the ship's potable water supply was analyzed. An aliquot of deep seawater was run with each set of samples as a substandard. The primary standard for silicate was Na2SiF6; and for nitrate, nitrite, and phosphate the standards were KNO3, NaNO2, and KH2PO4, respectively. Chemical purity ranged from 99.97% (NaNO2) to 99.999% (KNO3). Most hydrographic data sets met or exceeded the WHP requirements. Some exceptions for silicate were noted when differences between overlapping stations on I3 (Station 548) and I4I5W (Stations 705 and 574) approached 3%; these silicate data (Stations 702-707) were corrected by adding 3% to the original results. Instrument problems also caused difficulties for the nitrite and silicate analyses on many of the I2 cruise stations. Silicate problems were noted at some 30% of these stations, with errors typically being on the order of 2 4%. This required considerable post- cruise evaluation and workup before the desired between-station precision for deep water values of 1% was attained. However, users of the I2 silicate data are urged to use caution or to contact the analysts for assistance. Because of the difficulties with the nutrient analyses on the I2 cruise, the post-cruise I2 precision is given in Table 7 as a "worst case" for comparison with the WHP standards shown in Table 6. Short-term precision is the absolute mean difference between replicates analyzed within a sample run; the standard deviation of the differences is also shown. The authors know of no remaining CTD problems, that would affect the quality of the carbonate system data. TABLE 6: Required WHP accuracy for deep water analyses ___________________________________________ Parameter Required accuracy --------- ------------------------------ Salinity 0.002 relative to SSW analysed Oxygen 1% (2 µmol/kg) Nitrate 1% (0.3 0.4 µmol/L) Phosphate 1% (0.02 0.03 µmol/L) Silicate 1% (1 5 µmol/L) ___________________________________________ TABLE 7: The short-term precision of the nutrient analyses for Indian Ocean Section I2 ______________________________________ Parameter Difference ± St. Dev. (µmol/L) ------------ ---------- ---------- Nitrate 0.123 0.093 Phosphate 0.015 0.009 Silicic Acid 0.440 0.260 ______________________________________ 3.1.2 WHOI Methods and Instrumentations Unless otherwise stated procedures are as described in Sect. 3.1.1, above. For the hydrographic work on I8SI9S, I1, and I2, the R/V Knorr was outfitted with equipment belonging to both WHOI and SIO/ODF. For the I8SI9S section a NBIS CTD was used. For I1, four CTDs were available. The primary sensors were two new FSI CTDs belonging to WHOI with a Sensormedics oxygen sensors, a titanium pressure transducer, and a temperature monitor. The secondary sensors were two NBIS Mark-III CTDs (WHOI Nos. 9 and 12) also with a Sensormedics oxygen sensor, a titanium pressure transducer, and a temperature monitor. The MKIII CTDs experienced failures early during I1 (Stations 858 and 864), and the bulk of the hydrography was carried out using the FSI (Nos. 1338 and 1344) CTDs. Usually, the frame was set up with the two CTDs - one configured to send data up the wire and one configured to record data internally. Electrical modifications had to be made to the CTDs and the deck controllers before CTD data dropouts were eliminated and the confirmation of bottle closure from the pylon was restored. For the CTDs, a FSI DT-1050 deck unit was initially used to demodulate the data, but this unit was replaced for most of the cruise with an EG&G MK-III deck unit. These units fed serial data to two personal computers (PCs) running EG&G CTD acquisition software, with one displaying graphical output and the other a running data listing. After each station, the CTD data were forwarded to another set of PCs running EG&G postprocessing and software modified by WHOI (Millard and Yang 1993) in which the data were centered into 2 dbar bins for data quality control, which included fitting to bottle salinity and oxygen results. The CTDs were calibrated before and after the cruise for temperature and pressure at WHOI by M. Swartz and M. Plueddemann. Both calibrations were consistent, but the data set for I1 was considered to be only of fair quality because noise levels in the data set are somewhat larger than typical for other CTDs. For example, this data set has a salt noise level of 0.002 which is 2 times larger than the norm. Residuals between the bottle and profile data range from 0.001 to 0.004. For a detailed discussion of the CTD calibration and problems experienced at sea during I1, consult the chief scientist's cruise report on the WHPO web site. For I2, WHOI CTD No. 9, a WHOI-modified NBIS MK-IIIb, was used. The CTD incorporated a Sensormedics oxygen sensor, titanium pressure transducer, and temperature sensor, which were calibrated in November 1995 immediately before the cruise. On most stations, one of the FSI CTDs was used in the memory mode and downloaded after station sampling to provide independent or backup CTD traces. An FSI Ocean Temperature Module was also attached to the MK-III and CTDs. The Mark-III CTD data were acquired using an NBIS Mark-III deck unit/display that provided demodulated data to two PCs, as described for the Section I1 cruise. A PC was also devoted to recovering the data from the FSI CTDs. Post-cruise calibration, including dunk tests of the CTDs, was completed in April and May of 1996 in the WHOI calibration laboratory. The procedure of Millard and Yang (1993) was used to correct the pressure temperature sensor calibration post-cruise to eliminate down/up pressure historesis. Multiple regression fits of the CTD data to the bottle data were used to calibrate the oxygen and conductivity sensors. See the chief scientist's report on the WHPO web site for further details. Bottle salinity samples were collected in 200-mL glass bottles with removable polyethylene inserts and caps. Then they were removed to a temperature- controlled van at 23 C and analyzed on a Guildline Autosal Model 8400B salinometer (WHOI No. 11). The salinometer was standardized once a day using IAPSO SSW (128, dated July 18, 1995). The accuracy was ~0.002. A complete description of the WHOI measurement techniques is given by Knapp, Stalcup, and Stanley (1990). Bottle oxygen was determined according to procedures given by Knapp, Stalcup, and Stanley (1990). WHOI used a modified Winkler technique similar to that described by Strickland and Parsons (1972). The oxygen reagents and bi-iodate standard were prepared at WHOI in August 1994. There was no evidence that the reagents or standard deteriorated during the 17 months they were aboard the Knorr. Standardization of the thiosulphate titrant was made daily. The accuracy of the method was 0.5%, or approximately 1.0 µmol/kg. The nutrients were analyzed as described in Sect. 3.1.1 (see also Gordon et al. 1994). 3.1.3. Underway Measurements Navigational data (heading, speed, time, date, and position) were acquired from the ship's Magnavox MX global positioning system (GPS) receiver via RS-232 and logged automatically at 1-min intervals on a SunSPARC station. Underway bathymetry was logged manually at 5-min intervals from the hull-mounted 12-kHz echo sounder and a Raytheon recorder corrected according to methods described by Carter (1980). These data were merged with the navigation data to provide a time-series of underway position, course, speed, and bathymetry data that were used for all station positions, depths, and vertical sections. The Improved METeorology (IMET) sensors logged meteorological data which included air temperature, barometric pressure, relative humidity, sea surface temperature, and wind speed and direction at 1-min intervals. Underway shipboard measurements were made throughout the work to document the horizontal velocity structure along the cruise tracks using a 150-kHz hull-mounted acoustic Doppler current profiler (ADCP) manufactured by RD Instruments. The ADCP was mounted at a depth of 5 m below the sea surface. Underway chemical measurements in water and air included salinity, pCO2 (PU and SIO), pN2O (SIO), and CH4 (SIO). Two different systems were used for pCO2; the PU group used a rotating disk equilibrator and infrared detector, while the Scripps group used a shower type equilibrator and gas chromatograph for the detection of CO2. The pCO2 measurements, including a comparison of the shower and disk equilibrator results, were described by Sabine and Key (1998). A thermosalinograph (manufactured at FSI) was mounted on the bow approximately 3 m below the surface for underway salinity, which was calibrated against surface CTD and bottle salinity values after the cruise (Sabine and Key 1998). The CFC groups periodically analyzed air for CFCs using sampling lines from the bow and stern of the ship. 3.2. Total Carbon Dioxide Measurements TCO2 was determined on 18,963 samples using two automated single-operator multiparameter metabolic analyzers (SOMMA) with coulometric detection of the CO2 extracted from acidified samples. A description of the SOMMA-coulometry system and its calibration can be found in Johnson et al. 1987; Johnson and Wallace 1992; and Johnson et al. 1993. A schematic diagram of the SOMMA analytical sequence and a complete description of the sampling and analytical methods used for discrete TCO2 on the Indian Ocean WOCE sections appear in Appendix B (Johnson et al. 1998). Further details concerning the coulometric titration can be found in Huffman (1977) and Johnson, King, and Sieburth (1985). The measurements for the Indian Ocean Survey were made on two systems provided by BNL (S/Ns 004 and 006) and a backup by WHOI (S/N 023). TCO2 samples were collected from approximately every other station [~ 60 nm intervals, 50% of the stations (Fig. 2)] in 300-mL glass biological oxygen demand (BOD) bottles. They were immediately poisoned with 200 µL of a 50% saturated solution of HgCl2, thermally equilibrated at 20°C for at least 1 h, and analyzed within 24 h of collection (DOE Handbook of Methods 1994). Certified reference material (CRM) samples were routinely analyzed, usually at the beginning and end of the coulometer cell lifetime, according to DOE (1994). As an additional check of internal consistency, duplicate samples were usually collected on each cast at the surface and from the bottom waters. These duplicates were analyzed on the same system within the run of cast samples from which they originated, but the analyses were separated in time usually by ~3 h. Periodically, replicate samples were also drawn for shipboard analysis at sea using coulometry and for later analysis on shore at SIO by manometry. The latter samples, typically designated as the "Keeling samples," consisted of two 500-mL replicate samples collected at two depths (four samples total per station). These were analyzed only if both replicates survived the storage and the return journey to SIO. Seawater introduced from an automated "to-deliver" (TD) pipette into a stripping chamber was acidified, and the resultant CO2 from continuous gas extraction was dried and coulometrically titrated on a model 5011 UIC coulometer. The coulometer was adjusted to give a maximum titration current of 50 mA, and it was run in the counts mode [the number of pulses or counts generated by the coulometer's voltage-to-frequency converter (VFC)] during the time the titration was displayed and acquired by the computer. In the coulometer cell, the acid (hydroxyethylcarbamic acid) formed from the reaction of CO2 and ethanolamine was titrated coulometrically (electrolytic generation of OH-) with photometric endpoint detection. The product of the time and the current passed through the cell during the titration was related by Faraday's constant to the number of moles of OH- generated and thus to the moles of CO2 that reacted with ethanolamine to form the acid. The age of each titration cell was logged from its birth (time that electrical current was applied to the cell) until its death (time when the current was turned off). The age was measured from birth (chronological age) and in mass of carbon (mgC) titrated since birth (carbon age). The systems were controlled with PCs equipped with RS232 serial ports for the coulometer and the barometer, a 24-line digital input/output (I/O) card for the solid state relays and valves, and an analog-to-digital (A/D) card for the temperature, conductivity, and pressure sensors. These sensors monitored the temperature of the sample pipette, gas sample loops, and, in some cases, the coulometer cell. The controlling software was written in GWBASIC Version 3.20 (Microsoft Corp., Redmond, Wash.), and the instruments were driven from an options menu appearing on the PC monitor. The TD volume (Vcal) of the sample pipettes was determined gravimetrically prior to the cruise and periodically during the cruise by collecting aliquots of deionized water dispensed from the pipette into pre-weighed serum bottles which were sealed and re-weighed on shore. The apparent weight of water collected (Wair), corrected to the mass in vacuo (Mvac), was divided by the density of the calibration fluid at the calibration temperature to give Vcal. The sample volume (Vt) at the pipette temperature was calculated from the expression V(t) = V(cal) [1 + a(v) (t - t(cal))] , where av is the coefficient of volumetric expansion for Pyrex-type glass (1 X 10(^-5)/°C), and t is the temperature of the pipette at the time of a measurement. Vcal for the Indian Ocean CO2 survey cruises and a chronology of the pipette volume determinations appear in Appendix B. The coulometers were electronically calibrated at BNL prior to the cruises and recalibrated periodically during the cruises (Sections I8SI9S and I5WI4) to check the factory calibration as described in Johnson et al. (1993) and DOE (1994). The results for the electronic intercepts (Intec) and slopes (Slopeec) are given in Appendix B. For all titrations, the micromoles of carbon titrated (M) was M = [Counts/4824.45 - (Blank x T(t)) - (Int(ec) x T(i))]/Slope(ec) , where 4824.45 (counts/µmol) was the scaling factor obtained from the factory calibration, T(t) was the length of the titration in minutes, Blank is the system blank in µmol/min, and T(i) the time of continuous current flow in minutes. The SOMMA-coulometry systems were calibrated daily with pure CO2 (calibration gas) by titrating the mass of CO2 contained in two stainless steel gas sample loops of known volume and by analyzing CRM samples supplied by Dr. Andrew Dickson of the SIO. The ratio of the calculated (known) mass of CO2 contained in the gas sample loops to the mass determined coulometrically was the CALFAC (~1.004). A complete history of the calibration results appears in Appendix B. For water and CRM samples, TCO2 concentration in µmol/kg was TCO2 = M x CALFAC x [1 / (V(t) x ñ)] x d(Hg) , where p is the density of seawater in g/mL at the analytical t and S calculated from the equation of state given by Millero and Poisson (1981), and d(Hg) is the correction for sample dilution with bichloride solution (for the cruises d(Hg) = 1.000666). System 006 was equipped with a conductance cell (Model SBE-4, Sea-Bird Electronics, Bellevue, Wash.) for the determination of salinity as described by Johnson et al. (1993). Whenever possible, SOMMA and CTD salinities were compared to identify mis-trips or other anomalies, but the bottle salinities (furnished by the chief scientist) have been used to calculate p throughout. Three CRM batches were used for the Indian Ocean Survey. The certified TCO2 concentrations were determined by vacuum-extraction/manometry in the laboratory of C.D. Keeling at SIO and are given in Table 8. TABLE 8: Certified salinity, TALK, and TCO2 for CRM supplied for Indian Ocean CO2 survey _________________________________________________ Batch Salinity TCO2 (µmol/kg) TALK (µmol/kg) ----- -------- -------------- -------------- 23 33.483 1993.10 2212.70 26 33.258 1978.34 2176.60 27 33.209 1988.10 2214.90 _________________________________________________ Optimal cell and platinum electrode configurations, according to criteria given in Appendix B, were selected on the first section (I8S) and were used on all subsequent cruises. The quality control-quality assurance (QC-QA) of the coulometric TCO2 determina- tions was assessed from analyses of 983 CRM samples during the nine Indian Ocean CO2 survey cruises. For both coulometric titration systems (004 and 006) the average TCO2 (measurement minus CRM value) for the whole survey was 0.86 µmol/kg and the standard deviation was ±1.21 µmol/kg. A cruise-by-cruise breakdown of the accuracy and precision of the CRM analyses is given in Appendix B. The small mean difference between the analyzed and certified TCO2 and the very high precision (1.21 µmol/kg) of the differences indicates that the two systems gave very accurate and virtually identical results over the entire survey (see also Fig. 6 in Appendix B). The second phase of the QC-QA procedure was an assessment of sample precision, which is presented in Table 9. The sample precision was determined from duplicate samples analyzed on each system during sections I8SI9S at the beginning of the survey and I4I5W about half way through the survey. The pooled standard deviation (Sp2), shown in Table 9, is the square root of the pooled variance according to Youden (1951) where K is the number of samples with one replicate analyzed on each system, n is the total number of replicates analyzed from K samples, and n - K is the degree of freedom (d.f.) for the calculation. Precision was calculated this way because TCO2 was analyzed on two different systems, and an estimate of sample precision independent of the analytical system was required. Hence Sp2 is the most conservative estimate of precision and includes all sources of random and systematic error (bias). Bias between systems would increase the imprecision of the measurements, but the excellent agreement between the Sp2 values for natural seawater samples (Table 9) and the high precision of the CRM differences confirms the virtually uniform response, accuracy, and high precision of both systems during the survey. This finding confirms that the precision of the TCO2 analyses during the Indian Ocean CO2 survey was ±1.20 µmol/kg. TABLE 9: Precision of discrete TCO2 analyses during Indian Ocean CO2 survey _____________________________ Section Sp2 (K, n, d.f) ------- ------------------ I8SI9S 1.26 (15, 30, 15) I4I5W 0.91 (21, 42, 21) CRM 1.21 _____________________________ The next phase of the QC-QA procedure was the comparison of replicate samples analyzed at sea and in the shore-based laboratory. Samples from every cruise were analyzed at sea by continuous gas extraction/coulometry, and later, after storage, duplicate samples were analyzed on shore by vacuum extraction/manome- try. The results of the analyses are summarized in Table 10. TABLE 10: Mean Difference [TCO2(S-SIO)] and standard deviation of the dif- ferences [S.D.(S-SIO)] between at-sea TCO2 by coulometry and on- shore TCO2 by manometry on aliquots of the same sample from Indian Ocean CO2 survey, and the mean replicate precision [S.D.(SIO)] of the manometric analyses __________________________________________________________________ Section Pairs Analyzed TCO2(S-SIO) S.D.(S-SIO) S.D.(SIO) (a) (n) (µmol/kg) (µmol/kg) (µmol/kg) ------- -------------- ----------- ----------- ------------- I8SI9S 23 -4.14 1.80 0.82 I9N 24 -1.96 1.67 0.80 I8NI5E 17 -4.80 2.87 1.31 I3 29 -3.29 1.26 0.82 I4I5W 16 -2.95 1.40 1.30 I7N 13 -5.37 1.92 1.40 I1 26 -5.59 1.38 1.05 I10 8 -4.94 1.52 1.28 I2 10 -4.42 1.50 0.83 n 166 9 9 9 ---------------------------------------------------------------- Mean -4.16 1.70 1.07 S.D. 1.21 0.49 0.25 __________________________________________________________________ (a) Each on-shore TCO2 by manometry is always the mean of two analyses (see text). In general, the reproducibility and the uniformity of the data as a whole, and specifically, the high precision of the manometric analyses shown in Table 10, indicate that the collection and return of the "Keeling samples" was successfully performed by each of the measurement groups. Poor sampling or storage techniques would probably have been manifested in a much higher imprecision for the on-shore replicate analyses and in the differences between the at-sea and on-shore analyses. However, the negative mean difference (4.16 ± 1.21, n = 9) for the Indian Ocean sections was greater than the mean difference for WOCE sections in other oceans (-1.36 ± 1.37 µmol/kg, n = 22). The accuracy of the CRM analyses, the tendency for the coulometric analyses to give slightly lower results, and the reproducibility of the at-sea and on-shore differences are similar everywhere, but the magnitude of the Indian Ocean difference is clearly the largest observed to date. Even if the consistent and slightly negative difference for the CRM is taken into account (-0.86 µmol/kg), the at- sea coulometric measurements are approximately 2 µmol/kg lower than the manometric method. A suite of samples from the 1997 North Atlantic sections remains to be analyzed. Until these analyses are completed and a thorough statistical evaluation of the entire CO2 survey data set is made, the explanation of the at-sea and on-shore differences, including those found for the Indian Ocean, is not possible. An additional step in the QA-QC was also undertaken. Inspection of Fig. 1 shows points where the cruise tracks cross or nearly cross. The agreement between TCO2 measurements made at these crossover locations (± 100 km) on different cruises was examined by assuming that the temporal and spatial variations in deep-ocean TCO2 are small relative to the measurement accuracy and precision. Hence, deep ocean waters should have the same TCO2 at different times in the absence of internal vertical motion, and because deep ocean motion probably occurs along constant density surfaces (isopycnals), the comparisons of TCO2 measurements were made with reference to density and not depth. Appendixes B and D (Johnson at al. 1998 and Sabine et al. 1999) give a complete description of the statistical procedures used to make the crossover comparisons. Briefly, crossover points were selected for comparison of water samples collected below 2500 m. A smooth curve was fit through the TCO2 data as a function of the density anomaly referenced to 3000 dbar (sigma3) using Cleveland's LOESS smoother (Cleveland and Devlin 1988). A separate fit was performed for the data collected at each of the two intersecting crossover points, but the same tension parameter was used for all of the crossover points so that the smoothing function was consistently applied to all crossover locations. The difference between the two smoothed curves was evaluated at 50 evenly spaced points covering the density range where the two data sets overlapped. A mean and standard deviation for the 50 comparisons was calculated for each crossover point. For TCO2, differences never exceeded 3 µmol/kg, and the overall mean and standard deviation of the differences was -0.78 ± 1.74 µmol/kg. The latter differences were consistent with the overall precision of the CRM analyses (± 1.2 µmol/kg). Tables 8 10 show an internally consistent TCO2 data set for the Indian Ocean with excellent accuracy with respect to the CRM certified values, consistently good precision, no analytical bias between the coulometric titration systems, and crossover agreement to within the precision of the method. However, the agreement between the at-sea and on-shore analyses is not as good as for earlier WOCE sections from other oceans (i.e., the Pacific and the South Atlantic). Based on the accuracy of the CRM analyses and the high precision of the sample analyses, the TCO2 data were not corrected in any way and were deemed to meet survey criteria for accuracy and precision. 3.3. Total Alkalinity Measurements Total alkalinity was measured on 18,928 samples using two closed-cell automated potentiometric titration systems (hereafter designated as MATS) developed at the University of Miami. The MATS are described by Millero et al. (1993) and by Millero et al. (1998). The latter reprinted in Appendix C of this document, completely describes the Indian Ocean Survey TALK measurements and results. Briefly, the MATS consisted of three parts: a water-jacketed, fixed-volume (about 200 mL determined to ± 0.05 mL) closed Plexiglass sample cell, a Metrohm model 665 Dosimat titrator, and a pH meter (Orion, Model 720A), the last two controlled by a PC. The titration cell was similar to those used by Bradshaw and Brewer (1988), but had a greater volume to improve the precision of the measurements. The cell was equipped with flush-mounted fill and drain valves to increase the reproducibility of the cell volume. The cell, titrant burette, and sample container were held at a temperature of 25 ± 0.01°C using a constant temperature bath (e.g., Neslab, Model RTE 221). A Lab Windows C program was used to run the titrators, record the volume of titrant added, and record the measured electromagnetic fields (emf) of the electrodes through RS232 serial interfaces. Two electrodes were used in each cell: a ROSS glass pH electrode (Orion, Model 810100) and a double-junction Ag/AgCl reference electrode (Orion, Model 900200). The specific electrodes used during the Indian Ocean survey were selected after careful screening for non- Nernstian behavior. Only those electrodes which gave TCO2 results in good agreement with TCO2, as determined coulometrically, were used (Sect. 3.2). Seawater samples were titrated by adding increments of HCl until the carbonic acid endpoint of the titration was exceeded. During a titration, the emf readings were monitored until they were stable (± 0.09 mV). Sufficient volume of acid was added to increase the emf by preassigned increment (~13 mV) in order to give an even distribution of data points over the course of a full titration, which consists of 25 data points. A single titration takes about 20 min. A FORTRAN computer program based on those developed by Dickson (1981) and by Johansson and Wedborg (1982) was used to calculate the carbonate parameters. The pH and pK of the acids used in the program are on the seawater scale, and the dissociation constants for carbonic acid were taken from Dickson and Millero (1987). For further details see Appendix C and DOE (1994). The titrant (acid) used throughout the cruises was prepared prior to the cruise, standardized, and stored in 500-mL borosilicate glass bottles for use in the field. The 0.25-M HCl acid solution was prepared by dilution of 1-M HCl in 0.45-M NaCl to yield a solution with total ionic strength similar to that of seawater of salinity 35.0 (I = 0.7 M). The acid was standardized by coulometry (Taylor and Smith 1959; Marinenko and Taylor 1968), and was also checked by independent titration in A. Dickson's laboratory at SIO. The independent determinations agreed to ± 0.0001 M, which corresponds to an uncertainty in TALK of ~ 1 µmol/kg. The Dosimat titrator burettes were calibrated with Milli-Q water at 25°C to ± 0.0005 mL. While CRM samples were available to the TCO2 analysts from the beginning of the measurement program in 1990, the Indian Ocean cruises were the first to have a certified alkalinity standard as well. Hence, the accuracy of the method was checked in the laboratory by analyzing CRM samples from batches 23, 24, 26, 27, 29, and 30 and comparing the analyzed values with the certified TALK determined by A. Dickson at SIO (in the same manner as for TCO2). These results are summarized in Table 11 (see also Appendix C). The mean difference between the MATS measurements in the laboratory and the certified TALK values was -0.8 µmol/kg for CRM samples with a concentration range approximately one-half as large as the range of a typical seawater profile. The excellent agreement indicated that the CRM concept for alkalinity was valid and that the methodology for TALK was ready for the Indian Ocean survey. The results for the at-sea measurements of the CRM samples have been extracted from Table 2 of Appendix C, summarized, and are given in Table 12. TABLE 11: Mean analytical difference (TALK) between analyzed and certified TALK for CRM used during Indian Ocean CO2 survey ____________________________________________________________________ Batch Salinity Certified values MATS mean TALK delta TALK TCO2 TALK (µmol/kg) (MATS - CRM) (µmol/kg) (µmol/kg) ----- -------- --------- --------- -------------- ------------ 23 33.483 1993.10 2212.7 2213.7 1.0 24 33.264 1987.53 2215.5 2215.8 0.3 26 33.258 1978.34 2176.6 2175.1 -1.5 27 33.209 1988.10 2214.9 2214.3 -0.6 29 33.701 1902.33 2184.8 2182.3 -2.5 30 33.420 1988.78 2201.9 2200.5 -1.4 Range 0.492 90.77 38 40.7 3.5 Mean -0.8 ____________________________________________________________________ The analytical differences are for the most part within the precision of the measurements (~ 2-5 µmol/kg) except for the I7N Section. The larger at-sea differences were attributed to operator error or procedures and to uncertainties in the volume of cells, especially after repairs due to leakage, breakage, or repositioning the electrodes after changing the inner filling solutions. Variations between different MATS systems used on a single cruise were corrected using the adjustments required to reproduce the values assigned for the CRM (see Table 11). The at-sea sample titrations were corrected using the results of the at-sea CRM analyses. For TALK, the calibration factor (CF) used to correct the at sea measurements was CF = TALK (meas., CRM) - CRM (certified value), and the corrected TALK (TALKc) was (TALKc) = TALK (meas., Spl) x [ CRM / (CRM + CF)], where CRM was the certified TALK and Spl was the measured sample TALK. The overall precision of TALK determinations during the Indian Ocean survey was ± 4.2 µmol/kg. The precision of the potentiometric pH and TCO2 measurements are given in Table 3 of Appendix C. TABLE 12: Mean analytical difference (TALK) between analyzed and certified TALK for each section during Indian Ocean CO2 survey _____________________________________________________________ Batch Section Certified MATS mean S.D. (n) ∆ TALK TALK TALK (µmol/kg) (MATS-CRM) (µmol/kg) (µmol/kg) (µmol/kg) ----- ------- --------- --------- --------- ---------- 23 I8SI9S 2212.7 2221.5 5.1 (49) 8.8 23 I9N 2212.7 2216.2 3.3 (138) 3.5 23 I8NI5E 2212.7 2211.6 4.9 (80) -1.1 23 I3 2212.7 2215.4 1.4 (65) 2.7 26 I3 2176.6 2178.0 1.2 (30) 1.4 26 I5WI4 2176.6 2182.6 3.8 (79) 6.0 26 I7N 2176.6 2184.0 5.7 (59) 7.4 27 I7N 2214.9 2221.5 3.1 (8) 6.6 23 I7N 2212.7 2222.4 7.4 (10) 9.7 27 I1 2214.9 2219.4 3.9 (244) 4.5 27 I10 2214.9 2212.9 4.0 (62) -2.0 27 I2 2214.9 2219.4 4.5 (67) 4.5 n 891 12 _____________________________________________________________ TALK was also checked at the crossover locations of two cruises in the same way as TCO2. The agreement between the corrected TALK measurements made at the crossover locations (± 100 km) on different cruises was examined by assuming that the temporal and spatial variations of the deep-ocean TALK were small relative to measurement accuracy and precision. Hence, deep ocean waters should have the same TALK at different times in the absence of internal vertical motion, and because deep ocean motion probably occurs along constant-density surfaces (isopycnals), the comparisons of TALK measurements were made with reference to density and not depth. Appendixes C and D give a description of the statistical procedures used to make the crossover comparisons. For water samples collected below 2500 m, a smooth curve was fit through the TALK data as a function of the density anomaly referenced to 3000 dbar (sigma3) using Cleveland's LOESS smoother (Cleveland and Devlin 1988). A separate fit was performed on the data collected at each of the two intersecting crossover points, with the same tension parameter being used for all of the crossovers so that the smoothing function was consistently applied. The difference between the two smoothed curves was evaluated at 50 evenly-spaced points covering the density range where the two data sets overlapped. Mean and standard deviations for the differences at the 50 points were calculated for each crossover point. For TALK, differences never exceeded 6 µmol/kg, and the overall mean and standard deviation of the differences was 2.1 ± 2.1 µmol/kg. The latter were consistent with the overall precision of the CRM analyses (± 4 µmol/kg). Table 13 is a final summation of the inorganic carbon analytical work completed during the Indian Ocean CO2 survey from 1994 to 1996. TABLE 13: Final count of carbonate system parameter (CSP) analyses during Indian Ocean CO2 survey _______________________________________ No. of CSP determinations Parameters Discrete CRM Total ---------- -------- ----- ------ TCO2 18,963 983 19,946 TALK 18,928 949 19,877 Total 37,891 1,932 39,823 ______________________________________ 3.4. Carbon Data Synthesis and Analysis In accordance with one of the stated goals of the program, an evaluation of the data set with respect to estimated anthropogenic CO2 distributions in the Indian Ocean has been completed and published by Sabine et al. (1999) (see Appendix D). The document is appended to this report as Appendix D. Additional crossover comparisons of the survey data with data gathered in the 1980s and in 1993 by French scientists are included. Briefly, the sequestering of anthropogenic CO2 has been estimated by comparing the Indian Ocean survey results with the Indian Ocean GEOSECS expedition data from 1977 to 1978. Although CRM samples were not available for evaluating the earlier data, statistical methods were used to fit these data and correct for calibration offsets so that they could be compared with the current survey data. The data analysis was complicated by regions of pronounced denitrification (Arabian basin) and other regional variations that had to be considered and quantified. In summary, the estimate of the anthropogenic inventory was relatively small in the Indian and Southern Oceans, with anthropogenic carbon uptake lower by a factor of 2 compared to that of the Atlantic Ocean. Importantly, discrepancies between model and data-based estimates were found especially for the Southern Ocean where carbon uptake appears to have been traditionally overestimated by the extant circulation models. (See Appendix D for further details.) The initial data synthesis work indicates that the survey data will provide an important baseline with respect to future studies and that the spatial distribution of anthropogenic carbon can be an important tool for understanding model-based carbon uptake estimates and the response of models to atmospheric increases in CO2. 3.5. Radiocarbon Measurements Full information on the radiocarbon measurement method, instrumentation, and results can be found in Appendix E of this document. 4. DATA CHECKS AND PROCESSING PERFORMED BY CDIAC An important part of the numeric data packaging process at the Carbon Dioxide Information Analysis Center (CDIAC) involves the quality assurance (QA) of data before distribution. Data received at CDIAC are rarely in a condition that would permit immediate distribution, regardless of the source. To guarantee data of the highest possible quality, CDIAC conducts extensive QA reviews that involve examining the data for completeness, reasonableness, and accuracy. The QA process is a critical component in the value-added concept of supplying accurate, usable data for researchers. The following information summarizes the data processing and QA checks performed by CDIAC on the data obtained during the R/V Knorr cruise along WOCE Sections I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, I10, and I2 in the Indian Ocean. 1. The final carbon-related data were provided to CDIAC by the ocean carbon measurement PIs listed in Table 5. The final hydrographic and chemical measurements and the station information files were provided by the WOCE Hydrographic Program Office (WHPO) after quality evaluation. A FORTRAN 90 retrieval code was written and used to merge and reformat all data files. 2. Every measured parameter for each station was plotted vs depth (pressure) to identify questionable outliers using the Ocean Data View (ODV) software (Schlitzer 2001) Station Mode (Fig. 3). 3. The section plots for every parameter were generated using the ODV's Section Mode in order to map a general distribution of each property along all Indian Ocean sections (Fig. 4). 4. To identify "noisy" data and possible systematic, methodological errors, property-property plots for all parameters were generated (Fig. 5), carefully examined, and compared with plots from previous expeditions in the Indian Ocean. 5. All variables were checked for values exceeding physical limits, such as sampling depth values that are greater than the given bottom depths. 6. Dates, times, and coordinates were checked for bogus values (e.g., values of MONTH < 1 or > 12; DAY < 1 or > 31; YEAR < 1994 or > 1996; TIME < 0000 or > 2400; LATITUDE < 70.000 or > 60.000; LONGITUDE < 19.000 or > 119.000. 7. Station locations (latitudes and longitudes) and sampling times were examined for consistency with maps and cruise information supplied by PIs. 8. 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Journal of Research of the National Bureau of Standards 63A:153-9. UNESCO. 1981. Background papers and supporting data on the practical salinity scale, 1978. UNESCO Technical Papers in Marine Science, No. 37: p. 144. Wallace, D.W.R. 2002. Storage and transport of excess CO2 in the oceans: The JGOFS/WOCE Global CO2 survey. In J. Church, G. Siedler, and J. Gould (eds.). Ocean Circulation and Climate, Academic Press, (in press). Youden, W.J. 1951. Statistical Methods for Chemists. Wiley, New York. List of CO2 measurement group members participating in the Indian Ocean CO2 Survey aboard the R/V Knorr in 1994 1996 (CO2 group leaders for each section are given in Table 4 in the text) ________________________________________________________ Section Name Sponsoring Affiliation institute ------- -------------------- ---------- ----------- I8SI9S Haynes, Charlotte H BNL WDNR Haynes, Elizabeth M BNL RU Wysor, Brian S. BNL SHC I9N Dorety, Art PU PU Kozyr, Alex PU ORNL/CDIAC Suntharalingam, Parv PU PU I8NI5E Parks, Justine UH SIO Popp, Brian UH UH Schottle, R. UH UH I3 Aicher, Jennifer RSMAS RSMAS Edwards, Christopher RSMAS RSMAS Krenisky, Joann RSMAS RSMAS I4I5W Lewis, Ernie BNL BNL Pikanowski, Linda BNL SHML Zotz, Michelle BNL BNL I7N Adams, Angela UH UH Angeley, Kelly UH Phillips, Jennifer UH UHH I1 Amaoka, Toshitaka WHOI GSEESHU Okuda, Kozo WHOI GSEESHU Ording, Philip WHOI WHOI I10 Boehme, Sue PU RU Markham, Marion PU PU Mcdonald, Gerard PU PU I2 Admas, Angela UH UH Cipolla, Cathy UH GSOURI Phillips, Jennifer UH UHH ________________________________________________________ Participating institutions: BNL Brookhaven National Laboratory ORNL/CDIAC Oak Ridge National Laboratory/Carbon Dioxide Information Analysis Center GSEESHU Graduate School of Environmental and Earth Science, Hokkaido University GSOURI Graduate School of Oceanography, University of Rhode Island PU Princeton University RSMAS Rosenstiel School of Marine and Atmospheric Science, University of Miami RU Rutgers University SHC South Hampton College SHML Sandy Hook Marine Laboratory SIO Scripps Institution of Oceanography UH University of Hawaii, Honolulu UHH University of Hawaii at Hilo WDNR Wisconsin Department of Natural Resources WHOI Woods Hole Oceanographic Institution APPENDIX B: REPRINT OF PERTINENT LITERATURE Johnson, K.M. , A.G. Dickson, G. Eischeid, C. Goyet, P. Guenther, R.M. Key, F.J. Millero, D. Purkerson, C.L. Sabine, R.G. Schottle, D.W.R. Wallace, R.J. Wilke and C.D. Winn, Coulometric total carbon dioxide analysis for marine studies: assessment of the quality of total inorganic carbon measurements made during the US Indian Ocean CO2 Survey 1994-1996, Marine Chemistry 63:21-37. Marine Chemistry 63(1998) 21-37 COULOMETRIC TOTAL CARBON DIOXIDE ANALYSIS FOR MARINE STUDIES: ASSESSMENT OF THE QUALITY OF TOTAL INORGANIC CARBON MEASUREMENTS MADE DURING THE US INDIAN OCEAN CO2 SURVEY 1994-1996 Kenneth M. Johnson(a)*, Andrew G. Dickson(b), Greg Eischeid(c), Catherine Goyet(c), Peter Guentherb(b), Robert M. Key(d), Frank J. Millero(e), David Purkerson(e), Christopher L. Sabine(d), Rolf G. Schottle(f), Douglas W. R. Wallace(a), Richard J. Wilke(a) and Christopher D. Winn(f) (a) Department of Applied Science, Brookhaven National Laboratory, Upton, NY 11973, USA (b) Scripps Institution of Oceanography, University of California, San Diego, La Jolla San Diego, CA 92093, USA (c) Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA (d) Geology Department, Princeton University, Princeton, NJ 08544, USA (e) Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33149, USA (f) Department of Oceanography, University of Hawaii, Honolulu, HI 96822, USA *Corresponding author. Tel.: +1-516-344-5668; Fax: +1-516-344-3246 Received 8 January 1998; accepted 6 May 1998. Available online 8 December 1998. 0304-4203/98/$ - see front matter (c) 1998 Elsevier Science B.V. All rights reserved. PII: S0304-42039800048-6 ABSTRACT Two single-operator multiparameter metabolic analyzers (SOMMA)-coulometry systems (I and II) for total carbon dioxide (TCO2) were placed on board the R/V Knorr for the US component of the Indian Ocean CO2 Survey in conjunction with the World Ocean Circulation Experiment-WOCE Hydrographic Program (WHP). The systems were used by six different measurement groups on 10 WHP Cruises beginning in December 1994 and ending in January 1996. A total of 18,828 individual samples were analyzed for TCO2 during the survey. This paper assesses the analytical quality of these data and the effect of several key factors on instrument performance. Data quality is assessed from the accuracy and precision of certified reference material (CRM) analyses from three different CRM batches. The precision of the method was 1.2 µmol/kg. The mean and standard deviation of the differences between the known TCO2 for the CRM (certified value) and the CRM TCO2 determined by SOMMA-coulometry were -0.91±0.58 (n=470) and -1.01±0.44 (n=513) µmol/kg for systems I and II, respectively, representing an accuracy of 0.05% for both systems. Measurements of TCO2 made on 12 crossover stations during the survey agreed to within 3 µmol/kg with an overall mean and standard deviation of the differences of -0.78±1.74 µmol/kg (n=600). The crossover results are therefore consistent with the precision of the CRM analyses. After 14 months of nearly continuous use, the accurate and the virtually identical performance statistics for the two systems indicate that the cooperative survey effort was extraordinarily successful and will yield a high quality data set capable of fulfilling the objectives of the survey. AUTHOR KEYWORDS: total carbon dioxide (TCO2); single-operator multiparameter metabolic analyzers (SOMMA) coulometry; marine studies INDEX TERMS: reproductive toxicity; boron ARTICLE OUTLINE 1. Introduction 2. Materials and methods 2.1. Preparations 2.2. Selection of cell assemblies 2.3. At-sea operations 2.4. Calculation of results 2.5. Assessment of analytical accuracy 2.6. Data distribution 3. Results 3.1. To-deliver pipette volume 3.2. CRM analyses and system accuracy 3.3. System repeatability and precision during the survey 4. Discussion 5. Crossover analysis 6. Conclusions Acknowledgements References 1. INTRODUCTION Between 1990 and 1997 an international effort was made to determine the global oceanic distribution of inorganic carbon in conjunction with the World Ocean Circulation Experiment (WOCE) Hydrographic Programme (WHP). This effort is referred to as the Global Survey of CO2 in the oceans, and it is an integral part of the Joint Global Ocean Flux Study (JGOFS). The goals of this survey are to: 1. Accurately determine the oceanic distribution of dissolved inorganic carbon, 2. Quantify the uptake of anthropogenic carbon dioxide by the oceans to better predict future atmospheric carbon dioxide levels, 3. Provide a global description of anthropogenic carbon dioxide in the oceans to aid development of a 3-dimensional model of the oceanic carbon cycle, 4. Characterize the transport of carbon dioxide between the ocean and the atmosphere and the large scale (e.g., meridional) transports of carbon dioxide within the ocean. The survey has acquired a global data set of profile measurements of dissolved carbon dioxide parameters on both zonal and meridional oceanographic transects throughout the world's oceans. With reference to program goals, Bates et al. (1996) found that for mixed layer waters the average rate of increase in CO2 concentration due to the uptake of anthropogenic CO2 was 1.7 µmol/kg/yr (<0.1%). This rate of increase establishes a natural target for the accuracy of the TCO2 measurements. The distribution of this 'excess' CO2 signal is not uniform spatially, and it is masked by variability in CO2 concentrations arising from natural biological and physicochemical processes. Hence, the goals of the program imply that measurements must be extremely accurate (0.1% or better) and spatially extensive. A large part of the US contribution to this survey has been conducted by a team of investigators supported by the US Department of Energy (DOE). This team has developed certified reference materials (Dickson, 1990), instrumentation (Johnson and Wallace, 1992), a set of standard operating procedures (DOE, 1994) and, to a large extent, shared a common approach to the measurement program. This paper presents the DOE team effort which sampled the Indian Ocean for inorganic carbon during the course of approximately 1 year. All the measurements were made aboard a single research vessel during sequential cruises which allowed the investigators to share equipment and procedures to an unprecedented extent. This paper concentrates on estimating the accuracy of the shipboard determinations of the total dissolved inorganic carbon concentration of seawater. This parameter was established at the onset of the survey as the primary carbonate system parameter because its concentration should change in response to anthropogenic CO2 uptake and it had the highest potential for measurement accuracy. Our results highlight some factors which affect the accuracy of this measurement. The Indian Ocean Survey aboard the R/V Knorr encompassed the cruise legs shown in Fig. 1 in the sequence given in Table 1. Fig. 1 also gives the location of the crossover points (cruise track intersections) where comparisons of the reproducibility of the TCO2 analyses were made. The six survey groups measured two water column carbonate system parameters, total dissolved carbon dioxide (TCO2) and total alkalinity (TA), and assisted with the operation of an underway pCO2 (surface) system. This paper focuses on TCO2 by coulometry, while the total alkalinity (TA) and partial pressure of CO2 (pCO2) measurements are the subject of companion papers and reports (Millero et al., 1998; Sabine and Key, 1998). Fig. 1. The cruise tracks for the nine legs of the US Indian Ocean WOCE Survey 1994-1996. Crossover points between the various legs are marked with a square and numbered. These intersection points and crossovers are referred to in Table 4. TABLE 1: Approximate dates and ports of call for the 9 legs of the Indian Ocean CO2 Survey, and the measurement groups responsible for the determination of the carbonate system parameters ______________________________________________________________________________ Leg Dates From To Group Duration Start End (days) -------- -------- -------- ---------- ---------- ------------ -------- I8SI9S 12r1r94 1r19r95 Fremantle Fremantle BNL 50 I9N 1r24r95 3r6r95 Fremantle Colombo Princeton U. 42 I8NI5E 3r10r95 4r16r95 Colombo Fremantle U. of Hawaii 38 I3 4r20r95 6r7r95 Fremantle Port Louis U. of Miami 49 I5WI4 6r11r95 7r11r95 Port Louis Port Louis BNL 31 I7N 7r15r95 8r24r95 Port Louis Matrah U. of Hawaii 41 I1 8r29r95 10r18r95 Matrah Singapore WHOI 51 Dry Dock 10r19r95 11r5r95 Singapore 17 I10 11r6r95 11r24r95 Singapore Singapore Princeton U. 19 I2 11r28r95 1r19r96 Singapore Mombasa U. of Hawaii 53 ______________________________________________________________________________ Abbreviations: BNL, Brookhaven National Laboratory; U, University; WHOI, Woods Hole Oceanographic Institution. 2. MATERIALS AND METHODS 2.1. PREPARATIONS The total carbon dioxide concentration (TCO2) was determined using two single- operator multiparameter metabolic analyzers (SOMMA) each connected to a Model 5011 coulometer (UIC, Joliet, IL 60434). Descriptions of the SOMMA-coulometer system and its calibration can be found in the works of Johnson (1995), Johnson and Wallace (1992), and Johnson et al. (1987) and Johnson et al. (1993). A schematic diagram of the SOMMA is shown in Fig. 2, and further details concerning the coulometric titration can be found in the works of Huffman (1977) and Johnson et al. (1985). Briefly, seawater fills an automated to-deliver sample pipette. The contents of the pipette are pneumatically injected into a stripping chamber containing approximately 1.2 cm3 of 8.5% (v/v) phosphoric acid, and the resultant CO2 is extracted, dried, and coulometrically titrated. Calibration is performed by titrating known masses of pure CO2 and checked by analyzing certified reference material (CRM). The coulometers were adjusted to give a maximum titration current of 50 mA, and they were run in the counts mode (the number of pulses or counts generated by the coulometer's voltage to frequency converter during the titration is displayed). In the coulometer cell, the acid (hydroxyethylcarbamic acid) formed from the reaction of CO2 and ethanolamine is titrated coulometrically (electrolytic generation of OH¯) with photometric endpoint detection. The systems were equipped with conductance cells (Model SBE-4, Sea-Bird Electronics, Bellevue, WA) for measuring salinity as described by Johnson et al. (1993). Fig. 2. SOMMA-coulometer system schematic. Carbon dioxide extracted from a water sample (I) or from volume-calibrated gas sample loops filled at a known pressure and temperature is degassed from the stripper (IV), dried (V), and coulometrically titrated (VI). The water sample is pneumatically injected from the pipette (II) into the stripper, and the pure CO2 contained in the gas loops is delivered to the stripper from an 8-port chromatography valve (VII) equipped with pressure and temperature sensors. Salinity is measured using a conductance cell (III) integrated into the SOMMA chassis. The pipette and conductance cell are thermostatted and equipped with temperature sensors. The DOE supported the construction of nine SOMMA-coulometer systems for the US CO2 Survey Measurement Groups in the early 1990's (Johnson and Wallace, 1992), and two of these systems from the DOE instrument pool were set up aboard the R/V Knorr in Fremantle, Australia on November 28, 1994. Before they were shipped to Australia, the temperature sensors were calibrated, the glassware was chemically cleaned and gravimetrically calibrated, the gas sample loop volumes were calibrated according to the procedure of Wilke et al. (1993), the coulometers were electronically calibrated (Johnson et al., 1993; DOE, 1994), and system accuracy was verified with CRM at Brookhaven National Laboratory (BNL). The same two systems (hereafter called I and II) were used by all measuring groups. A backup system (from Woods Hole Oceanographic Institution) was onboard but was not used. Pre-cruise preparations also included a training session for participants at the University of Miami in September 19-23, 1994. Referring to Fig. 2, the analytical gases included UHP nitrogen (99.998%) for carrier and pneumatic gases, compressed air for the headspace gas, and analytical grade CO2 (99.995%) from Scott Speciality Gases (South Plainfield, NJ) for the calibration gas. The survey began with the use of compressed gases, but prior to leg I8N in April 1995, a N2 generator (TOC Model 1500, Peak Scientific, Chicago, IL) was placed into service. The generator provided N2 (99.9995%, hydrocarbons<0.1 ppm, CO2<1.0 ppm) for carrier and pneumatic gases to both systems for the remainder of the survey. Unless otherwise stated, all other reagents remain as described by Johnson et al. (1993). The BNL measurement group supplied 7 side-arm type glass titration cells (UIC, PN 200-034), 7 silver electrodes (PN 101-033), and 5 rubber cell caps (PN 192- 005). A platinum electrode (PN 101-034), temperature sensor (PN LM34CH, National Semiconductor, Santa Clara, CA), and a teflon inlet tube were mounted in each cap. Together, the cell and cap comprise the cell assembly shown in Fig. 3. For this paper, each cell assembly is assigned an 'age' or lifetime which is measured in minutes (chronological age) or by the mass of carbon titrated in mg C (carbon age) from the time when current is first applied to the assembly (cell birth) until the current is turned off (cell death). The software continuously records the chronological and carbon ages. Fig. 3. The titration cell assembly and the cathodic and anodic half reactions for the coulometric titration of the H+ from the acid formed by the reaction of CO2 and ethanolamine. 2.2. SELECTION OF CELL ASSEMBLIES The performance of individual cell assemblies (Fig. 3) varies widely (K.M. Johnson, unpublished data). Unacceptable assemblies exhibit high blanks, prolonged blank determinations (>2 h), reduced accuracy or precision, or become noisy early in their lifetime. Acceptable assemblies stabilize quickly (within 60 min) and function well for periods exceeding 24 h. Cell behavior will be discussed elsewhere, but our experience suggests several factors play a role: quality of the reagents; quality (purity) of the carrier gases; damage to the platinum electrode; and perhaps the porosity of the cell frit. Therefore, a systematic effort was made at the beginning of leg I8SI9S to select satisfactorily performing cell assemblies using pretested reagents and carrier gas sources known to be uncontaminated. During this first leg, the assemblies on hand were evaluated for conformance to the following empirical criteria. (1) Cell assemblies should attain a blank of ≤0.005 µmol C/min within 90 min of cell birth. Satisfactory assemblies usually exhibit a 15-25% decline in the blank with each successive determination. (2) The gas calibration factor, which is the ratio of an accurately known mass of CO2 to the mass of this gas determined coulometrically, should be 1.004±0.0015 (recoveries of 99.6%). (3) Titrations of CO2 extracted from gas sample loops (gas calibration) or pipettes of 20 cm3 (sample analysis) should take 9-12 min. (4) Cell assemblies, which repeatedly exhibit titrations longer than 20 min (no endpoint) before their carbon age reached 30 mg C titrated, were considered defective. An occasional failure to attain an endpoint after the carbon age exceeds 30 mg C was interpreted to mean that the cell frit required cleaning with 6 N HNO3 and retesting. Based on these criteria, three assemblies (2 primary and a third as backup) were found to be acceptable during the first leg, and these assemblies were used throughout the survey (at the midpoint of the survey an additional assembly was placed into service). 2.3. AT-SEA OPERATIONS The following TCO2 sampling and measurement practices were followed throughout the survey. (1) The daily sequence of analytical operations for each system as described in the SOMMA operator's manual (Johnson, 1995) consisted of changing the cells and drying agents, determining the blank, running test seawater samples, calibrating the system using pure CO2 (gas calibration), analyzing samples, and analyzing certified reference material (CRM) at the beginning and end of the cell lifetime. (2) A complete deep vertical profile for TCO2 and TA consisted of 36 samples. A lesser number of samples were drawn at shallower stations. Complete profiles were taken at every other station, and if time permitted, additional truncated profiles (0-1000 m) were taken. TCO2 samples always coincided with 14C samples. Samples were drawn from 10-l Niskin bottles according to DOE (1994). (3) Samples for TCO2 were collected in 300 cm3 BOD-type glass bottles. They were poisoned with a saturated HgCl(2) solution (200-400 µl) upon collection. The appropriate correction factors for dilution were applied by the measurement groups according to DOE (1994). (4) Sample bottles were rinsed and then allowed to overflow by at least 1/2 volume before poisoning. Prior to April 1995, a glass stopper was inserted into the full BOD bottle. After April 1995, a headspace of approximately 4 cm3 was created before poisoning and stoppering. This was done in a reproducible manner by squeezing the filling tube shut before withdrawing it from the bottle. This change was made to ensure that no HgCl(2) was displaced by the stopper, and to allow for water expansion. The gas-liquid phase ratio was approximately 1.3%. A correction (±0.5 µmol/kg) for the reequilibration of the liquid with the gas phase was applied by the measurement groups according to DOE (1994). (5) To estimate sample precision, duplicate samples were normally collected at surface, mid depth, and at the deepest depth. The duplicate analyses were interspersed with the analysis of the other profile samples with a minimum of 2 h and up to 12 h between duplicate analyses. Because the duplicate analyses were separated in time, these data could potentially detect drift (decreased precision) as the cell aged. Every effort was made to run each station profile on a single cell assembly, and to limit the cell lifetime to ≤35 mg C. (6) Although salinity was determined by the SOMMA-coulometer systems, post- cruise sample density was calculated using bottle salinities supplied by the chief scientists. However, SOMMA-based salinities were often compared to the real-time CTD salinities to spot bottle mistrips during the taking of the vertical profiles. The agreement between SOMMA-based and CTD salinities was ±0.02 or better. (7) To monitor the volume of the SOMMA pipettes, they were periodically filled with deionized water at known temperatures, and their output collected in preweighed serum bottles. The bottles were sealed immediately and stored until they were reweighed at BNL on a model R300S (Sartorius, Göttingen, Germany) balance. The mass of water corrected for buoyancy was used to calculate the to-deliver pipette volume (V(cal), Eq. 3) according to DOE (1994). (8) After use, cells were cleaned with deionized water followed by an acetone rinse of the glass frit. Before reuse, they were dried at 55°C for at least 12 h. Cell caps and the platinum electrodes were thoroughly washed with deionized water and dried at 55°C for at least 6 h before reuse. (9) Duplicate samples from approximately 3000 m and 20 m were regularly collected for shore-based reference analyses of TCO2 by vacuum extraction/manometry by C.D. Keeling at the Scripps Institution of Oceanography (SIO). Between 2 and 5% of the samples analyzed at sea will be analyzed at SIO and reported elsewhere. 2.4. CALCULATION OF RESULTS For the coulometric determination, the mass of carbon titrated from CO2 extracted from the gas sample loops or a water sample in µmol of carbon is given by M according to: M=[Counts/4824.45-(Blank x t(t))-(Int(ec) x t(i))]/Slope(ec), (1) where Counts is the coulometer display, i.e., the number of pulses accumulated by the coulometer's voltage to frequency circuit (VFC); 4824.45 (counts/µmol) is a scaling factor derived from the factory calibration of the VFC and the value of the Faraday (96,485.309 C/mol); Blank is the system blank in µmol/min; t(t) is the length of the titration in minutes; Int(ec) is the intercept from the electronic calibration of the coulometer; ti is the duration (min) of continuous current flow, and Slope(ec) is the slope from electronic calibration (Johnson et al., 1993; DOE, 1994). Electronic calibration serves as a check of the factory calibration. If the coulometer was perfectly calibrated, the slope and intercept would be 1 and 0, respectively. Typically, minor deviations from the theoretical slope (0.998-0.999) and intercept (0.001-0.01) are observed. The water sample TCO2 concentration in µmol/kg is calculated from: TCO2 = M x Calibration Factor x 1/(V(t)p))D+∆TCO(2), (2) where VT is the sample volume (to-deliver volume of the SOMMA pipette) calculated from: V(T)=V(cal)[1+a(v)(T-T(cal)], (3) and T is the analytical temperature; V(cal) is the calibrated volume of the pipette at the calibration temperature, T(cal); av is the coefficient of volumetric expansion for Pyrex glass (1.0 x 10(^-5)/deg). In Eq. 2, Calibration Factor is the gas calibration factor (see Eq. 4); p is the density of seawater from the seawater equation of state (Millero and Poisson, 1981) at the sample salinity and T; D is the correction due to dilution of the sample with HgCl(2) preservative; ∆TCO2 is the correction for the repartitioning of CO2 into the sample headspace according to DOE (1994). Note that correction factors D and ∆TCO2 (Eq. 2) are not incorporated into the SOMMA software and were applied post cruise by the individual measurement groups. The gas calibration factor (Calibration Factor) is the ratio of: M(calc)/M, (4) where M(calc) is the mass of CO2 contained in the gas sample loop calculated according to DOE (1994), and M is the coulometric determination of that same mass from Eq. 1. 2.5. ASSESSMENT OF ANALYTICAL ACCURACY Analytical accuracy was assessed by analyzing certified reference materials (CRMs). The CRMs are filtered seawater poisoned with HgCl(2). They are prepared in 500 cm3 bottles at the Scripps Institution of Oceanography (SIO) according to procedures given by Dickson (1990). The certified TCO2 value is obtained by analyzing a representative number of samples by vacuum extraction/manometry in the laboratory of C.D. Keeling at SIO. For this paper, the term analytical difference refers to the difference between the analyzed (by coulometry) and the certified value of the CRM (by manometry), i.e., at-sea accuracy is estimated from the analyzed TCO2-certified TCO2 differences. 2.6. DATA DISTRIBUTION The complete data set has been submitted to the Carbon Dioxide Information Analysis Center (CDIAC) at the Oak Ridge National Laboratory (ORNL). CDIAC will issue a final data report which will detail the procedures for retrieving the data. The overall accuracy given below is considered final at this time, and the estimated precision is expected to remain unchanged. The CDIAC web address is http://cdiac.esd.ornl.gov. 3. RESULTS During the survey, approximately 18,828 separate samples (not counting dupli- cates) for TCO2, and 983 CRM were analyzed on the two systems (A. Kozyr, personal communication, November 1997). 3.1. TO-DELIVER PIPETTE VOLUME Some 103 gravimetric determinations of the sample pipette volume were made on 28 separate occasions during the survey (14 on each system). Four of the determina- tions were rejected; two because they were exactly 1 cm3 too high with respect to the survey mean (likely due to failure to correctly note the tare weight determined prior to the cruise), and two because they were inexplicably 0.3% lower than the survey mean volumes (probably due to faulty sealing and evapora- tion). There were no results from leg I8N because the gravimetric samples were collected incorrectly. Volume determinations should have been made at the start, middle, and at the end of each leg, or at least at the beginning and end of each leg. However, for a variety of reasons, this was not always the case. In order to consistently assign a pipette volume to each leg, a leg-specific volume (V(cal)) was obtained by averaging the volume determinations made closest to the beginning and end of the leg along with any made during that leg. Table 2 presents the results for V(cal), and the chronological order of the pipette determinations used to calculate V(cal) are plotted in Fig. 4a for system I and Fig. 4b for system II. This averaging increases the number of determinations used to calculate V(cal), and ensures that V(cal) is based on at least two sets of determinations, separated in time, for all legs except the initial leg (I8SI9S) and leg I10 after the pipette was cleaned. Table 2 and Fig. 4a and b show the timing of events which could conceivably have affected pipette volume. For I8SI9S, the pipette volumes were determined in the laboratory prior to the cruise; however, the volume of system I had to be empirically redetermined at- sea because its pipette was broken during transit. This was done as follows: after replacing the pipette, V(cal) was determined by simultaneously analyzing a replicate from a single seawater sample on systems I and II. Because V(cal) was well known for system II, the TCO2 concentration determined on system II was used to calculate the pipette volume of system I by rearranging Eq. 2 to solve for VT and letting VT be equal to V(cal) for the subsequent analyses on system I during leg I8SI9S. As Table 2 shows, numerous volume determinations were made for both systems I and II on succeeding legs. TABLE 2: The leg-specific to-deliver pipette volume (V(cal)) and the calibration temperature (T(cal)) for SOMMA-coulometer systems I and II during the Indian Ocean Survey 1994-1996 ______________________________________________________________________________ Leg n V(cal) S.D. R.S.D. T(cal) Determinations (cm^3) (±cm^3) (%) (C) averaged (legs) ------ -- ------- ------ ------ ----- ----------------- System I I8SI9S 2 21.4609 0.0037 0.02 20.00 see text, 8S9S(e) I9N 9 21.4543 0.0112 0.05 20.97 8S9S(e), 9N(e) Gas generator introduced as CG source I8NI5E 9 21.4443* 0.0021 0.01 20.97 9N(e), 3(m) I3 15 21.4471 0.0042 0.02 20.57 9N(e), 3(m), 4(s) Gas generator output pressure adjusted from 5 to 10 psi I5WI4 10 21.4506* 0.0023 0.01 19.93 5W4(s,e) I7N 8 21.4506 0.0032 0.02 20.36 7N(s,m,e) I1 5 21.4462 0.0074 0.03 20.12 7N(e), 1(e) Pipette dismounted,cleaned,and recalibrated I10 5 21.4460 0.0110 0.05 20.08 10(e) I2 8 21.4482 0.0091 0.04 20.08 10(e), 2(s,e) System II I8SI9S 18 21.6388 0.0068 0.03 20.24 8S9S(s,e) I9N 9 21.6360 0.0163 0.08 20.49 8S9S(e), 9N(e) Gas generator introduced as CG source I8NI5E 8 21.6239 0.0080 0.04 20.56 9N(e), 3(m) I3 14 21.6243 0.0068 0.03 20.31 9N(e), 3(m), 4(s) Gas generator output pressure adjusted from 5 to 10 psi I5WI4 11 21.6293 0.0068 0.03 19.97 5W4(s,e) I7N 8 21.6194* 0.0048 0.02 20.05 7N(s,m,e) I1 4 21.6156 0.0035 0.02 20.00 7N(e), 1(e) Pipette dismounted,cleaned,and recalibrated I10 4 21.6269* 0.0017 0.01 19.95 10(e) I2 9 21.6270 0.0028 0.01 19.94 10(e),2(s,e) ______________________________________________________________________________ The subscripts (s, m, or e) for the pipette volume determinations averaged to calculate V(cal) signify determinations made at the start, middle, or end of a leg, respectively. Values of V(cal) which are significantly different from the V(cal) of the preceding leg are denoted by the asterisk. Fig. 4. The temporal record of the analytical performance of SOMMA-coulometer system I (Fig. 4a) and II (Fig. 4b) during the Indian Ocean Survey 1994-1996. The top section of the three-part graphs shows the leg- specific pipette volumes, V(cal), as horizontal lines corresponding to the duration of the individual legs, and the relative chronological order of the means of the individual pipette determinations from which V(cal) was calculated as open circles placed before, in the middle of, or following the horizontal lines representing V(cal) (see text and Table 2 for details). The middle section depicts the mean gas calibra- tion factors for each leg (horizontal lines), and the bottom section shows the mean analytical differences for the CRM analyses assuming a constant pipette volume (V(cal) for leg I8S) for the duration of the survey (open circles) vs. the leg-specific V(cal) (closed circles). The error bars through the plot symbols represent the S.D. of the determi- nations. Procedural changes (introduction of the gas generator, pressure adjustments, and cleaning) which may have affected pipette volume are indicated by the arrows. For I10, data from the prior leg could not be used to calculate V(cal) because leg I10 took place after the pipettes had been dismounted for cleaning, which may have altered their volumes. On legs I5WI4 and I7N, replicate volume determinations were made at the beginning, middle, and end of the leg by the same measuring group so that V(cal) for these legs do not include results from preceding or succeeding legs. The survey mean pipette volumes and their standard deviations for systems I and II are 21.4502±0.0032 cm3 at 20.25°C (n=43) and 21.6261±0.0028 cm3 at 20.14°C (n=56), respectively. The pooled standard deviation (sp^2) calculated according to Youden (1951) for the 28 sets of gravimetric determinations is ±0.0042 cm3. Individually, sp^2 for system I is ±0.0049 cm3, and for system II sp^2 is ±0.0036 cm3, suggesting a very slightly higher precision for system II. Significant differences at the 95% confidence level in V(cal) for comparisons between each leg with the succeeding leg were determined by two-tailed t-tests according to Taylor (1990), and are denoted by asterisks in Table 2. For the most part, leg to leg differences in V(cal) are not significant (significance in 2 of 9 comparisons for each instrument), but it should be noted that for both systems, the differences between the initial leg (I8SI9S) pipette volumes and all leg-specific volumes after leg I9N are significant. In both systems, the to- deliver pipette volume declines slightly with time. However, the decline is not consistent between instruments. In system I, significant decreases in volume appear earlier in the survey and may be correlated with the switch to the N2 generator and a documented generator outlet pressure adjustment, but this is not the case with system II where dismounting and cleaning of the pipette late in the survey may have had the greatest effect. TABLE 3: A summary of the mean analytical parameters and mean analytical differences for the three batches of CRM analyzed on SOMMA-coulometer systems I and II during the Indian Ocean Survey 1994-1996 _____________________________________________________________________________ Leg Slope Int Cal- CRM Precision, Analytical difference (ec) (ec) factor batch n(±µmol/kg const-vp/corr-vp ------- ------ ------- ------ ----- ---------- --------------------- System I I8SI9S 1.0002 0.0008 1.0043 23 1.15(54) -0.41/-0.41 I9N 1.0007 0.0013 1.0045 23 0.86(71) -0.83/-0.20 I8NI5E 1.0007 0.0013 1.0062 23 1.36(55) -1.71/-0.15 I3 1.0007 0.0013 1.0053 23 0.98(37) -2.33/-1.31 I3 1.0007 0.0013 1.0053 26 0.98(20) -2.77/-1.72 I5WI4 0.9998 -0.0057 1.0041 26 1.31(41) -1.83/-0.88 I7N 0.9998 -0.0057 1.0043 23 1.71(6) -1.66/-0.69 I7N 0.9998 -0.0057 1.0043 26 1.88(55) -1.74/-0.78 I7N 0.9998 -0.0057 1.0043 27 0.88(8) -2.91/-1.95 I1 0.9998 -0.0057 1.0038 27 1.10(64) -2.82/-1.45 I10 0.9998 -0.0057 1.0037 27 0.72(32) -0.58/-0.58 I2 0.9998 -0.0057 1.0040 27 1.11(27) -0.57/-0.77 Mean 1.0045 1.17(470) -1.68/-0.91 S.D.(±) 0.0008 0.35 0.92/ 0.58 System II 1I8SI9S 0.9996 -0.0025 1.0041 23 1.18(104) -0.89/-0.89 I9N 0.9996 -0.0025 1.0039 23 0.90(70) -1.83/-1.57 I8NI5E 0.9996 -0.0025 1.0041 23 1.14(59) -1.73/-0.35 I3 0.9996 -0.0025 1.0045 23 0.85(35) -2.14/-0.62 I3 0.9996 -0.0025 1.0045 26 0.69(13) -2.44/-1.11 I5WI4 0.9998 0.0045 1.0050 26 0.79(41) -2.14/-1.28 I7N 0.9998 0.0045 1.0051 23 0.88(5 ) -3.25/-1.47 I7N 0.9998 0.0045 1.0051 26 0.84(54) -2.09/-0.32 I7N 0.9998 0.0045 1.0051 27 0.77(10) -2.88/-1.10 I1 0.9998 0.0045 1.0041 27 1.11(70) -3.51/-1.38 I10 0.9998 0.0045 1.0038 27 0.65(28) -0.66/-0.66 I2 0.9998 0.0045 1.0035 27 1.11(24) -1.38/-1.39 Mean 1.0042 0.91(513) -2.08/-1.01 S.D.(±) 0.0005 0.18 0.87/ 0.44 _____________________________________________________________________________ For each CRM batch analyze d, precision is given as the standard deviation of the mean of (n) analyses. Abbreviations: ec, electronic calibration; calfactor, gas calibration factor; Int, intercept; const-vp, mean analytical difference calculated using a constant pipette volume; corr-vp, mean analytical difference calculated using the leg-specific V(cal) (Table 2). (a) Gas Generator introduced as CG source. (b) Gas generator output pressure adjusted from 5 to 10 psi. (c) Pipette dismounted, cleaned and recalibrated. 3.2. CRM ANALYSES AND SYSTEM ACCURACY In addition to the leg-specific pipette volumes, Fig. 4a (system I) and Fig. 4b (system II) show the mean analytical differences (analyzed TCO2-certified TCO2) and the mean gas calibration factors for each survey leg. The plots are scaled so that each Y-axis spans a similar range in order that the factors controlling system accuracy can be more readily identified. These data are also tabulated and summarized in Table 3. Table 3 shows that the gravimetric volume determinations (Table 2) have detected real changes in V(cal) during the survey. The mean analytical differences calculated with the corrected pipette volumes (corr-vp, Table 3) are -0.91 and -1.01 µmol/kg for systems I and II, respectively. If the pipette volumes determined at the beginning of the survey (const-vp) were used, the corresponding differences would be -1.61 and -2.08 µmol/kg, showing that the routine determination of pipette volume increased accuracy by a factor of ~2. Fig. 5 is a bar chart of the mean analytical difference (accuracy) for systems I and II as a function of cell carbon age. Both systems behave very similarly with the best precision and accuracy early in the cell lifetime (<10 mg C), increasing differences for cells of intermediate ages (>10 to <30 mg C), and smaller differences for carbon ages exceeding 30 mg C which are not significantly different from those at ages <10 mg C. No corrections based on the analyzed-certified TCO2 differences or cell age have been applied to the CDIAC data set. Fig. 5. A plot showing the distribution of mean analytical differences for CRM analyses vs. coulometer cell age for SOMMA-coulometer systems I (open bars) and II (filled bars) during the Indian Ocean Survey 1994-1996. The error bars represent the 95% confidence interval for the mean differences, and the numbers inside the columns are the number of measurements (n) used to compute the means. 3.3. SYSTEM REPEATABILITY AND PRECISION DURING THE SURVEY For the survey as a whole, the operating conditions and analytical performance of the two SOMMA systems were virtually identical. Survey-wide the mean gas calibration factors of the two systems were nearly identical (1.0045 for system I compared to 1.0042 for II). While both systems yielded slightly negative (~1.0 µmol/kg) mean analytical differences (Table 3), the standard deviation of the analytical differences was slightly better on system II (±0.91 µmol/kg) than system I (1.17 µmol/kg). This is consistent with the gravimetric volume determinations where system II also exhibited a slightly higher precision (sp^2=±0.0036 cm^3 vs. ±0.0049 cm^3 for system I). For the CRM analyses, the precision or pooled standard deviation (sp^2) calculated according to Youden (1951) is 1.19 µmol/kg (df=977). For this calculation, the three batches of CRM analyzed on the two systems are treated as six separate samples with multiple replicates. Because sp^2 includes CRM data measured on both systems on all legs, it applies to both systems on all legs. For water samples, sp^2 was calculated from duplicates analyzed on each system during leg I8SI9S at the start of the survey and leg I5WI4 about half way through the survey. The sp^2 for leg I8SI9S is ±1.26 µmol/kg (df=15), and for leg I5WI4, sp^2 is ±0.91 µmol/kg (df=21). These values are consistent with the precision of the CRM analyses given in Table 3. For the survey, the overall precision of the TCO2 determination is ±1.19 µmol/kg. Fig. 6 is a plot of the analytical differences by system and CRM batch for the entire survey. The differences, calculated using the parameters in Table 3, reiterate the point that there are no significant analytical differences (bias) between systems or between CRM batches. Fig. 6. The analytical differences for the CRM analyses made on SOMMA- coulometer systems I and II during the Indian Ocean Survey 1994-1996 with separate symbols for the results from the two systems and for the three batches of CRM analyzed. The beginning and end of each leg is marked by vertical dashed lines. The respective salinities and certified TCO2 (µmol/kg) for batches 23, 26, and 27 are 33.483 and 1993.10, 33.258 and 1978.34, 33.209 and 1988.10 µmol/kg. 4. DISCUSSION The Indian Ocean CO2 Survey differed from the previous DOE CO2 Survey efforts in that a single ship was used for all legs, and that the measurement groups shared the same analytical equipment. The latter included the use of a single cache of coulometric reagents (two different lot numbers both of which were tested pre- cruise with CRM), invariant sources of analytical gases, use of the same titration cell assemblies, standard sampling procedures, and standardized software. There was a pre-cruise training session, and all of the participants had prior experience with the sampling and measurement techniques (poisoning, reagent concentrations, standard calculations, glassware calibration, etc.) documented in the DOE Handbook of Methods (DOE, 1994). Thus, an extraordinary effort over several years to ensure analytical quality and uniformity culminated in the procedures used during the Indian Ocean Survey. An improvement in system accuracy (Table 3) of approximately 1 part in 2000 shows that the effort to gravimetrically determine the pipette volumes on each leg was worthwhile. The volumes of both systems did decrease slightly but significantly with time. Possible explanations include pressure changes in the carrier gas source (system I) or fouling of the glass pipette walls causing altered surface tension or displacement of small amounts of liquid (system II). Because the samples were poisoned with HgCl(2), it is unlikely that biological fouling was a problem, but the high quantity of grease used to seal the CRM bottles makes it possible that some of this grease found its way into the pipettes. After cleaning, V(cal) for leg I10 remained unchanged compared to the preceding leg I1 on system I and increased slightly on system II, but for both systems it was significantly smaller than the V(cal) determined for the initial leg (I8SI9S). After cleaning, the mean analytical difference for leg I10 (system I and II, n=2) was -0.62 µmol/kg compared to -0.40 µmol/kg on the initial leg I8S when the instruments were fresh from the laboratory indicating that pipettes were most accurate after cleaning. Whatever the cause of subsequent volume changes, the data confirm the importance of periodically redetermining the volume, and indicate that the procedure is mandatory for the highest accuracy over extended periods of analytical work and/or after major changes in system plumbing. In aggregate, both systems share a small negative analytical difference (-1.0 µmol/kg) for the CRM analyses throughout the survey even after pipette volume corrections have been applied. The cell accuracy vs. carbon age relationship shown in Fig. 5 is typical of data from previous cruises (K.M. Johnson, unpublished data). The best precision and accuracy is found at a carbon age of 5-10 mg C, a slightly reduced accuracy (usually as lower recoveries of CRM carbon) is observed between 10-30 mg C, gradually increasing recoveries and imprecision after 30 mg C until cell death where cell death is defined as a positive difference ≥3.0 µmol/kg. This behavior underlies the recommendation that cell lifetimes be limited to a carbon age of ≤35 mg C, i.e., to limit imprecision and because cell death normally occurs at carbon ages ≥35 mg C. During the survey, neither CRM or samples were run until the carbon age exceeded 5 mg C. This was accomplished by configuring the software to automatically run a test sample and three consecutive gas calibrations before samples were analyzed. The reasons for the observed cell behavior are not understood, but limiting cell lifetimes from ≥5 to ≤35 mg C probably helps to limit system drift which might compromise the sample analyses. Although the imprecision associated with cell aging is small and cell failure is rare at carbon ages ≤35 mg C, good analytical practice requires that samples should be run in random order rather than systematically in order of depth to avoid systematic biases which might result from any drift associated with cell age. Fig. 4a and b shows no correlation between the gas calibration factors and the analytical differences after the CRM analyses were corrected for pipette volume changes (Table 3). These data do show that the overall mean gas calibration factor for both systems is nearly the same (1.004), but that the temporal record with respect to gas calibration factor variation is not. Calibration factor variation (R.S.D.=0.06-0.08%) is greater than the variation in V(cal) (R.S.D.=0.03%), and is therefore a potentially more important control on system accuracy. For system I, the highest mean gas calibration factor (poorest recovery of CO2) was observed on leg I8N, while for system II, the corresponding result occurred months later, on leg I7N (same measurement group, see Table 1). Because the system calibration factors are not correlated with the analytical differences, the observed variations in calibration factors are real, i.e., they document a change in system response shared by the calibration and sample analyses rather than an isolated malfunction of the gas calibration hardware (see Fig. 2). The reason for gas calibration factor variation is not known. It could conceivably be due to procedures unique to each measurement group, e.g., positioning of the cathode electrode and the gas inlet tube with respect to the coulometer light source and photodetector (Fig. 3), plumbing differences resulting in leaks and small losses of CO2, or the amount of reagents used to dry the gas stream (Fig. 2). These procedural differences would affect sample determinations and gas calibration results similarly because, as Fig. 2 shows, the calibration gas follows the same route to the coulometer as the CO2 extracted from samples. Table 3 suggests at least one other possible cause of gas calibration factor variation. The coulometers were electronically calibrated by the BNL group at the start of the survey (I8SI9S) and about half way through the survey on leg I5WI4. Between legs I8SI9S and I5WI4 the coulometer calibration appears to have changed by 0.08% for system I, and by 0.02% for system II. These calibrations were separated by many weeks so the exact magnitude or timing of the shift is not known. Changes in the coulometer's circuitry affecting the electronic slope (Slope(ec)) and intercept (Int(ec)) would alter the gas calibration factor but would not affect system accuracy because, until recalibration, the previous electronic calibration coefficients represent constants in Eq. 1. In both systems, the sense of the apparent change in electronic calibration coefficients compared to the earlier coefficients is qualitatively consistent with the observed short-lived variation in gas calibration factors, and it is possible that this variation was due to unexplained changes in the coulometer response. The important point is the efficacy of the gas calibration procedure: corrections to data based solely on the CRM analyses which would usually be applied on a cruise-average basis may mask short term variation or step changes in system response arising from stochastic or procedural changes. The gas calibration procedure, in which known masses of pure CO2 are regularly analyzed, is an independent check of all system components except pipette volume, and it provides traceable documentation for the subsequent survey results. The importance of cell assembly selection should be stressed. Investigators have found that the behavior of individual cell assemblies can vary significantly (e.g., D. Chipman, personal communication, July 1996). The factors affecting cell performance are still not yet completely understood. Hence, the use of empirical selection criteria such as those given in Section 2 is recommended. It is beyond the scope of the paper to go into detail, but point 'a' in Fig. 3 illustrates one of the locations for potential problems. A faulty seal where the platinum electrode emerges from the glass insulator could allow infiltration and trapping of the cell solution in the insulator where electrochemical or chemical reactions could take place. Small quantities of this solution (at a pH different from the bulk cell solution) could randomly exchange with the bulk cell solution and cause titration errors. This would be difficult to detect. Assemblies which did not meet the empirical performance criteria in Section 2 were simply not used. The attention to cell assembly testing and selection is believed to a major reason for the success of the Indian Ocean TCO2 Survey. The survey assemblies were also carefully washed and dried. Drying at 55±5°C removes traces of the volatile and reactive cell solution from the rubber caps. TABLE 4: Results of the crossover analysis (see text for details) __________________________________________________________________ Crossover Expedition legs Stations TCO2 difference no. Late Early Late Early ±S.D.(µmol/kg) --------- ---------------- ------------------ --------------- 1 I1 I7N 927:931 780:784 -2.5±0.5 2 I1 I9N 987:990 266:270 -2.7±6.3(a) 3 I1 I9N 996:998 233:235 -0.9±1.7 4 I2 I7N 1205 728:730 -0.4±1.1 5 I2 I8NI5E 1137:1139 320:324 1.5±1.5 6 I2 I9N 1094:1096 191:193 -3.0±0.7 7 I2 I10 1078 1075 -1.5±1.5 8 I5WI4 I3 705 547:549 1.6±0.5 9 I3 I8NI5E 498:501 346:348 -2.6±0.7 10 I3 I9N 472 169 1.1±1.2 11 I10 I3 1039 452:454 1.1±0.3 12 I8NI5E I8SI9S 404:408 9:13 -1.1±1.0 13 I1 I7N 861 808 1.3±0.4(b) Mean -0.78 __________________________________________________________________ The TCO difference between legs is calculated by subtracting data from the earlier sampling of a crossover location from that of the later sampling. The station numbers refer to the actual stations used for this analysis. (a) The LOESS fit diverged significantly from the data. (b) Not considered reliable due to insufficient data. 5. CROSSOVER ANALYSIS The agreement between TCO2 measurements made at similar locations, but on different legs of the survey, were used as a check on the internal consistency of the measurements. Deep measurements were used because of the lower variabil- ity in TCO2 observed in the deep ocean. Because most motion in the ocean interior takes place along surfaces of constant density (isopycnals), comparisons were made along isopycnal surfaces rather than depth. Our crossover analysis was performed as follows: (1) Locations at which different cruise legs intersected were identified as 'crossover points.' These are identified in Table 4 and are plotted on Fig. 1. (2) Stations located in the immediate proximity of these crossover points, for which TCO2 data existed, were selected for the comparison. In general, stations located within 100 km of the crossover location were selected. (3) For water samples collected below 2500 m, smooth curves were fit through the TCO2 data as a function of the density anomaly referenced to 3000 dbar (sigma 3) using Cleveland's LOESS smoother (Cleveland and Devlin, 1988). A separate fit was performed to the data collected from each of the two intersecting legs. The tension parameter for the smoother was adjusted subjectively to give a 'reasonable' fit to the data at the majority of the crossover locations, and the same value for the tension parameter was used for all of the crossovers. Hence, while the fits to the data may not necessarily represent the best possible at each individual crossover point, the smoothing function has been consistently applied to all crossovers. (4) For each crossover, the difference between the two smooth curves was evaluated at 50 evenly spaced intervals which covered the density range over which the two data sets overlapped. A mean and a standard deviation of the difference between the two curves was estimated based on these 50 values, and these values are reported in Table 4. An illustration of a typical analysis, the fitted data for crossover 4, is plotted on Fig. 7. Fig. 7. An example of a crossover analysis using the TCO2 vs. density fits at crossover location #4. This location was first sampled on leg I7N in July 1995. It was resampled during January 1996 on leg I2. The TCO2 data from stations within 100 km of the crossover location and depths>2500 m have been plotted vs. the potential density anomaly referenced to 3000 dbar (sigma 3). The solid curves represent fits to the data using a LOESS smoother (see text). The difference between the fits for the two separate legs was evaluated at 50 density intervals spaced evenly within the overlapping density range of the two legs (see Table 4). The legend shows the station numbers used for the comparison. The results of the crossover analysis indicate that absolute leg-to-leg differences are always <3.0 µmol/kg (Table 4). Note that the comparisons were evaluated consistently such that the fit to data from the earlier leg at each crossover was subtracted from the fit to the later leg's data. Any uncorrected, long-term, monotonic drift in the calibration of the SOMMA analyzers over the course of the Indian Ocean expedition would therefore result in a non-zero value for the overall mean of these differences. The overall mean and standard deviation of the differences at crossovers 1-12 is -0.78 (±1.74) µmol/kg, and there was also no significant correlation between the individual differences derived from each crossover and the number of days which separated the crossover samplings. In general, the results of the crossover analysis are quite consistent with the overall precision (±1.2 µmol/kg) of the CRM analyses (see Section 3.3), and confirms that this precision applies to both systems throughout the survey. There is no suggestion in the crossover results of any additional significant sources of error or uncertainty. 6. CONCLUSIONS In summary, personnel aboard the R/V Knorr have been able to use the SOMMA- coulometer system to consistently replicate within analytical error the certified CRM TCO2 values. They have been able to use these systems to make, counting duplicates and CRM, over 20,000 determinations of TCO2 during the 14 months of the Indian Ocean Survey without significant instrument down time. The measurement groups have accomplished the following. (1) They have charted the history of the to-deliver volume of the sample pipettes by gravimetric determinations, and corrected the water sample data for the documented changes in the pipette volumes. The change in system response due to the change in pipette volume corresponded to approximately 1 part in 2000 for TCO2 on both systems over the 10 months prior to recleaning of the pipettes. (2) The groups have determined that the survey precision for the TCO2 analyses, irrespective of which leg or system the water samples were analyzed on, was ±1.2 µmol/kg. The precision of the two instruments was nearly identical and consistent throughout the 14 months of the survey. (3) They have analyzed nearly 1000 CRM with an overall difference between the analyzed and certified TCO2 of -1.0 µmol/kg (0.05%) on both systems which demonstrates the equivalency of the two independent instruments, and meets the survey's goal for accuracy. (4) The measurement groups have documented the influence of factors besides pipette volume which could have affected accuracy including electronic calibration, gas calibration, cell age, and cell assembly selection. For precision, the pooled standard deviation (sp^2=1.2 µmol/kg), calculated according to Youden (1951), is the most conservative estimate of precision because it includes all random analytical errors (sampling, instrumental, and method). The identical accuracy for the CRM analyses on both systems and the results of the crossover analysis (Table 4) indicate that the sp^2 statistic can be used to evaluate survey data sets irrespective of the leg or system the data originated from. The SOMMA-coulometry systems have allowed several scientific groups in a shared effort to examine carbon inventories and aquatic carbon cycling. For the Indian Ocean Survey, the sensitivity of the TCO2 determinations defined as the ratio of their precision (1.2 µmol/kg) over the TCO2 dynamic range (250 µmol/kg) was 0.4% which approaches the 0.1% sensitivity of the salinometers used, and these systems were as reliable as the salinometers. If their reliability is to be improved, the focus should be on understanding the basic behavior of the cell assemblies and the chemical behavior of the cell solutions as they age, so that procedural corrections can be made. The accuracy and precision of the Indian Ocean TCO2 analyses indicates that these data will be more than adequate for testing applicable oceanographic models, and allow the direct measurement of the CO2 uptake if and when these lines are resampled. ACKNOWLEDGEMENTS We would like to thank the US Department of Energy's Office of Biological and Environmental Research for their support. The success of the Indian Ocean CO2 Survey was due to the shared efforts of the DOE Science Team. We thank John Downing for his initial organization of the Science Team and assistance in getting the US CO2 Survey underway. We thank the chief scientists, scientific staff, and crew aboard the R/V Knorr for their assistance throughout. Dave Chipman and Taro Takahashi are acknowledged for helpful comments and advice. The instruments used for the survey were produced at the Equipment Development Laboratory (EDL) at the University of Rhode Island's Graduate School of Oceanography under the supervision of Dr. John King and David Butler. This research was performed under the auspices of the United States Department of Energy under Contract No. DE-AC02-98CH10886. REFERENCES Bates, N.R., Michaels, A.F. and Knap, A.H., 1996. Seasonal and interannual variability of oceanic carbon dioxide species at the US JGOFS Bermuda Atlantic time-series study (BATS) site. Deep-Sea Research II 43, pp. 347-383 Cleveland, W.S. and Devlin, S.J., 1988. Locally-weighted regression: an approach to regression analysis by local fitting. J. Am. Stat. Assoc. 83, pp. 596-610 Dickson, A.G., 1990. The oceanic carbon dioxide system: planning for quality data. US JGOFS News 2:2. DOE, 1994. Handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water; version 2.0. ORNL/CDIAC-74. Huffman Jr., E.W.D., 1977. Performance of a new automatic carbon dioxide coulometer. Microchem. J. 22, pp. 567-573 Johnson, K.M., 1995. Operator's Manual. Single-Operator Multiparameter Metabolic Analyzer (SOMMA) for Total Carbon Dioxide (CT) with Coulometric Detection. Version 3.0. Available from K.M. Johnson, Department of Applied Science, Brookhaven National Laboratory, Upton, NY. Johnson, K.M., Wallace, D.W.R., 1992. The single-operator multiparameter metabolic analyzer for total carbon dioxide with coulometric detection. DOE research summary no. 19. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, TN. Johnson, K.M., King, A.E. and Sieburth, J.McN., 1985. Coulometric TCO2 analyses for marine studies: an introduction. Mar. Chem. 16, pp. 61-82 Johnson, K.M., Sieburth, J.McN., Williams, P.J.leB. and Bränström, L., 1987. Coulometric TCO2 analysis for marine studies: automation and calibration. Mar. Chem. 21, pp. 117-133 Johnson, K.M., Wills, K.D., Butler, D.B., Johnson, W.K. and Wong, C.S., 1993. Coulometric total carbon dioxide analysis for marine studies: maximizing the performance of an automated gas extraction system and coulometric detector. Mar. Chem. 44, pp. 167-187 Millero, F.J. and Poisson, A., 1981. International one-atmosphere equation of state for sea water. Deep-Sea Res. 28, pp. 625-629 Millero, F.J., Dickson, A.G., Eischeid, G., Goyet, C., Guenther, P., Johnson, K.M., Lee, K., Purkerson, D., Sabine, C.L., Key, R., Schottle, R.G., Wallace, D.W.R., Lewis, E.R. and Winn, C.D., 1998. Assessment of the quality of the shipboard measurements of total alkalinity on the WOCE Hydrographic Program Indian Ocean CO2 survey cruises 1994-1996. Mar. Chem. 63, pp. 9-20 Sabine, C.L., Key, R.M., 1998. Surface water and atmospheric underway carbon data obtained during the world ocean circulation experiment Indian Ocean survey cruises (R/V Knorr, December 1994-January 1996). NDP-064, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, TN. Taylor, J.K., 1990. Statistical techniques for data analysis. Lewis Publishers, Chelsea, 200 pp. Wilke, R.J., Wallace, D.W.R. and Johnson, K.M., 1993. A water-based, gravimetric method for the determination of gas sample loop volume. Anal. Chem. 65, pp. 2403-2406 Youden, W.J., 1951. Statistical Methods for Chemists. Wiley, New York, 126 pp. APPENDIX C: REPRINT OF PERTINENT LITERATURE Millero F.J., A.G. Dickson, G. Eischeid, C. Goyet, P. Guenther, K.M. Johnson, R.M. Key, K. Lee, D. Purkerson, C.L. Sabine, R.G. Schottle, D.W. .R. Wallace, E. Lewis and C.D. Winn, Assessment of the quality of the shipboard measurements of total alkalinity on the WOCE Hydrographic Program Indian Ocean CO2 survey cruises 1994-1996, Marine Chemistry 63:9-20. Marine Chemistry 63 1998 9 - 20 ASSESSMENT OF THE QUALITY OF THE SHIPBOARD MEASUREMENTS OF TOTAL ALKALINITY ON THE WOCE HYDROGRAPHIC PROGRAM INDIAN OCEAN CO2 SURVEY CRUISES 1994-1996 Frank J. Millero(a,*), Andrew G. Dickson(b), Greg Eischeid(c), Catherine Goyet(c), Peter Guenther(b), Kenneth M. Johnson(d), Robert M. Key(e), Kitack Lee(f), Dave Purkerson(a), Christopher L. Sabine(e), Rolf G. Schottle(g), Douglas W. R. Wallace(d), Ernie Lewis(d) and Christopher D. Winn(g) (a) Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA (b) Scripps Institution of Oceanography, University of California, La Jolla, San Diego, CA 92093, USA (c) Woods Hole Oceanographic Institute, Woods Hole, MA 02543, USA (d) Department of Applied Science, Brookhaven National Laboratory, Upton, NY 111973, USA (e) Department of Geosciences, Princeton University, Princeton, NJ 08544, USA (f) NOAA/AOML, Miami, FL 33149, USA (g) Department of Oceanography, University of Hawaii, Honolulu, HI 96822, USA *Corresponding author. Received 16 January 1998; revised 31 March 1998; accepted 7 April 1998. Available online 8 December 1998. ABSTRACT In 1995, we participated in a number of WOCE Hydrographic Program cruises in the Indian Ocean as part of the Joint Global Ocean Flux Study (JGOFS) CO2 Survey sponsored by the Department of Energy (DOE). Two titration systems were used throughout this study to determine the pH, total alkalinity (TA) and total inorganic carbon dioxide (TCO2) of the samples collected during these cruises. The performance of these systems was monitored by making closed cell titration measurements on Certified Reference Materials (CRMs). A total of 962 titrations were made on six batches of CRMs during the cruises. The reproducibility calculated from these titrations was ±0.007 in pH, ±4.2 µmol/kg-1 in TA, and ±4.1 µmol/kg-1 in TCO2. The at-sea measurements on the CRMs were in reasonable agreement with laboratory measurements made on the same batches. These results demonstrate that the CRMs can be used as a reference standard for TA and to monitor the performance of titration systems at sea. Measurements made on the various legs of the cruise agreed to within 6 µmol/kg-1 at the 15 crossover points. The overall mean and standard deviation of the differences at all the crossovers are 2.1±2.1 µmol/kg-1. These crossover results are quite consistent with the overall reproducibility of the CRM analyses for TA (±4 µmol/kg-1) over the duration of the entire survey. The TA results for the Indian Ocean cruises provide a reliable data set that when combined with TCO2 data can completely characterize the carbonate system. Author Keywords: alkalinity; WOCE Hydrographic Program; CO2 Index Terms: reproductive toxicity; boron 0304-4203r98r$ - see front matter q 1998 Elsevier Science B.V. All rights reserved. PII: S0304-42039800043-7 ARTICLE OUTLINE 1. Introduction 2. Methods 2.1. Titration system 2.1.1. Electrodes 2.1.2. Standard acids 2.1.3. Volume of the cells 2.1.4. Volume of titrant 2.2. Evaluation of the carbonate parameters 3. Results and discussion 3.1. Laboratory ta measurements of CRMs 3.2. At sea measurements of TA, TCO2, and pH on CRMs 3.2.1. Accuracy of at sea measurements 3.2.2. Long term stability of a cell performance 3.3. Crossover analysis 4. Conclusion Acknowledgements References 1. INTRODUCTION From 1994 to 1996, a number of cruises were made in the Indian Ocean as part of the World Ocean Circulation Experiment (WOCE) Hydrographic Program to characterize the carbon dioxide system. This survey of CO2 was an integral part of the Joint Global Ocean Flux Study (JGOFS). The goals of this survey were to: (1) Quantify the uptake of anthropogenic carbon dioxide by the oceans to better predict future atmospheric carbon dioxide levels; (2) Provide a global description of the carbon dioxide in the oceans to aid in the development of a 3-dimensional model of the oceanic carbon cycle; and (3) Characterize the transport of CO2 across the air-sea interface and the large scale transports of carbon dioxide within the oceans. To satisfy these goals, it was necessary to make very precise measurements of at least two of the carbonate system parameters (pH; total alkalinity, TA; total carbon dioxide, TCO2; and the fugacity of carbon dioxide, fCO2). Within the United States a large part of this survey was conducted by a team of investigators supported by the US Department of Energy. The team selected the measurement of TCO2 (Johnson et al., 1998) and of TA as the parameters to be measured in the water column and fCO2 in the atmosphere and surface waters. To insure that the measurements of TCO2 and TA were as precise and accurate as possible Certified Reference Materials (CRMs) (Dickson, 1990a) were used throughout the studies. The team also developed a set of Standard Operating Procedures1 (DOE, 1994) and, to a large extent, shared a common approach to the measurement program. For the studies in the Indian Ocean, the team shared equipment throughout the study. This paper presents the results of this team effort to precisely and accurately determine the total alkalinity during these cruises and the intercomparison between cruises. A companion paper (Johnson et al., 1998) describes the total carbon dioxide measurements. (1) DOE, 1991. Handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water, In: Dickson, A.G., Goyet, C. (Eds.), Version 1.0, Unpublished manuscript 2. METHODS The total alkalinity was determined on the JGOFS Indian Ocean cruises by the DOE group using systems described in detail by Millero et al. (1993). The total alkalinity of seawater was evaluated from the proton balance at the alkalinity equivalence point, pHequiv4.5, according to the exact definition mmmm of total alkalinity (Dickson, 1981) TA = [HCO¯(3)]+2[CO(3)(^2¯)]+[B(OH)¯(4)] +[OH¯]+[HPO^2¯(4)]+2[PO^3¯(4)] +[SiO(OH)¯(3)]+[HS¯]+[NH(3)] -[H+]-[HSO¯(4)]-[HF]-[H(3)PO(4)] (1) At any point in the titration, the total alkalinity of seawater can be calculated from the equation (W(0) x TA-W x C(HCl))/(W(0)+W) = [HCO¯(3)] +2[CO^2¯(3)]+[B(OH)¯(4)]+[OH¯] +[HPO^2¯(4)]+2PO^3¯(4)]+SiO(OH)¯(3)] +[HS¯]+[NH(3)]-[H+] -[HSO¯(4)]-[HF]-[H(3)PO(4)] (2) where W0 is the mass of the sample to be titrated, CHCl is the concentration of acid titrant, and W is the mass of acid added. In the calculations, volumes of the sample and of the acid were converted to mass using the density of seawater (Millero and Poisson, 1981) and the density of HCl in NaCl (Millero et al., 1977). Direct measurements made on the density of the acid used agreed to within 10 ppm with the equations used in the computer code. At the endpoint (W2) the total alkalinity is given by TA = W2 x C(HCl)/W(0) (3) The uncertainties in TA associated with acid concentration (0.25±0.0001 M), mass of acid delivered (2.5±0.0005 g), and mass of the sample (200±0.05 g) are ±1, ±0.5, and ±0.5 µmol/kg-1, respectively (which gives a probable error of about ±1 µmol/kg-1). By using the same acid, titrators, and acid throughout a given cruise one can obtain a precision that is comparable with this probable error. Discussed below are more details on the components of the titration systems. 2.1. TITRATION SYSTEM The titration systems used to determine TA consist of a Metrohm 665 Dosimat titrator and an Orion 720A pH meter controlled by a personal computer (Millero et al., 1993). Both the acid titrant in a water-jacketed burette and the seawater sample in a water-jacketed cell were controlled to a constant temperature of 25±0.1°C with a Neslab constant temperature bath. The plexiglass water-jacketed cells used for our studies were similar to that used by Bradshaw and Brewer (1988) except a larger volume (about 200 cm3) was used to improve the precision. These cells have fill and drain valves that increased the reproducibility of the cell volume. A Lab Windows C program is used to run the titration and record the volume of the added acid and the emf of the electrodes using RS232 interfaces. The titration is made by adding HCl to seawater past the alkalinity end point. A typical titration records the average of ten emf readings after they become stable (±0.09 mV) and adds enough acid to change the voltage by a pre- assigned increment (13 mV). In contrast to the delivery of a fixed volume of acid, this method gives more data points in the range of a rapid increase in the emf near the endpoint. A full titration (25 points) takes about 20 min. 2.1.1. ELECTRODES The electrodes used to measure the emf of the sample during a titration consist of a ROSS glass pH electrode and an Orion double junction Ag, AgCl reference electrode. A number of electrodes were screened to select those to be used in the titrators. Electrodes with non-Nernstian behavior (slopes more than 1.0 mV different from the theoretical value) were discarded. The reliability of the electrodes was evaluated by determining the TA, TCO2 and pH of Gulf Stream seawater. The titration values of TCO2 are normally higher than the values measured by coulometry and the values of pH are typically lower than the values obtained by spectrophotometric methods. These differences in TCO2 and pH are caused by the non-Nernstian behavior of the electrodes (Millero et al., 1993). We selected electrodes which gave values of TCO2 and pH close to the values determined by coulometric and by spectrophotometric methods, respectively. 2.1.2. STANDARD ACIDS The HCl used for this study and for all of our cruises was made in the laboratory, standardized, and stored in 500 cm3 glass bottles. The 0.25 M HCl solutions were made from 1 M Mallinckrodt standard solutions in 0.45 M NaCl to yield an ionic strength equivalent to that of average seawater (0.7 M). The concentration of HCl was measured using a constant current coulometric technique (Taylor and Smith, 1959; Marinenko and Taylor, 1968). Coulometric analysis of the acids used for these cruises agreed to ±0.0001 M with the analyses performed independently on the same batches of acids in Dr. A. Dickson's laboratory at Scripps Institution of Oceanography (SIO). The mutual consistency of these acids was also confirmed by comparing the values of TA measured on Gulf Stream seawater using different batches of acids, but using the same titrator and electrodes. The uncertainties in TA associated with acid concentration (±0.0001 M) is 1 µmol/kg-1. 2.1.3. VOLUME OF THE CELLS The volume of each of the titration cells used at sea was determined by comparing the values of TA obtained for Gulf Stream seawater with open and closed cells in the laboratory. All of the open cell laboratory TA measurements were made with weighed amounts of seawater in a cell with a small head-space. If the volume is correct, the TA from the open and closed cells should be the same, provided that the same acid, titrator, and electrodes are used. At least 10 measurements were made on each cell yielding an average TA that agreed with the assigned value to better than 1 µmol/kg-1. If the volume of a titration cell needed to be adjusted during the cruise (because of broken electrodes, plungers etc.), the volumes were determined from the daily titrations on low-nutrient surface seawater (usually collected before the first station) and Certified Reference Materials (CRMs) provided by Dr. A. Dickson (SIO). Post-cruise calibrations of the cells were made by comparing the values of TA for the Gulf Stream seawater and CRM with open and closed cells. The nominal volumes of all the cells were about 200 cm3, and the values were determined to ±0.05 cm3. The uncertainty in TA associated with this uncertainty in the volume of the cells (±0.05 cm3) is 0.5 µmol/kg-1 obtained for the weighed samples. 2.1.4. VOLUME OF TITRANT The volume of HCl delivered to the cell is traditionally assumed to have small uncertainty (Dickson, 1981) and equated to the digital output of the titrator. Calibrations of all the burettes of the Dosimats used were made with Milli-Q water at 25°C. Since the cell volumes are calibrated using standard solutions, errors in the accuracy of volume delivery will be partially canceled and included in the value of cell volumes assigned. The calibration of all the Dosimats used at sea and in the laboratory indicated that the amount of acid delivered (for a typical calculation) was uncertain to ±0.0005 cm3. This uncertainty in the volume delivered leads to an error in the TA of ±0.5 µmol/kg-1. Nevertheless, corrections to the Dosimat reading were made in all of our laboratory TA measurements and calibrations to insure that the assigned value for a different batch of CRM and Gulf Stream water was not affected by the use of different Dosimats. These corrections were also made when calculating the volume of each cell. 2.2. EVALUATION OF THE CARBONATE PARAMETERS A FORTRAN computer program has been developed to calculate the carbonate parameters (pH, E*, TA, TCO2, and pK(1)) in the seawater solutions. The program is patterned after those developed by Dickson (1981), Johansson and Wedborg (1982) and Dickson (1; DOE, 1994). The fitting is performed using the STEPIT routine (J.P. Chandler, Oklahoma State University, Stillwater, OK 74074). The STEPIT software package minimizes the sum of squares of residuals by adjusting the parameters E*, TA, TCO2 and pK(1) of carbonic acid. The computer program is based on Eq. 2 and assumes that nutrients such as phosphate, silicate and ammonia are negligible. This assumption is strictly valid only for surface waters. Neglecting the concentration of nutrients in the seawater sample does not affect the accuracy of TA, but must be considered when calculating the carbonate alkalinity (CA=[HCO¯(3)]+2 [CO^2¯(3)]) from TA. The pH and pK of the acids used in the program are on the seawater scale, [H+]sw[H+]+[HSO¯(4)]+[HF] (Dickson, 1984). The dissociation constants used in the program were taken from Dickson and Millero (1987) for carbonic acid, from Dickson (1990b) for boric acid, from Dickson and Riley (1979) for HF, from Dickson (1990c) for HSO¯(4) and from Millero (1995) for water. The program requires as inputs the concentration of acid, volume of the cell, salinity, temperature, measured emfs (E) and volumes of HCl (V). To obtain a reliable TA from a full titration, at least 25 data points should be collected (9 data points between pH 3.0 to 4.5). The precision of the fit is less than 0.4 µmol/ kg_1 when pK(1) is allowed to vary and 1.5 µmol/kg-1 when pK(1) is fixed. Our titration program has been compared to the titration programs used by others (Johansson and Wedborg, 1982; Bradshaw and Brewer, 1988) and the values of TA agree to within ±1 µmol/kg-1. 3. RESULTS AND DISCUSSION 3.1. LABORATORY TA MEASUREMENTS OF CRMS The laboratory TA measurements made on the CRMs used throughout this study are summarized in Table 1. The results obtained by both laboratories demonstrate that no systematic differences in TA are found. With the exception of Batch 29, the differences in the measurements of the CRMs between the two laboratories are less that 2 µmol/kg-1. Since the Miami measurements were made with the same acid as used at sea, one cannot attribute the differences in Batch 29 to differences in the concentration of the acids (calibrated at SIO). The Miami measurements were also made using the same acid for all the batches of CRM within a one-week period to ensure the internal consistency of its results. The measurements made on the acid concentration in Miami and SIO by a coulometric titration were in agreement to ±0.0001 M, which is equivalent to an error of ±1 µmol/kg-1 in TA. TABLE 1: Comparison of the total alkalinity of Certified Reference Materials _______________________________________________________________ Batch SIO Miami ∆(S-M) Cruise ----- ------ ------ ------ ------------------------------ 23 2212.7 2213.7 -1.0 I8S/I9S, I9N, I8N/I5E, I3, I7N 24 2215.5 2215.8 -0.3 I8R 26 2176.6 2175.1 1.5 I3, I5W/I4, I-7N 27 2214.9 2214.3 0.6 I7N, I1, I10, I2 29 2184.8 2182.3 2.5 I8R 30 2201.9 2200.5 1.4 I2 _______________________________________________________________ 3.2. AT SEA MEASUREMENTS OF TA, TCO2, AND PH ON CRMS 3.2.1. Accuracy of at sea measurements The tracts of the cruise made during the Indian Ocean studies are shown in Fig. 1. A total of 962 titrations were made on six batches of the CRMs during the cruises (Table 2). A summary of the pH, TA and TCO2 measurements made on CRMs (Table 3) throughout the cruise is shown in Fig. 2, Fig. 3 and Fig. 4. The reproducibility on the six batches of the CRMs used was ±0.007 in pH, ±4.2 µmol/kg-1 in TA, and ±4.1 µmol/kg-1 in TCO2. The at sea TA measurements on the CRMs were in good agreement (2-4 µmol/kg-1) with laboratory measurements made on the same batches at MIAMI and SIO. These small differences (2-4 µmol/kg-1) are well within the overall precision of our measurements and can be attributed to uncertainties in the volume of cells assigned in the laboratory before the cruises. However, the cells used on I7 gave significantly greater errors than the values obtained in the laboratories on the same batch of CRM. These large discrepancies might be attributed to inaccurately assigned volumes of the cells after they were repaired for leakage due to repositioning of a reference electrode after changing the inner filling solution. Fig. 1. Cruise tracts of the Indian Ocean Studies showing crossover points. TABLE 2: Measurements of pH, TA and TCO2 of CRM at sea ____________________________________________________________________________________ Cruise Start End Batch Cell N TA S.D. TCO2 S.D. pH S.D. date date avg avg avg ------- ------- ------- ----- ---- --- ------ --- ------ --- ----- ----- I8S/I9S 12/1/94 1/19/95 23 All 49 2221.5 5.1 2004.5 4.1 5 18 2223.3 4.8 2003.8 2.5 6 18 2220.8 4.0 2008.0 3.1 20 13 2220.0 6.4 2001.4 3.8 I9N 1/24/95 3/6/95 23 All 138 2216.2 3.3 2000.1 3.5 7.891 0.005 5 68 2215.0 3.3 1999.1 3.3 7.892 0.004 6 65 2217.5 3.3 2001.3 3.3 7.891 0.005 20 5 2214.2 3.1 1996.5 3.5 7.895 0.007 I8N/I5E 3/10/95 4/16/95 23 All 80 2211.6 4.9 1997.0 3.0 7.890 0.006 5 36 2213.0 5.5 1998.6 3.8 7.890 0.005 6 44 2210.1 3.6 1996.2 2.6 7.890 0.007 I3 4/20/95 6/7/95 23 All 65 2215.4 1.4 2002.1 1.4 7.894 0.005 2 33 2215.7 1.3 2000.7 1.4 7.898 0.006 13 35 2215.0 1.4 2003.6 1.3 7.890 0.004 26 All 30 2178.0 1.2 1984.8 1.2 7.858 0.004 2 14 2178.3 1.3 1983.3 1.2 7.862 0.003 13 16 2177.7 1.2 1986.0 1.1 7.855 0.004 I5W/I4 6/11/95 7/11/95 26 All 79 2182.6 3.8 1990.2 3.4 2 41 2183.3 3.9 1988.0 2.4 13 38 2182.0 3.5 1992.9 2.3 I7N 7/15/95 8/24/95 26 All 59 2184.0 5.7 1984.7 3.4 7.862 0.009 2 33 2186.2 3.1 1984.3 2.6 7.862 0.009 13 26 2181.5 7.4 1985.2 4.0 7.858 0.006 27 All 8 2221.5 3.1 1995.5 1.4 7.916 0.005 2 4 2221.4 2.4 1994.9 1.4 7.914 0.005 13 4 2221.5 4.1 1996.0 1.5 7.918 0.006 23 All 10 2222.4 7.4 2002.0 4.0 7.896 0.006 2 5 2227.5 5.8 2003.2 4.1 7.897 0.005 13 5 2216.2 6.4 1999.9 3.9 7.893 0.009 I1 8/29/95 10/18/95 27 All 244 2219.4 3.9 1998.8 5.4 7.906 0.013 2 123 2220.1 3.2 1995.3 3.2 7.911 0.005 7 54 2219.6 3.6 1999.7 4.1 7.908 0.013 13 15 2216.2 4.7 1994.6 4.5 7.909 0.005 14 52 2217.9 4.5 2006.5 3.6 7.885 0.009 I10 11/6/95 11/24/95 27 All 62 2212.9 4.0 1991.3 2.9 7.912 0.006 11 30 2212.3 4.5 1989.6 2.4 7.914 0.005 16 32 2213.5 3.5 1993.1 2.0 7.910 0.006 I8R 9/23/95 10/24/95 29 All 36 2184.2 1.8 1914.8 2.4 8.006 0.006 NOAA Cruise 4 9 2185.5 1.7 1914.5 1.9 8.006 0.005 17 17 2183.9 1.6 1914.4 2.2 8.007 0.005 18 10 2183.4 2.1 1915.7 3.1 8.004 0.009 24 All 10 2216.6 2.3 1998.7 1.7 7.902 0.006 4 2 2218.5 3.8 1998.6 3.9 7.907 0.004 17 5 2215.1 0.6 1998.5 1.4 7.902 0.006 18 3 2217.3 2.6 1998.6 1.7 7.899 0.006 I2 11/28/95 1/19/96 27 All 67 2219.4 4.5 1994.0 2.8 7.916 0.005 11 36 2219.9 5.7 1993.1 3.3 7.918 0.005 16 31 2218.9 3.2 1994.7 2.2 7.915 0.006 30 All 9 2204.6 2.7 1996.8 2.1 7.879 0.004 11 4 2205.3 2.3 1995.0 2.2 7.880 0.002 16 5 2204.0 3.0 1998.4 0.8 7.879 0.006 ____________________________________________________________________________________ TABLE 3: The overall precision of at sea TA, TCO2, and pH measurements on the Certified Reference Material _________________________________________ Precision 1σ Number of Parameters (µmol kg-1) measurements ---------- ------------- ------------ TA 4.2 949 TCO 4.1 9472 pH 0.007 793(a) _________________________________________ (a) The numbers of the pH measurements were less than for TA and TCO2 be- cause some values were not recorded. Fig. 2. The reproducibility of the titration pH measurements made on Certified Reference Material on the Indian Ocean Study. Fig. 3. The reproducibility of the titration TCO2 measurements made on Certified Reference Material on the Indian Ocean Study. Fig. 4. The reproducibility of the titration TA measurements made on Certified Reference Material on the Indian Ocean Study. 3.2.2. Long term stability of a cell performance The at sea TA measurements on the CRMs can be used to examine the long-term stability of the cells used during the cruises. Overall, the TA results obtained using cells for a given cruise did not show any systematic trends. Differences in TA between laboratory and field measurements remained unchanged over the entire period of each cruise. However, inter-cruise variations in TA between laboratory and field results were observed when the same cells were used. For instance, cells 2 and 13 were used for four consecutive cruises over the period of six months. When these two cells were used on the first cruise (I3), the field measurements agreed to within ±2 µmol/kg-1 with the values obtained in the laboratory. These small discrepancies are within the precision of our measurements. When the same cells were used for the later cruises, the differences in TA between laboratory and field measurements became significantly larger (9 µmol/kg-1). As mentioned in Section 3.2.1, these larger differences can be attributed to changes in the assigned volume of the cells due to repositioning of a reference electrode. These inter-cruise variations in TA can be corrected by normalizing the measured values obtained during the cruises using the corrections required to reproduce the values assigned for the CRMs by SIO (Table 4). This correction was applied using ∆ = TA(meas,CRM)-CRM) (4) TA(corr.) = TA(meas.) x [CRM/(CRM+∆)] (5) where CRM is the SIO-certified values. TABLE 4: Differences between TA measurements made at sea and values measured in the laboratory (SIO) ______________________________________________________________________________ Cell I8S/I9S I9N I8N/I5E I3 I5W/I4 I7N I1 I8R I10 I2 ---- ------- --- ------- ------ ------ ------ --- --- ---- ------- 2 +2.6(a) +6.7 +9.9(a) +5.2 4 0.7 5 +10.6 +2.3 +0.3 6 +8.1 +4.8 -2.6 7 +4.7 11 -2.6 +4.8(a) 13 +2.1(a) +6.0 +4.9(a) +1.3 14 +3.0 16 -1.4 +3.7(a) 17 -0.9 18 -1.4 20 +7.3 +1.5 ______________________________________________________________________________ (a)Based on the weighted average on different CRM. 3.3. CROSSOVER ANALYSIS In order to cross-check our estimates of accuracy of the TA data, which are derived from analyses of CRMs, we examined the agreement between TA measurements made at identical locations on different legs of the Indian Ocean expedition. All of these comparisons have been made after applying the corrections given in Table 4. The implicit assumption is that temporal and spatial gradients of TA concentrations in the deep ocean are small relative to measurement accuracy, so that water sampled at the same location in the deep ocean at two different times should have near-identical values of TA. In practice, vertical gradients of TA can be significant relative to measurement accuracy and there can also be significant vertical motions in the deep ocean. Hence, measurements made at the same geographical location cannot be compared simply on the basis of their common depth. Because most motion in the ocean interior takes place along surfaces of constant density (isopycnals), it is preferable to compare concentrations using density as the frame of reference rather than depth. TABLE 5: Crossover results for the TA measurements made in the Indian Ocean _________________________________________________ Number Stations Legs ∆TA ------ ------------ --------------- -------- 1 927,929,931, I1-I7N 1.7±1.0 780,782,784 2 987,990,266, I1-I9N -2.1±5.9 268,270 3 996,998, I1-I9Nb 1.2±0.8 233,235 4 1205,728, I2-I7N 5.6±2.4 730 5 1137,1139, I2-I9N/I5E 3.4±2.2 320,324 6 1094,1096, I2-I9N -3.4±1.4 191,193 7 1078,1075 I2-I10 1.8±2.4 8 705,547,549 I5W/I4-I3 0.7±1.7 9 498,499,501, I3-I8N/I5E -0.8±2.3 346,348 10 472,169 I3-I9N -0.8±0.6 11 1039,452,454 I10-I3 -1.0±0.7 12 404,406,408, I8N/I5E-I8S/I9S -2.7±3.8 9,11,13 13 861,808 I1-I7N 0.3±0.6 14 709,707 I7N-I5W/I4 2.4±1.7 15 966,968,969, I1-I8N/I5E -4.2±4.5 283,287 _________________________________________________ Our crossover analyses were performed as follows. (1) Locations at which different cruise legs intersected were identified as crossover points. These are identified in Table 5 and Fig. 1. (2) Stations located in the immediate proximity of these crossover points, for which TA data existed, were selected for the comparison. In general, stations located within 100 km of the crossover location were selected. (3) For water samples collected below 2500 m, smooth curves were fit through the TA data as a function of the density anomaly referenced to 3000 db (sigma-3) using Cleveland's loess or smoother local regression (Cleveland and Devlin, 1988; Cleveland and Grosse, 1991; Chambers and Hastie, 1991). A separate fit was performed to the data collected from each of the two intersecting legs. The tension parameter for the smoother was adjusted subjectively to give a 'reasonable' fit to the data at the majority of the crossover locations, and the same value for the tension parameter was used for all of the crossovers. Hence, while the fits to the data may not necessarily represent the best possible at each individual crossover point, the smoothing function has been applied consistently. It is important to note that the comparison of the data at the crossover points does not depend on the fitting algorithm within the experimental error. (4) For each crossover, the difference between the two smooth curves was evaluated at 50 evenly spaced intervals that covered the density range over which the two data sets overlapped. A mean and a standard deviation of the difference between the two curves was estimated based on these 50 values, and these values are reported in Table 5 and shown in Fig. 5. An example of the crossover for cruises I3-I5W/I4 is shown in Fig. 6. Fig. 5. Summary of the TA reproducibility for crossover points in the Indian Ocean. Fig. 6. Results for a typical crossover comparison (I3-I5W/I4) in the Indian Ocean. The results of the crossover analysis indicate that absolute leg-to-leg differences are always <6 µmol/kg-1. Note that the comparisons were evaluated consistently such that the fit to data from the earlier leg at each crossover was subtracted from the fit to the later leg's data. Any uncorrected, long- term, monotonic drift in the calibration of the titrators over the course of the Indian Ocean expedition would therefore tend to result in a non-zero value for the overall mean of these differences. The overall mean and standard deviation of the differences at all the crossovers are 2.1±2.1 µmol kg_1. In general, the results of the crossover analysis are quite consistent with the overall reproducibility of the CRM analyses (±4 µmol/kg-1) over the duration of the entire Survey. 4. CONCLUSION At-sea total alkalinity measurements on the several CRM batches demonstrated that the measurements made by various investigators were precise to about ±4 µmol/kg-1. This level of the precision of at sea measurements was approximately two times worse than that in the laboratory. Differences in the precision between different investigators suggest that the performance of TA measurements was dependent upon the operators. The inter-cruise variations in total alkalinity between laboratory and field results clearly demonstrate that CRMs are an essential component to monitor the performance of titration systems and increase the accuracy for total alkalinity measurements in the field. ACKNOWLEDGEMENTS The authors wish to acknowledge the support of the Department of Energy for their support of the CO2 studies. The WOCE cruises were supported by the National Science Foundation, as was some of the laboratory work related to the preparation and standardization of Certified Reference Material. REFERENCES Bradshaw, A.L. and Brewer, P.G., 1988. High precision measurements of alkalinity and total carbon dioxide in seawater by potentiometric titration: 1. Presence of unknown protolyte(s)?. Mar. Chem. 28, pp. 69-86 Chambers, J.M., Hastie, T.J., 1991. Stat. Models Sci., 309-376. Cleveland, W.S. and Devlin, S.J., 1988. Locally-weighted regression: an approach to regression analysis by local fitting. J. Am. Statist. Assoc. 83, pp. 596-610 Cleveland, W.S., Grosse, E., 1991. Computational Methods for Local Regression. Stat. Comput., Vol. 1. Dickson, A.G., 1981. An exact definition of total alkalinity and a procedure for the estimation of alkalinity and total CO2 from titration data. Deep-Sea Res. 28, pp. 609-623 Dickson, A.G., 1984. pH scales and proton-transfer reactions in saline media such as seawater. Geochim. Cosmochim. Acta 48, pp. 2299-2308 Dickson, A.G., 1990. The oceanic carbon dioxide system: planning for quality data. US JGOFS News 2 2, p. 10 Dickson, A.G., 1990. Thermodynamics of the dissociation of boric acid in synthetic seawater from 273.15 to 318.15 K. Deep-Sea Res. 37, pp. 755-766 Dickson, A.G., 1990. Standard potential of the (AgCl+1/2 H2=Ag+HCl(aq)) cell and the dissociation of bisulfate ion in synthetic sea water from 273.15 to 318.15 K. J. Chem. Thermodyn. 22, pp. 113-127 Dickson, A.G. and Riley, J.P., 1979. The estimation of acid dissociation constants in sea water media from potentiometric titrations with strong base: I. The ionic production of water-KW. Mar. Chem. 78, pp. 89-99 Dickson, A.G. and Millero, F.J., 1987. A comparison of the equilibrium constants for the dissociation of carbonic acid in seawater media. Deep-Sea Res. 34, pp. 1733-1743 DOE, 1994. Handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water, In: Dickson, A.G., Goyet, C. (Eds.), Version 2, ORNL/CDIAC-74. Johansson, O. and Wedborg, M., 1982. On the evaluation of potentiometric titrations of seawater with hydrochloric acid. Oceanol. Acta 5, pp. 209-218 Johnson, K.M., Dickson, A.G., Eischeid, G., Goyet, C., Guenther, P., Key, R.M., Millero, F.J., Purkerson, D., Sabine, C.L., Schottle, R.G., Wallace, D.R.W., Wilke, R.J. and Winn, C.D., 1998. Coulometric total carbon dioxide analysis for marine studies: Assessment of the quality of total inorganic carbon measurements made during the US Indian Ocean CO2 Survey 1994-1996. Mar. Chem. 63, pp. 21-37 Marinenko, G. and Taylor, J.K., 1968. Electrochemical equivalents of benzoic and oxalic acid. Anal. Chem. 40, pp. 1645-1651 Millero, F.J., 1995. The thermodynamics of the carbon dioxide system in oceans. Geochim. Cosmochim. Acta 59, pp. 661-677 Millero, F.J. and Poisson, A., 1981. International equation of state of seawater. Deep-Sea Res. 28, pp. 625-629 Millero, F.J., Laferriere, A. and Chetirkin, P.V., 1977. The partial molal volumes of electrolytes in 0.725 m sodium chloride solutions at 25°C. J. Phys. Chem. 81, pp. 1737-1745 Millero, F.J., Zhang, J.Z., Lee, K. and Campbell, D.M., 1993. Titration alkalinity of seawater. Mar. Chem. 44, pp. 153-160 Taylor, J.K. and Smith, S.W., 1959. Precise coulometric titration of acids and bases. J. Res. Natl. Bur. Stds. 63A, pp. 153-159 APPENDIX D: REPRINT OF PERTINENT LITERATURE Sabine, C. L., R. M. Key, K. M. Johnson, F. J. Millero, A. Poisson, J. L. Sarmiento, D. W. R. Wallace, and C. D. Winn (1999), Anthropogenic CO2 Inventory of the Indian Ocean, Global Biogeochem. Cycles, 13(1), 179-198. ANTHROPOGENIC CO2 INVENTORY OF THE INDIAN OCEAN C.L. Sabine,(1) R.M. Key,(1) K.M. Johnson,(2) F.J. Millero,(3) A. Poisson,(4) J.L. Sarmiento, D.W.R. Wallace,(2,5) and C.D. Winn,(6,7) (1) Department of Geosciences, Princeton University, Princeton, New Jersey. (2) Oceanographic and Atmospheric Sciences Division, Brookhaven National Laboratory, Upton, New York. (3) Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida. (4) Laboratoire de Physique et Chimie Marines, Universite Pierre et Marie Curie, Paris. (5) Now at Institut für Meereskunde, Universität Kiel. (6) Department of Oceanography, University of Hawaii at Manoa, Honolulu, Hawaii. (7) Now at Hawaii Pacific University, Kaneohe, Hawaii. GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 13, NO.1, PAGES 179-198, MARCH 1999 Copyright 1999 by the American Geophysical Union. Paper number 1998GB900022. 0886-62361991l998GB900022$12.00 ABSTRACT. This study presents basin-wide anthropogenic CO2 inventory estimates for the Indian Ocean based on measurements from the World Ocean Circulation Experiment/Joint Global Ocean Flux Study global survey. These estimates employed slightly modified ∆C* and time series techniques originally proposed by Gruber et al. [1996] and Wallace [1995], respectively. Together, the two methods yield the total oceanic anthropogenic CO2 and the carbon increase over the past 2 decades. The highest concentrations and the deepest penetrations of anthropogenic carbon are associated with the Subtropical Convergence at around 30° to 40°S. With both techniques, the lowest anthropogenic CO2 column inventories are observed south of 50°S. The total anthropogenic CO2 inventory north of 35°S was 13.6±2 Pg C in 1995. The inventory increase since GEOSECS (Geochemical Ocean Sections Program) was 4.1±1 Pg C for the same area. Approximately 6.7±1 Pg C are stored in the Indian sector of the Southern Ocean, giving a total Indian Ocean inventory of 20.3 ±3 Pg C for 1995. These estimates are compared to anthropogenic CO2 inventories estimated by the Princeton ocean biogeochemistry model. The model predicts an Indian Ocean sink north of 35°S that is only 0.61-0.68 times the results presented here; while the Southern Ocean sink is nearly 2.6 times higher than the measurement-based estimate. These results clearly identify areas in the models that need further examination and provide a good baseline for future studies of the anthropogenic inventory. 1. INTRODUCTION The current Intergovernmental Panel on Climate Change (IPCC) estimate for the oceanic sink of anthropogenic CO2 (2.0 ±D.8 Pg C yr-I) is based primarily on ocean models [e.g., Sarmiento et al., 1992; Sarmiento and Sundquist, 1992; Siegenthaler and Sarmiento, 1993; Siegenthaler and Joos, 1992; Stocker et al., 1994], atmospheric models [e.g., Keeling et al., 1989; Keeling and Shertz, 1992] or on the oceanic distribution of related species such as δ13C [Quay et al., 1992]. Although the basic assumptions used in these methods are reasonably well grounded, there will always be room for doubt with indirect approaches. Direct estimates of the oceanic CO2 sink, however, have been primarily limited by a lack of high-quality data on a global scale. Two general approaches can be used to estimate the uptake of anthropogenic CO2 by the oceans. One approach, initially proposed by Tans et al. [1990], is to use direct measurements of the air-sea difference in CO2 partial pressure together with global winds and a gas exchange coefficient to estimate the net transfer of CO2 into the oceans. These estimates, together with an atmospheric transport model, predicted that the oceanic sink was only 0.3 to 0.8 Pg C yr-', much smaller than the model predictions. The difficulty with the ∆C02 approach lies both in the large uncertainty in the wind speed dependence of the air-sea gas exchange velocity and in the ability to properly represent the large temporal and spatial variability of the surface ocean pC02 because of a lack of seasonal, global data coverage. This estimate has recently been revised to 0.6 to 1.34 Pg C yr-I with the addition of more data and a lateral advection-diffusion transport equation to help with the necessary temporal and spatial interpolations [Takahashi et al., 1997]. A second approach, which avoids many of the problems of temporal variability, is to estimate the inventory of anthropogenic CO2 stored in the oceans interior based on inorganic carbon measurements. Again, the problem with this approach in the past has been a lack of high-quality global data coverage. As pointed out by Broecker et al. [1979] after completion of the last global oceanographic survey, GEOSECS (Geochemical Ocean Sections Program), the precision of ocean carbon measurements at that time was two orders of magnitude smaller than the predicted 0.035% annual increase in surface ocean dissolved inorganic carbon. Nearly 20 years have passed since GEOSECS, and the quality of today's carbon measurements has improved significantly. This is the first of several papers aimed at estimating the anthropogenic CO2 inventory of the oceans based on the recent global survey of CO2 in the oceans. The survey was conducted as part of the JGOFS (Joint Global Ocean Flux Study) in close cooperation with the WOCE-HP (World Ocean Circulation Experiment - Hydrographic Programme). This program was a multiyear effort to collect high-precision inorganic carbon data with the highest possible spatial resolution on a global scale. This paper will focus on anthropogenic CO2 estimates for the Indian Ocean. Papers will soon follow with estimates for the other major ocean basins, with the ultimate goal of generating an estimate of the global oceanic anthropogenic CO2 sink based on direct carbon system measurements. The strength of these calculations lies not only in our ability to directly estimate the magnitude of the oceanic anthropogenic CO2 sink but also in the fact that these estimates can be directly compared to anthropogenic CO2 inventories estimated by carbon cycle ocean general circulation models (GCMs). The two methods described here provide information over different timescales. The combined results place strong constraints on the uptake rate for anthropogenic CO2 and are useful for identifying weaknesses in the models. 2. METHODS Estimates of the anthropogenic CO2 inventory are determined from measured values using two different techniques. The first technique, referred to as the "time series" approach, is based on quantifying the increase in total carbon dioxide (TC02) since GEOSECS. The second approach quantifies the total anthropogenic CO2 inventory using a quasi-conservative tracer, ∆C*. Although the general idea for both techniques has been around for a long time, recent improvements in the estimation of the preserved end-member concentrations together with significant Improvements in the accuracy and spatial coverage of global carbon data give us much more confidence in these results. Given the difficulty of isolating the anthropogenic signal from the large TC02 background, however, it is relevant to summarize the quality of the carbon data set and the techniques used to estimate the anthropogenic signal. 2.1. DATA QUALITY Over 20,000 water samples collected between December 1994 and July 1996 as part of the U.S. WOCE Indian Ocean survey were analyzed for both TC02 and total alkalinity (TA) using standard coulometric and potentiometric techniques, respectively. Figure 1 shows the locations of the 1352 stations occupied by U.S. WOCE as part of the Indian Ocean survey together with the station locations from the GEOSECS Indian Ocean Survey and the French INDIGO I, II, and III and CIVA-1 (WOCE designation I6S) Cruises Details of the WOCE/JGOFS Indian Ocean CO2 measurement program, including personnel, sampling procedures, measurement protocols and data quality assurance/quality control checks are described elsewhere [Johnson et al., 1998; Millero et al., 1998a]. Calibrations of both the TC02 and TA systems were checked approximately every 12 hours by analyzing Certified Reference Material (CRM) samples with known concentrations of TC02 and TA [Dickson, 1990] (A.G. Dickson, Oceanic carbon dioxide quality control at http://www-mpl.ucsd. edulpeople/adicksonlC02_QC/, 1998). On the basis of these CRM analyses the accuracy of the TC02 and TA measurements was estimated to be ±2 and ±4 µmol kg-1, respectively. Primary hydrographic data from the conductivity- temperature-depth/Rosette were collected and analyzed following standard procedures [Millard, 1982]. Samples were collected for salinity on every bottle and analyzed with an Autosal salinometer using standard techniques [UNESCO, 1981]. Oxygen samples were analyzed with an automated system using a modified Winkler technique [Culberson et al., 1991]. Nutrients were analyzed on a four-channel Technicon AutoAnalyzer II following the methods of Gordon et al. [1992]. Chlorofluorocarbon samples were analyzed on a gas chromatograph using the techniques of Bullister and Weiss [1988]. Complete details of the analytical protocols and personnel can be obtained from the individual cruise reports available through the WOCE Office. FIGURE 1: Station locations for WOCE Indian Ocean (circles), CIVA-1/I6S (crosses), INDIGO I (stars), INDIGO II (inverted triangles), INDIGO III (triangles), and GEOSECS (solid squares) Indian Ocean Surveys. Numbered boxes indicate location of crossovers discussed in the text. Map generated using Generic Mapping Tools version 3 [Wessel and Smith, 1995]. All of the data available at the time this manuscript was written have been included in the Indian Ocean analysis. For the primary hydrographic and nutrient data this means that the preliminary values available at the conclusion of the cruise were used. While we would prefer to use the final hydrographic data, typical post cruise corrections for the WOCE data sets are well below noise level for these calculations. Preliminary to semifinal chlorofluorocarbon (CFC) data were used to estimate the water age necessary for one of the correction terms in the ∆C* method. Although post cruise blank corrections can influence the final CFC concentrations, an examination of the existing data (except 18NI5E because data were not available at time of writing) indicated that the CFC-ll and CFC-12 age comparisons as well as comparisons of the data from one leg to the next were reasonably consistent with each other. The calculations were limited to waters with CFC-12 ages of less than 40 years where potential blank corrections are a relatively small fraction of the signal and mixing effects are minimized. The carbon data, which primarily influence the quality of the calculations, have all been calibrated and finalized as discussed briefly below. Examination of Figure 1 reveals that although the WOCE survey was extensive, a large data gap exists in the southwestern Indian Ocean. To fill in this gap, data from the three French survey legs INDIGO I (February-March 1985), IT (April 1986) and 1lI (January-February 1987) as well as the more recent French cruise CIVA-1 (February-March 1993 (WOCE designation 16S» were included in the analysis [Poisson et al., 1988; 1989; 1990]. TC02 and TA were analyzed on the INDIGO cruises using standard potentiometric titration techniques developed by Edmond [1970]. Potentiometric titrations were also used to analyze the TA samples on CIVA-1, but the TC02 samples were analyzed using the coulometric techniques of Johnson et al. [1985]. The internal consistency of these cruises was examined by comparing carbon values in the deep waters (pressure> 2500 dbars) at the intersections of different legs. The stations selected for each crossover were those with carbon values which were closest to the intersection point. Smooth curves were fit through the data from each cruise as a function of sigma- 3 (density anomaly referenced to 3000 dbars) using Cleveland's loess function [Cleveland and Devlin, 1988; Cleveland et al., 1992]. The difference between the curves was evaluated at 50 evenly spaced intervals that covered the density range over which the two data sets overlapped. The mean and standard deviation of the difference in TA and TC02 at the 35 intersections identified in Figure 1 are shown in Figure 2. The long-term stability of the WOCE/JGOFS measurements can be estimated from the first 17 crossover results. The mean of the absolute values for the leg-to-leg differences was less than the estimated accuracy for both TC02 (1.8 ±0.8 µmol kg-1) and TA (2.4 ±1.6 µmol kg-1). Although there is only one reliable crossover point between the WOCE/JGOFS cruises and the CIVA-1 (I6S) cruise, the differences for both parameters are within the estimated accuracy of the measurements. Results from the analysis of CRM samples on the CIVA-1 cruise also support the quality of the measurements. Some of the older INDIGO cruises, however, did appear to have offsets relative to the WOCE/JGOFS and CIVA-1 data. INDIGO I and IT alkalinity values averaged 6.5 µmol kg-1 high and 6.8 µmol kg-1 low, respectively, while the INDIGO 1lI alkalinity values showed no clear offset. The INDIGO TC02 values were all consistently high relative to WOCE/JGOFS and CIVA-1, with differences of 10.7,9.4, and 6.4 µmol kg-1, respectively. These offsets are consistent with differences observed between at-sea values and replicate samples run at C.D. Keeling's shore-based TC02 facility (P. Guenther, personal communication, 1998). Since the INDIGO cruises were run prior to the introduction of CRMs, these offsets were presumed to be calibration differences, and each leg was adjusted to bring the values in line with the remaining cruises. The dotted boxes in Figure 2 show the original offsets at the crossovers. The solid boxes show the final offsets used in the following calculations. The means of the absolute values for the leg-to-leg differences for all 35 crossover analyses suggest that the final data set is internally consistent to ± 2.2 and 3.0 µmol kg-1 for TC02 and TA, respectively. 2.2. "TIME SERIES" CALCULATIONS The "time series" method for estimating the increase in the anthropogenic inventory uses measurements of TC02 made at a certain point in time to develop a predictive equation based on a multiple linear regression of the observed TC02 and simultaneously measured parameters such as temperature, salinity, oxygen, and TA (or silicate). These empirical multiparameter relationships have been shown to hold over large spatial scales, and their use drastically reduces the complicating effects of natural variability in determining temporal trends [Brewer et al., 1995; Wallace, 1995; Brewer et al., 1997]. The TC02 residuals from such predictive equations can be compared directly with patterns of residuals evaluated using the same predictive equation with TA, oxygen, and hydrographic data collected at different times (e.g., over decadal intervals). Since the uptake of anthropogenic CO2 will increase the TC02 of the waters but will not directly affect the concentrations of the fit parameters, systematic changes in the magnitude and distribution of the TC02 residuals over time provide a direct estimate of the oceanic CO2 inventory change due to the uptake of anthropogenic CO2. The most comprehensive historical carbon data set for the Indian Ocean is from the GEOSECS expedition. By examining the WOCE data relative to that collected during the 1977-1978 GEOSECS Indian Ocean Survey, the increase in anthropogenic inventory over the last 18 years can be estimated. 2.2.1. GEOSECS FIT All of the GEOSECS data from the Indian Ocean (excluding Gulf of Aden and Red Sea regions) were fit with a single predictive equation as a function of potential temperature (9), salinity (S), apparent oxygen utilization (AOU), and TA. To minimize the influence of short-term temporal variability, only data from pressures greater than 200 dbars were included in the fit. Despite the large area covered, the GEOSECS TC02 values can be predicted from this equation to ± 5.2 µmol kg-1 (~ =0.992 and N = 1120). There is, however, a pattern in the residuals that correlates with observed hydrographic regions in the Indian Ocean (Figure 3). In an attempt to improve the fit, a categorical variable based on region was added to the regression. The categorical variable differs from the other continuous variables by the fact that it is either applied or not applied depending on whether the sample is located within the region. The regions were defined as follows: I, Arabian Sea (north of l0°N and west of 78°E); 2, North of 10°S (excluding Arabian Sea); 3, Chemical Front (21°S to 10°S); 4, Central Gyre (35°S to 21°S); and 5, Southern Ocean (south of 35°S) The addition of the regional variable resulted in a marginal improvement in the fit (~ =0.993 and (J =4.9 µmol kg-1) but more importantly, removed the regional bias in the predictive equation. The coefficients of the final fit are shown in Figure 4 along with a plot of the measured versus calculated TC02 values for all of the points used in the fit. The resulting equation was then used to generate TC02 values for each of the WOCE sample locations based on the measured temperature, salinity, oxygen, and TA values. The difference between the measured TC02 and the predicted TC02 reflects the CO2 increase in the time between the two cruises. For this work the difference is referred to as "excess CO2," FIGURE 2: Mean difference between deep water values of (a) TA and (b) TC02 for cruise intersections identified in Figure 1. Bars indicate one standard deviation. Dotted boxes indicate difference before adjustment (see explanation in text). FIGURE 3: Box and whiskers plot of residuals from a multiple linear regression of GEOSECS Indian Ocean data (pressure> 200 dbars) fit without the regional designator versus oceanographic region: TC02 = 706.5 + 7.7S - 6.689 + 0.513TA + 0.7257AOU. Solid boxes cover the range of ±1 standard deviation about the mean. White lines within the boxes indicate median values. The whiskers indicate the range of data within the 99% confidence interval. The bars outside the whiskers give the values of outliers in the data set. FIGURE 4: Plot of measured GEOSECS TC02 versus the calculated values. Solid line shows 1:1 relationship. The dashed lines indicate the 99% confidence interval for the fit. Text gives coefficients and related statistics. The column labeled "Pr(>|T|)" gives the probability that the T value in the previous column is larger than the T table value in a student T test. The residual method of estimating excess CO2 was applied to the water column below 200 dbars. The surface waters, however, are dominated by seasonal variability which can bias the residual calculations. The excess CO2 of the surface waters therefore was determined from the difference in the estimated annual mean TC02 concentrations between GEOSECS and WOCE. The annual mean TC02 concentration was calculated from TA and surface water ƒC02. The surface alkalinity was estimated from the gridded annual mean salinity and temperature values of Levitus et al. [1994] and Levitus and Boyer [1994] using a multiple linear fit of the WOCE/JGOFS surface (pressure < 60 dbars) TA data to the measured surface temperature and salinity. The 1978 and 1995 surface water jC02 concentrations were estimated from the annual mean atmospheric concentration for the 2 years. and the annual mean ∆pC02 values estimated from the full correction scheme of Takahashi et al. [1997]. The excess TC02 values between the surface and 200 dbars were estimated with a linear approximation between the surface and 200 dbars values for each 1° grid box. 2.2.2. DATA CONSISTENCY. One of the major concerns with the time series technique is the necessity of having two data sets that are consistent with each other. This consistency can be well documented for both TC02 and TA today through the use of certified reference materials (CRMs) supplied by A. Dickson of Scripps Institute of Oceanography (SIO). Since CRMs were not available at the time of GEOSECS. the only way to infer consistency with the WOCE data set is to assume the deep water carbon distributions have not changed since GEOSECS. The most reliable way to compare the two data sets is to examine the difference between the predicted TC02 and the measured TC02 (excess CO2) in deep waters. The basic assumption with this technique is that the correlation between the different hydrographic parameters in the deep waters does not change with time. Given the long residence time of the deep and bottom waters in the ocean. this should be a reasonable assumption. This technique has the advantage that it implicitly accounts for the possibility of real variability in hydrographic properties between the two expeditions which would not be taken into account by simply comparing carbon profiles. Examination of the excess CO2 values in waters that should be free of anthropogenic CO2 (pressures> 2000 dbars and containing no detectable chlorofluorocarbons) revealed that the GEOSECS values were 22.5 ±3 µmol kg-1 higher than the comparable WOCE measurements. This difference is comparable to the correction of 18 ± 7 µmol kg-1 noted by Weiss et al. [1983] to make the TC02 measurements consistent with the TA and discrete CO2 partial pressure measurements based on the Merbach et al. [1973] dissociation constants. Additional support for an adjustment of the original GEOSECS data comes from C. D. Keeling's shore-based analysis ofTC02 samples collected on both the GEOSECS and the WOCE/JGOFS expeditions. Weiss et al. [1983] point out that the shore-based analyses of Keeling were systematically smaller than the at-sea measurements by 16.5 ± 5 µmol kg-1 during GEOSECS. Similar comparisons between the WOCE/JGOFS at-sea measurements with Keeling's shore- based analyses indicate that the shore based samples are approximately 5 µmol kg-1 higher than the at sea values (P. Guenther. personal communication. 1998). Together. the GEOSECS-Keeling-WOCE/JGOFS combination suggests an offset of 21.5 µmol kg-1 between GEOSECS and WOCE/JGOFS at-sea measurements. It is also important to note that there is no indication of a depth or concentration dependent correction for the GEOSECS data. The shore-based comparison. based only on samples collected at the surface. is within I µmol kg-1 of the deep comparison described above. On the basis of these results a constant correction of the -22.5 µmol kg-1 was applied to the GEOSECS TC02 values to improve the consistency of the two data sets. Ideally. the data used in the time series calculations would cover the same geographic region with as much of a time difference as possible. The trade- off. however. is that the quality and spatial coverage of the older data sets is generally very limited. Given the relatively small area of overlap between the WOCE/JGOFS and INDIGO data sets and the shorter time difference between cruises (9 years versus 18 years for WOCE - GEOSECS). the time series analysis was limited to a comparison between WOCE/JGOFS and GEOSECS in the main Indian Ocean basin. 2.2.3. EVALUATION OF ERRORS An estimate of the random errors associated with the excess CO2 calculation can be made with a simple propagation of errors based on the fit to the GEOSECS data and the estimated precision of the WOCE/JGOFS data. With a standard deviation of 4.9 µmol kg-1 for the GEOSECS fit and an estimated long-term precision of ±2 µmol kg-1 in the WOCE/JGOFS TC02 values the excess CO2 error is estimated to be approximately ±5 µmol kg-1. This value compares well with the standard deviation of 3.5 µmol kg-1 for the excess CO2 below the maximum anthropogenic CO2 penetration depth (pressure> 1500 dbars). Systematic errors with this technique are very difficult to evaluate. The largest potential systematic error is probably associated with the surface water estimates. Because the same ∆pC02 value is used to estimate the TC02 for both years. the excess CO2 (1995 TC02 - 1978 TC02) is not very sensitive to potential errors associated with the actual ∆pC02 values used. The surface estimate is sensitive. however. to the assumption that the ∆pC02 has not changed over time (i.e.. that the surface ocean increase has kept pace with the atmospheric increase). It is not likely that the surface ocean has increased at a faster rate than the atmosphere. but it is conceivable that the rate is slower. The current assumption results in a total inventory of 0.8 Pg C in the surface layer. If the surface ocean were increasing at half the rate of the atmosphere. the systematic bias in the final inventory would be around 0.4 Pg C. Below the surface layer the most likely systematic error would result from the uncertainty in fitting the GEOSECS data. Systematic errors associated with calibration differences between cruises are potentially quite large. but the analysis and subsequent correction given in section 2.2.2 should remove these biases. The estimated uncertainty for the GEOSECS adjustment was ±3 µmol kg-1. If this value is integrated for the area north of 35°S between 200 m and the average penetration depth of the excess CO2 (~800 m). the potential error would be ±0.9 Pg C. Propagating the errors for the surface and deeper layers gives an estimated error of approximately ±1 Pg C in the total excess CO2 inventory. Clearly, there are other ways of estimating the potential errors in these calculations. but we feel that this is a reasonable estimate based on the available data. 2.3. ∆C* CALCULATIONS Gruber et al. [1996] developed a method to estimate the total anthropogenic CO2 inventory which has accumulated in the water column since pre-industrial times. Although the details of the calculation are thoroughly discussed by Gruber et al. the basic concept of the calculation can be expressed in terms of the following equation: C(anth)(µmol/kg) = C(m)-∆C(bio)-C(280)-∆C(dis) (1) where C(anth) anthropogenic carbon concentration; C(m) measured total carbon concentration; ∆C(bio) change in TC02 as a result of biological activity; C(280) TC02 of waters in equilibrium with an atmospheric CO2 concentration of 280 µatm; ∆C(dis) air-sea difference in CO2 concentration expressed in µmol kg-1 of TC02. The Gruber et al. technique employs a new quasi-conservative tracer ∆C*, which is defined as the difference between the measured TC02 concentration, corrected for biology, and the concentration these waters would have at the surface in equilibrium with a pre-industrial atmosphere (i.e., ∆C* = C(m) - ∆C(bio) - C(280)). Rearranging (I) shows that ∆C* reflects both the anthropogenic signal and the air-sea CO2 difference (i.e., ∆C* = C(anth) + ∆C(dis)). The airsea disequilibrium component can then be discriminated from the anthropogenic signal using either information about the water age (e.g., from transient tracers such as CFCs or 3H-3He) or the distribution of ∆C* in regions not affected by the anthropogenic transient. The details of this technique will not be covered here except as necessary to explain small modifications that were necessary for use with the WOCE Indian Ocean data set. 2.3.1. PREFORMED ALKALINITY EQUATION The first modification to the Gruber et al. [1996] technique involved a recalculation of the preformed alkalinity equation. The preformed alkalinity (Alk^0) of a subsurface water parcel is an estimate of the alkalinity that the water had when it was last at the surface. This value is necessary to determine the equilibrium concentration (C(280)) of the waters. Gruber et al. generated a single global equation for estimating Alk^0 from salinity and the conservative tracer "PO" (PO = 02+l70*P) [Broecker, 1974] based on the data collected during GEOSECS, South Atlantic Ventilation Experiment, Transient Tracers in the Ocean/North Atlantic Study and Transient Tracers in the Ocean/ Tropical Atlantic Study. Given the limited representation of the Indian Ocean in these data and the improved quality of today's measurements, the Gruber et al. fit was examined for a possible bias with respect to the WOCE/JGOFS results. Alk^0 values calculated from the Gruber et al. equation were found to be, on average, 7 ±12 µmol kg-1 lower than the WOCE/JGOFS measured surface alkalinity values. Rather than making assumptions about which parameters would provide the best fit to the surface alkalinity data, several possible parameters were tested based on previously noted correlations. Although salinity has been shown to generally correlate very strongly with surface alkalinity [Brewer et al., 1986; Millero et al., 1998b], some areas, such as the high-latitude regions, require additional parameters to fit regional changes in alkalinity. Some investigators have used temperature as an additional variable [e.g., Chen and Pytkowicz, 1979; Chen, 1990; Millero et al., 1998b]. Others, such as Gruber et al. [1996], have used other conservative tracers to compensate for the regional differences. The best fit for the WOCE/JGOFS, INDIGO, and CIVA Indian Ocean data, with pressures less than 60 dbars, is given by (2): Alk^0 = 378.1+55.22 x S+0.0716 x PO-1.236 x θ (2) Alk^0 has units of µmol kg-1 when salinity (S) is on the practical salinity scale, PO is in µmol kg-1, and potential temperature (θ) is in degrees Celsius. The standard error in the new Alk^0 estimate is ±8.0 µmol kg-1 based on 2250 data points. A standard ANOVA analysis of the fit shows that all four terms are highly significant (Table 1). Reevaluating the Alk^0 equation not only removed the 7 µmol kg-1 offset of Gruber's equation but also resulted in a 35% reduction in the uncertainty. TABLE 1: Results From ANOVA Analysis of Alk^0 Fit. ____________________________________________________ Coefficient Standard T Value Pr(>|T|) Error ----------- -------- -------- -------- Intercept 378.1 8.9 42.2715 0.0000 Salinity 55.22 0.23 235.0369 0.0000 PO 0.0716 0.0041 17.4693 0.0000 Theta -1.236 0.061 -20.3697 0.0000 ____________________________________________________ The column labeled "Pr(>rr1)" gives the probability that the T value in the previous column is larger than the T table value in a student T test. Alk^0 is preformed alkalinity. an estimate of the alka- linity of a parcel of subsurface water when it was last at the surface. 2.3.2. DENITRIFICATION CORRECTION A second modification to the original ∆C* technique was necessary to properly account for the anoxic regions in the northern Indian Ocean. The C(bio) term in (1) assumes that the remineralization of carbon in the interior of the ocean occurs in proportion to the oxygen uptake based on a standard Redfield type stoichiometry. The ratios used for these calculations were based on the global estimates of Anderson and Sarmiento [1994]. Gruber et al. [1996] demonstrated that the errors in the ∆C* calculation due to uncertainties in the C:O stoichiometric ratio only become significant for AOU values greater than 80 µmol kg-1. Given that most of the anthropogenic CO2 is found in relatively shallow waters with low AOU, this error, on average, is small. For some regions of the Arabian Sea, however, oxygen depletion can be quite extensive at relatively shallow depths [Sen Gupta et al., 1976; Deuser et al., 1978; Naqvi and Sen Gupta, 1985]. In areas where the waters become anoxic, denitrification can significantly alter the dissolved carbon to oxygen ratio [Naqvi and Sen Gupta, 1985; Anderson and Dyrssen, 1994; Gruber and Sarmiento, 1997]. The dissolved carbon generated by denitrification shows up as high ∆C* values as demonstrated at the northern end of the section in Figure 5a. The distribution of ∆C* values along the density surface σθ = 26.9- 27.0 shows maximum values at both the northern and southern ends of the section. One would expect the uptake of anthropogenic CO2 to generate the highest values close to the outcrop region in the south, but this surface does not outcrop in the north. Following the methods of Gruber and Sarmiento [1997], the denitrification signal can be estimated using the N* tracer. N* is a quasi-conservative tracer which can be used to identify nitrogen (N) excess or deficits relative to phosphorus (P). Using the global equation of Gruber and Sarmiento [1997], N* is defined as N*(µmol/kg) = 0.87(N - 16P + 2.90) (3) Figure 5b shows the magnitude of the denitrification signal along the σθ = 26.9-27.0 surface. The N* values were converted from nitrogen units to µmol C kg-1 based on a denitrification carbon to nitrogen ratio of 106:-104 [Gruber and Sarmiento, 1997]. Negative values reflect nitrogen fixation, while positive values indicate denitrification. As expected, the values of N* are essentially zero in the main Indian Ocean basin but show a strong denitrification signal at middepths in the Arabian Sea. The low N* values at the north end of this surface (Figure 5b) are from the Bay of Bengal and show little or no denitrification in this region. Subtracting a denitrification correction term from the original ∆C* equation lowers the high ∆C* values at the northern end of the section leaving the expected maximum near the outcrop region (Figure 5c). The final definition for ∆C* as used in this work is given by (4) ∆C* = TCO2^meas - TCO2^(S,T,Alk^0,280) -(117/-170)(O2-O2^(sat)) -(1/2)(TA-ALK^0+(16/-170))O2-O2^(sat)) -(I06/-104)N* (4) where TC02(meas), TA, and O2 are the measured concentrations for a given water sample in µmol kg-1. Alk^0 is the preformed alkalinity value as described in section 2.3.1. 02^(sat) is the calculated oxygen saturation value that the waters would have if they were adiabatically raised to the surface. TCO2^(S,T,Alk^0,280) is the TC02 value the waters would have at the surface with a TA value equal to Alk^0 and ƒC02 value of 280 µatm. 2.3.3. ESTIMATION OF AIR-SEA DISEQUILIBRIUM To isolate the anthropogenic CO2 component from ∆C*, the air-sea disequilibrium values (∆C(dis)) must be determined. Gruber et al. [1996] described two techniques for estimating these values on density surfaces. For deeper density surfaces one can assume that the waters far away from the outcrop region are free from anthropogenic CO2. The mean ∆C* values in these regions therefore reflect only the disequilibrium value. For shallower surfaces the air-sea disequilibrium can be inferred from the ∆C*I tracer. ∆C*(t) is the difference between C* and the concentration the waters would have in equilibrium with the atmosphere at the time they were last at the surface. The time since the waters were in contact with the surface is estimated from CFC-12 age (t) and the atmospheric CO2 concentration history as a function of time (ƒC02{t(sample)-t}). The atmospheric CO2 time history from 1750 through 1996 was determined from a spline fit to ice core and measured atmospheric values [Neftel et al., 1994; Keeling and Whorf, 1996]. The CFC-12-based ages were determined following the technique described by Warner et al. [1996]. The apparent age of the water is determined by matching the CFC-12 partial pressure (pCFC-12) of the waters with the atmospheric CFC- 12 concentration history (procedures and atmospheric time history provided by J. Bullister). Although CFCs do not give a perfect representation of the true calendar age of the waters, Doney et al. [1997] have shown that the CFC-12 and 3H-3He ages in the North Atlantic agree within 1.7 years for ages less than 30 years. Gruber [1998] successfully used both CFC and 3H-3He ages for his disequilibrium calculations in the Atlantic and has thoroughly discussed the assumptions and caveats associated with these techniques. The disequilibrium values on shallow density surfaces presented here were calculated using CFC-12 ages modified from the ∆C*(t) equation of Gruber [1998] to include the denitrification correction: ∆C*(t) = TCO2^meas - TCO2^(S,T,Alk^0,ƒC02{t(sample)-t}) -(117/-170)(O2-O2^(sat)) -(1/2)(TA-ALK^0+(16/-170))O2-O2^(sat)) -(I06/-104)N* (5) where TCO2^(S,T,Alk^0,ƒC02{t(sample)-t}) is the TC02 the waters would have at the surface with a TA value of Alk^0 and ƒC02 value in equilibrium with the atmospheric CO2 concentration at the time the waters were last at the surface (date of sample collection minus CFC age). The CFC age method was used for waters with densities less than σθ = 27.25 and CFC-12 ages less than 40 years. The anthropogenic CO2 of the waters with pressures less than 150 dbars or densities less than σθ = 25.95 was determined by subtracting the ∆C*(t) value estimated at each sample location from the corresponding ∆C* value. Given that the Indian Ocean does not extend into the high northern latitudes, the major outcrop region for Indian Ocean waters below the mixed layer is toward the south. Although other tracers might be used to identify multiple end-members, the CFC-12 ages on each density surface get steadily older toward the north, and the ∆C*(t) values are reasonably constant (see diamonds in Figure 6). This suggests that most of the water in the Indian Ocean is derived from the south or, at least in terms of the air-sea disequilibria, cannot be distinguished from other sources. The ∆C(dis) term for the main Indian Ocean basin therefore was determined from a mean ∆C*(t) value on each surface. The mean ∆C(dis) terms were then subtracted from the individual ∆C* values to determine the anthropogenic component. Table 2 summarizes the ∆C(dis) values for the density surfaces estimated exclusively from the ∆C*(t) method. One major exception to the southern source waters is observed in the Arabian Sea. Although none of the surfaces with σθ values greater than 26.0 outcrop in the Arabian Sea, a number of higher density surfaces do outcrop in the Red Sea and Persian Gulf. These outcrops could provide pathways for the introduction of CFCs and anthropogenic CO2 into the northern Arabian Sea and could reset the disequilibria term. Wyrtki [1973] noted that the Red Sea and Persian Gulf waters mix in the Arabian Sea to form the high-salinity North Indian Intermediate Water (NIIW). The ∆C*(T) values in the Arabian Sea do vary significantly and generally have a strong correlation with salinity. The CFC-12 ages also begin to get younger toward the northern end of the Arabian Sea. These high salinity waters appear to have a higher disequilibria term than the lower-salinity waters that make up the majority of the Indian Ocean intermediate waters. To account for this phenomenon, the Arabian Sea waters (north of 5°N and west of 78°E) were isolated, and the ∆C*(t) values were fit against salinity with a linear regression. Thus this region was treated as a two-end-member mixing scenario between the high salinity NIIW and the lower-salinity waters of the main Indian Ocean basin. The ∆C(dis) values in this region were determined based on the relative contributions of the two end-members using salinity as a conservative tracer. The coefficients for the Arabian Sea fits are given in Table 2. The difference between the high salinity and lower-salinity disequilibria generally decreased as densities increased (note decreasing slope values in Table 2) to the point where the Arabian Sea disequilibria values were no longer distinguishable from the main Indian Ocean basin values. The additional terms were dropped for surfaces where the two end member mixing terms resulted in values within the error of the basin-wide mean (Table 2). As stated previously, the disequilibria term for the deeper, CFC free surfaces was determined directly from the mean ∆C* value of each density interval. Careful examination of the extent of CFC penetration along the density surface was used to limit data used in determining the ∆C(dis) term. Only regions where CFC concentrations were below a reasonable blank (0.005 pmol kg-1) were considered. The ∆C(dis) values determined using this method are summarized in the lower half of Table 3 (σθ > 27.5). FIGURE 5: ∆C* values for data on the 26.9 - 27.0 σθ surface: (a) calculated without denitrification, (b) denitri- fication signal put in terms of ∆C*, (c) with denitrification correction (i.e., data in Figure 5a minus the data in Figure 5b). Determination of the ∆C(dis) values for either shallow or deep surfaces is relatively straightforward using the techniques mentioned above. It is not straightforward, however, to estimate the ∆C(dis) values for intermediate levels where the CFC ages are relatively old and may be significantly influenced by mixing and yet the waters could have enough anthropogenic CO2 to influence the estimates based on ∆C*. The effect of using the ∆C* technique in waters that actually have anthropogenic CO2 would be to overestimate the ∆C(dis) term and thus underestimate the anthropogenic CO2, The effect of mixing on the CFC ages, however, generally results in an underestimation of the CFC age which would lead to an underestimation of the ∆C(dis) term and an overestimation of the anthropogenic CO2, The CFC age technique has additional problems in waters with σθ values greater than 27.25, because the waters with the younger ages are all found in the very high latitudes of the Southern Ocean and generally are not directly ventilated in these regions. Therefore the basic assumption that the ∆C(dis) term can be determined by following the density level to its outcrop and examining the younger waters there is not valid. TABLE 2: Values of ∆C(dis) Determined on Potential Density (σθ) Intervals _______________________________________________________________________ Potential Main Basin Main Arabian Arabian Arabian Density Mean (SDM) Basin # Intercept Slope # of Range of Points (SD) (SD) Points ----------- ------------ --------- ---------- -------- ------- 25.95-26.05 -1.3(±0.88) 56 -740(±92) 21.3(±3) 12 26.05-26.15 -0.7(±1.21) 42 -745(±130) 21.4(±4) 12 26.15-26.25 -3.4(±0.65) 63 -699(±76) 20.0(±2) 11 26.25-26.35 -4.8(±0.62) 61 -516(±90) 14.8(±3) 12 26.35-26.45 -5.6(±0.48) 83 -316(±84) 9.1(±2) 20 26.45-26.55 -7.1(±0.34) 103 -558(±87) 15.9(±2) 21 26.55-26.65 -7.2(±0.32) 123 -512(±53) 14.5(±I) 28 26.65-26.75 -8.9(±0.27) 152 -397(±52) 11.2(±I) 34 26.75-26.85 -9.1(±0.23) 254 -428(±66) 12.0(±2) 28 26.85-26.95 -11.2(±0.31) 209 -285(±115) 7.9(±3) 6 26.95-27.00 -12.2(±0.35) 104 27.00-27.05 -13.8(±0.48) 92 27.05-27.10 -15.2(±0.4O) 90 27.10-27.15 -16.3(±0.47) 84 27.15-27.20 -17.1(±0.51) 89 27.20-27.25 -19.5(±0.56) 74 _______________________________________________________________________ Standard deviations (SD) are given for the slope and intercept terms for the Arabian Sea data. Standard deviation of the mean (SDM, i.e., standard deviation weighted by the number of individual determinations) is given for each main basin estimate. Values of ∆C(dis) are given in µmol kg-1. Dashes indicate value not determined. TABLE 3: Values of ∆C(dis) Determined on Potential Density (σθ) Intervals _________________________________________________________________________ Potential Mean ∆C* # of Mean ∆C*l # of Final Mean Density (SDM) Points (SDM) Points ∆Cdi5(SDM) Range ----------- ------------ ------ ------------ ------ ------------ 27.25-27.30 -2.3(±0.45) 42 -19.7(±0.98) 22 -8.3(±1.l3) 27.30-27.35 -4.0(±0.49) 45 -21.0(±0.84) 19 -9.1(±1.06) 27.35-27.40 -5.3(±0.44) 72 -22.5(±1.25) 7 -6.8(±0.69) 27.40-27.45 -7.1(±0.26) 92 -23.5(±0.83) 10 -8.7(±0.54) 27.45-27.50 -7.9(±0.30) 98 -25.0(±1.65) 7 -9.0(±0.51) 27.50-27.55 -9.3(±0.28) 93 -9.3(±0.28) 27.55-27.60 -10.7(±0.28) 92 -10.7(±0.28) 27.60-27.65 -11.3(±0.34) 125 -11.3(±0.34) 27.65-27.70 -13.0(±0.36) 127 -13.0(±0.36) 27.70-27.75 -14.8(±0.30) 184 -14.8(±0.30) 27.75-27.80 -15.3(±0.24) 349 -15.3(±0.24) >27.80 -18.6(±0.15) 629 -18.6(±0.15) _________________________________________________________________________ Standard deviation of the mean given in brackets (SDM, i.e., standard deviation weighted by the number of individual determinations). Values of ∆C(dis) are given in µmol kg-l. Dashes indicate value not determined. As a general rule, the errors associated with the CFC age technique increase at higher density levels, and the errors associated with the ∆C* technique decrease at higher density levels. To minimize the errors in the final ∆C(dis) determination, waters with σθ values between 27.25 and 27.5 were evaluated using a combination of the two methods mentioned above. The 27.25 cut in the CFC age technique was chosen because this density corresponds with the core of the Antarctic Intermediate water and also generally the highest- density water that outcrops in this region [Wirtki, 1973; Levitus and Boyer, 1994; Levitus et al., 1994]. To help ensure that the ∆C(dis) values were determined on waters moving into the main Indian Ocean basin, mean ∆C*(t) values were only estimated from samples north of 35°S with CFC-12 ages less than 40 years. Mean ∆C* values were also determined on the same density surfaces for samples where CFCs were measured, but concentrations were below 0.005 pmol kg-1. The final mean value used for the ∆C(dis) correction on each surface was determined from the mean of the combined individual estimates from each method (Table 3). Examination of the individual and combined means in Table 3 indicates that there is a sizeable spread in the estimates from the two techniques in the overlap region. This difference is maximized since these density levels are pushing the limits of both techniques, and the errors in both estimates serve to increase this difference. Since the number of points available from the CFC age technique generally decreased at greater density levels and the number of points from the ∆C* technique generally increased at greater density levels, the mean becomes progressively more heavily weighted toward the ∆C* technique as the density levels increased. Although this is not the ideal solution, we believe that this minimizes the potential errors as much as possible. The technique used to estimate final ∆C(dis) values in this region could systematically bias the anthropogenic CO2 inventory estimates. The magnitude of this potential error on the final inventory was estimated to be approximately ±1.8 Pg C by integrating the difference between the two methods over the effected water volume. This estimate represents a maximum potential error since the known limitations of each method work to increase the differences in ∆C(dis). 2.3.4. TIME ADJUSTMENT FOR INDIGO DATA One difficulty with combining data from different cruises for a time- dependent calculation like the anthropogenic CO2 inventory is the issue of getting the data sets referenced to a common time. One of the advantages of the WOCE/JGOFS Indian Ocean survey data is the fact that all of the samples were collected in a little over a year's time. In terms of the CO2 inventory this is essentially a synoptic data set. The couple of years between the CIVA-1 cruise and the WOCE/JGOFS data are also not distinguishable in terms of the anthropogenic increase. The INDIGO data, however, were collected 8-10 years before the WOCE/JGOFS data set and must be adjusted to reflect the anthropogenic uptake during that time. Unfortunately, any correction of this sort can have large errors and potentially bias the results. This problem must be weighed against the errors of ignoring the time difference between cruises or omitting these data entirely. The decision to correct the INDIGO data was based on two factors. First, analysis of the change in anthropogenic inventory between GEOSECS and WOCE (discussed below) indicated that a significant fraction of the total anthropogenic uptake has occurred in the past 2 decades. Second, careful examination of objective maps of anthropogenic CO2 made prior to the INDIGO correction showed obvious, anomalously low concentrations in the regions strongly dependent on the INDIGO data. Two different adjustment functions were made depending on whether the stations were located in the main Indian Ocean basin or in the Southern Ocean. North of 30°S, where portions of the INDIGO data were located relatively near WOCE stations, a crossover comparison of the INDIGO anthropogenic CO2 concentrations as a function of density was made with the WOCE/JGOFS data in that region. The difference between the two data sets was evaluated at σθ intervals of 0.05 from the surface to σθ = 27.5 and added to the INDIGO data. This correction ranged from approximately 12 µmol kg-1 at the surface down to zero at 27.5. South of 30°S, there were very few WOCE or CIVA-1 stations close enough for a proper crossover comparison. It was clear from the northern data, however, that some correction was necessary. Given that the isolines for most properties in the Southern Ocean run east-west, we decided to correct the southern INDIGO data based on a crossover comparison with all results from CIVA-1 and WOCE cruises in that region. The average adjustment for the southern stations was approximately 11 µmol kg-l over the same density range. The magnitude of the corrections in both regions is consistent with the expected increase over the time period between cruises. 2.3.5. EVALUATION OF ERRORS Error evaluation is much more difficult for the ∆C* method than for the time series approach because of potential systematic errors associated with some of the parameters (Le., the biological correction). The random errors associated with the anthropogenic CO2 can be determined by propagating through the precision of the various measurements required for the calculation of (4). {σ(C(anth))}^2 = {σ(C)}^2 + {σ(C(eq))}^2 + {(-R(CO) - 0.5R(NO))σ(O(2))}^2 + {(R(CO) + 0.5R(NO))σ(O(2[sat]))}^2 ∂C(eq) + {-0.5σ(TA)}^2 + {(- ------ + 0.5)σ(Alk^0)}^2 ∂TA + {0.8667σ(N)}^2 + +{13.867σ(P)}^2 N-16P+2.9 + {0.8667(-P - --------- )σ(R(N:P[nitr]))}^2 120 + {-0.00111(N - 16P + 2.9)σ(R(N:P[denitr]))}^2 - {σ(∆C(dis))}^2 (6) where σ(C) = 2 µmol kg-1 ; σ(C(eq)) = 4 µmol kg-1 ; σ(O(2)) = 1 µmol kg-1 ; σ(O(2[sat])) = 4 µmol kg-1 ; σ(TA) = 4 µmol kg-1 ; ∂C(eq) ------- = 0.842 ; ∂TA σ(Alk^0) = 7.8 µmol kg-1 ; σ(N) = 0.2 µmol kg-1 ; σ(P) = 0.02 µmol kg-1 ; σ(R(N:P[nitr])) = 0.25 ; σ(R(N:P[denitr])) = 15 The equation for the random error analysis is adapted from Gruber et al. [1996] (excluding those terms that involve the C:O Redfield error) with additional terms for the error propagation of the N* correction [Gruber and Sarmiento, 1997]. The terms involving the C:O are evaluated separately below because the random errors cannot be isolated from potential systematic errors. The sigma values used in (6) were either taken from the appropriate WOCE cruise reports or from previously determined estimates of Gruber et al. [1996] and Gruber and Sarmiento [1997]. The error in the ∆C(dis) term is taken from the average value for the standard deviation of the mean for the examined surfaces (σ(∆C(dis)) = 0.5 µmol kg-1). The formulation given in (6) results in an estimated error of 6.1 µmol kg-1. This estimate is larger than the standard deviation of the ∆C* values below the deepest anthropogenic CO2 penetration depth (±2.8 µmol kg-1 for pressure > 2000 dbars) suggesting that the propagated errors may be a maximum estimate of the random variability. The potential systematic errors associated with the anthropogenic CO2 calculation are much more difficult to evaluate. The random error estimate above includes all terms except those associated with the C:O biological correction. Although other terms involving N:O and N:P corrections potentially have systematic offsets associated with errors in the ratio estimates, the only potentially significant errors involve the C:O corrections [Gruber et al., 1996; Gruber, 1998]. There is evidence, however, that the Anderson and Sarmiento [1994] stoichiometric ratios must be reasonably close to the actual remineralization ratios observed in the Indian Ocean. Figure 6 is a plot of ∆C*t based on CFC- 12 ages for the density interval from σθ = 27.1 to σθ = 27.15. The diamonds are the values calculated from (5). These values represent the preserved air- sea disequilibrium value for the past 40 years and should be constant if the air-sea disequilibrium has not changed over time (Le., that the surface ocean CO2 is increasing at the same rate at the atmosphere). A linear regression of the diamonds in Figure 6 yields a slope that is not significantly different from zero. The circles and pluses are the ∆C*t values one would get by using a C:O ratio of -0.60 and -0.78 in (5), respectively. These C:O values represent one standard deviation from the Anderson and Sarmiento [1994] mean value of 0.69. The -0.60 ratio results in values with a significant positive slope. This slope would imply that the surface ocean CO2 is increasing much slower than the atmospheric increase. While this is possible, the -0.60 ratio is much larger than historical Redfield estimates and would be very difficult to justify. The -0.78 ratio is more typical of historical estimates but results in a significant negative slope in the ∆C*t values with time. A negative slope would imply that carbon is accumulating in the ocean faster than the atmosphere. Neither of these scenarios seems very likely. The fact that none of the ∆C*t values on the examined surfaces exhibit a statistically significant slope suggests that the C:O value of -0.69 does accurately represent the remineralization ratio for these waters and supports the methodology of taking a mean value of ∆C*t on these density surfaces. FIGURE 6: Plot of ∆C*t based on CFC-12 ages for the density interval from σθ =27.1 to 27.15 versus CFC-12 age. The diamonds were calculated using the Anderson and Sarmiento [1994] c:o (-0.69). The circles and pluses were calculated from C:O of -0.60 and -0.78, respectively. Lines and text give results from a linear regression of the three sets of data. A sensitivity study was also used to evaluate the potential error associated with an incorrect C:O value. Two additional estimates of anthropogenic CO2 were determined using the -0.60 and -0.78 C:O values. Since the C:O correction applies to both ∆C* and the ∆C*(t) terms, the disequilibrium values were reevaluated in the same manner as described above. The range of anthropogenic values from these three estimates varied as a function of apparent oxygen utilization (AOU) from 0.0 to 22 with an average difference of only 4.2 µmol kg-1. Because the C:O correction affects both the ∆C* and ∆C*(t) terms together, much of the systematic error in the final anthropogenic estimate (∆C*-∆C*(t)) cancels out. 2.4. INVENTORY ESTIMATES Basin-wide anthropogenic and excess CO2 concentrations (WOCE/JGOFS - GEOSECS) were evaluated on a 1° grid at 100 m intervals between the surface and 2600 m using the objective mapping techniques of Sarmiento et al. [1982]. Total anthropogenic CO2 was mapped over an area from 20° to 120°E and 70°S to 30°N (excluding areas of land, the Red Sea, the Persian Gulf, and the South China Sea). Because the WOCE/JGOFS data set did not cover much of the Southern Ocean, the excess CO2 maps were limited to the area north of 35°S. The values at each level were multiplied by the volume of water in the 100 m slab and summed to generate the total anthropogenic or excess CO2 inventory. The method of integrating mapped surfaces compared very well with the technique of vertically integrating each station and mapping the station integrals. It is extremely difficult to evaluate a reasonable estimate of the potential errors associated with the inventory estimates. A simple propagation of errors implies that the random errors associated with any individual anthropogenic estimate is approximately ±6.1 µmol kg-1, but these errors should essentially cancel out for an integrated inventory based on nearly 25,000 individual estimates. Systematic errors have by far the largest impact on the inventory estimates. Potential errors as large as ±1.8 Pg C have been estimated for the ∆C(dis) term. Sensitivity studies with the C:O variations give a range of total inventory estimates of ±2.5 Pg C. Other systematic errors could also be generated from the denitrification term, the terms involving N:0, the time correction for the INDIGO data, and the mapping routines used in the inventory estimates. The magnitude of these errors is believed to be much smaller than the uncertainty in either the C:O correction or the ∆C(dis) determination. Propagation of the two estimated uncertainties gives an overall error of approximately ±3 Pg C for the total inventory. An error of roughly 15% is comparable to previous error estimates using this technique [Gruber et al., 1996; Gruber, 1998]. Errors for regional inventories are assumed to scale to the total. 3. RESULTS AND DISCUSSION The excess CO2 concentrations for the Indian Ocean range from 0 to 25 µmol kg-1. The most prominent feature in the excess CO2distribution, as shown with representative sections in the eastern and western Indian Ocean (Figure 7), is the maximum in concentrations at midlatitudes (~40°S). This maximum is coincident with the relatively strong gradient in surface density associated with the Subtropical Convergence and the transition from the high salinity subtropical gyre waters to the low-salinity Antarctic waters. The outcropping of these density surfaces and subsequent sinking of surface waters provides a pathway for excess CO2 to enter the interior of the ocean. Relatively high excess CO2 concentrations can also be observed at the very northern end of the western section (Figure 7a). Although not readily evident from this section, the distribution of concentration gradients indicates that excess CO2 is entering the northern Indian Ocean from the Persian Gulf and Red Sea regions. This is likely to result from the outcropping of density surfaces in these areas which are not ventilated in the main Indian Ocean basin. The implied Red Sea and Persian Gulf sources of CO2 are consistent with uptake estimates of anthropogenic CO2 in these areas as observed by Papaud and Poisson [1986]. The third major feature observed in the excess CO2 distribution is a dramatic shoaling of the excess CO2 isolines south of approximately 40°S. Poisson and Chen [1987] attributed the low anthropogenic CO2 concentrations in Antarctic Bottom Water to a combination of the pack sea ice blocking air-sea gas exchange and the upwelling of old Weddell Deep Water. This explanation is consistent with the observed excess CO2 distributions in this study. The general features observed with excess CO2 are also observed in the anthropogenic CO2 distribution (Figure 8). The range of values, however, extends up to 55 µmol kg-1. The maximum depth of the 5 µmol kg-1 contour is approximately 1300 m at around 40°S, only 200 m deeper than the maximum depth of the 5 µmol kg-1 contour of excess CO2, The similarity in maximum penetration depth between the 200 year and the 18 year anthropogenic CO2 accumulation, together with the wide range of depths covered by the 5 µmol kg-1 isoline, indicates that the primary pathway for CO2 to enter the ocean's interior is from movement along isopycnals, not simple diffusion or cross isopycnal mixing from the surface. The 1300 m penetration results from the downwarping of the isopycnals in the region of the Subtropical Convergence. Likewise, the low anthropogenic CO2 concentrations in the high-latitude Southern Ocean result from the compression and shoaling of isopycnal surfaces in that region. Although the complex oceanography of the Southern Ocean may call into question some of the assumptions regarding mixing and nutrient uptake ratios with these techniques, both the time series excess CO2 and the ∆C* anthropogenic CO2calculations clearly indicate that the anthropogenic CO2 concentrations south of approximately 50°S are relatively small. The distribution of anthropogenic CO2 determined in this study is similar to the distribution presented by Chen and Chen [1989] based on GEOSECS and INDIGO data. Although the penetration depth at 40°S was slightly deeper than observed with this study (1400-1600 m for the 5 µmol kg-1 isoline), Chen and Chen also observed a significant shoaling of the anthropogenic CO2 isolines toward the south. They suggest that anthropogenic CO2 has only penetrated a few hundred meters into the high-latitude (>50°S) Southern Ocean. There has been debate in the literature over recent years as to the importance of the Southern Ocean as a sink for anthropogenic CO2 [e.g., Sarmiento and Sundquist, 1992; Keeling et al., 1989; Tans et al., 1990]. Most of the recent data-based estimates, however, indicate a relatively small Southern Ocean sink [Poisson and Chen, 1987; Murphy et al., 1991; Gruber, 1998; this study]. The lack of observed anthropogenic CO2 in the Southern Ocean is also qualitatively consistent with ∆14C estimates which show no measurable storage of bomb 14C in the Southern Ocean since GEOSECS [Leboucher et al., 1998; R. Key, unpublished data, 1998]. Recent studies by Bullister et al. [1998], which show evidence of deep CFC penetration in the Southern Ocean, may appear to contradict these low anthropogenic CO2 estimates, but we believe it is further evidence that one must be careful when inferring anthropogenic carbon distributions from other tracers. One possible explanation of this apparent discrepancy may be the CFC equilibration rate of days which is significantly faster than the CO2 equilibration time of months [e.g., England, 1995; Warner and Weiss, 1985; Tans et al., 1990]. This can become an issue in the Southern Ocean where upwelling and convection may allow the CFCs to equilibrate to a greater extent than the CO2, Again, we acknowledge the limitations of the methods used in the Southern Ocean, and it is possible that the apparent discrepancy in the CFC penetration versus the CO2 penetration may also be an issue of detection limits. With a detection limit that is approximately 6 µmol kg-1, it is not possible to say with this technique that the concentration of anthropogenic CO2 below 500 m at 60°S is zero. However, we can say with some confidence that the concentration is not 10 µmol kg-1 or greater. Since there is no natural oceanic source of CFCs and these compounds are not biologically utilized, the ability to detect them is much greater. If mixing has diluted the anthropogenic signal to concentrations just below detection limits, it is possible that carbon measurement based techniques would underestimate the Southern Ocean sink. FIGURE 7: Sections of excess CO2 along (a) -57°E and (b) -92°E. Dots indicate sample locations used in sections. Note that I6S data along 30°E were brought into the line of section for contours south of 40°S in Figure 7a. The total anthropogenic CO2 inventory for the main Indian Ocean basin (north of 35°S) was 13.6±2 Pg C in 1995. The increase in CO2 inventory since GEOSECS was 4.1±1 Pg C for the same area. This represents a nearly 30% increase in the past 18 years relative to the total accumulation since pre-industrial times. The relative oceanic increase is very similar to the 31% increase observed in atmospheric concentrations over the same time period [Keeling and Whorf, 1996]. This similarity suggests that the oceans, at least for now, are keeping pace with the rise in atmospheric CO2, Approximately 6.7±1 Pg C are stored in the Indian sector of the Southern Ocean giving a total Indian Ocean inventory (between 20° and 120°E) of 20.3±3 Pg C in 1995. To put these results in a global perspective, the total inventory for the Indian Ocean is only half that of the Atlantic (40±6 Pg C [Gruber, 1998]), but it contains an ocean volume that is nearly 80% of the Atlantic. The main difference between the two oceans, of course, is that the Indian Ocean does not have the high northern latitude sink that the Atlantic has. The big unknown at this point is the anthropogenic inventory of the Pacific. With nearly 50% of the total ocean volume the Pacific has the potential to be the largest oceanic reservoir for anthropogenic CO2. 4. COMPARISON WITH PRINCETON OCEAN BIOGEOCHEMISTRY MODEL Current IPCC anthropogenic estimates are primarily based on global carbon models. Ultimately, these models are necessary to predict the oceanic response to future climate scenarios. It is important, however, to validate these models. One way to compare results is to examine profiles of the average anthropogenic concentrations such as those shown in Figure 9. The model presented here is the Princeton Ocean Biogeochemistry Model (OBM). The Princeton OBM is based on the circulation of Toggweiler et al. [1989] with explicit parameterization for the biological and solubility carbon pumps [Sarmiento et al., 1995; Murnane et al., 1998]. On this scale the model-based concentrations for both the total anthropogenic CO2 and the increase since GEOSECS appear to be reasonably consistent with the data. The primary difference is slightly higher values at middepths in the data-based estimates. A more detailed examination, however, indicates that the regional distribution of the model-based estimates is significantly different than the data-based distribution. Figure 10 presents maps of the vertically integrated excess CO2 normalized to a unit area. The model shows a consistent decrease in column inventory toward the north. The lowest inventories in the data- based map are in a narrow band just south of the equator. The highest values are found in the southeastern Indian Ocean. Relatively high values are also observed in the Arabian Sea in the regions near the Red Sea and the Persian Gulf. The small patch of lower values immediately outside the Gulf of Aden does not result from low concentrations but rather results from the shallow water depth associated with the mid-ocean ridge in that area. The low values east of there, however, do result from lower concentrations near the southern tip of India. The total model-based inventory for the region north of 35°S is approximately 0.61 times the data-based inventory (Table 4). FIGURE 8: Sections of anthropogenic CO2 along (a) -57°E and (b) -92°E. Dots indicate sample locations used in sections. FIGURE 9: Profile of area weighted mean anthropogenic CO2 concentrations for model (solid symbols) and data-based (open symbols) estimates for main Indian Ocean basin (north of 35°S). Circles show increase since GEOSECS (1978-1995). Triangles show total increase since pre-industrial times. Figure II shows maps of total anthropogenic CO2 column inventory. As with the excess CO2, the model predicts decreasing anthropogenic concentrations north of 35°S. The data-based distribution pattern is similar to the data-based excess C02 pattern with a minimum inventory band south of the equator and higher values toward the north and south. Similar to the findings with excess CO2, the model-based anthropogenic inventory north of 35°S is approximately 0.68 times the data-based inventory (Table 4). The largest difference between the data-based results and the model is evident, however, in the Southern Ocean (south of 35°S). In this region the model anthropogenic inventory is nearly 2.6 times the data-based inventory (Table 4). The primary reason for this difference is the presence of a large convective cell in the model at approximately 55°S and 90°E in the Southern Ocean. This is a region of intense, unrealistic convection which pumps relatively high concentrations of anthropogenic CO2 down in excess of 4000 m. This problem is a known shortcoming with the mixing scheme used in several GCMs [e.g., England, 1995] but has never before been quantified in terms of its direct effect on anthropogenic CO2 storage by the models. It is beyond the scope of this paper to examine the details of the model physics; however, this same general trend of getting too much anthropogenic CO2 into the Southern Ocean has been observed in comparisons with three other global carbon models with a range of mixing and advective schemes [C. Sabine, unpublished results, 1998]. This cursory comparison with the Princeton OBM clearly demonstrates the diagnostic usefulness of comparing the data distributions with models. 5. CONCLUSIONS Although the general techniques proposed by Gruber et al. [1996] and Wallace [1995] can be important tools for estimating global anthropogenic CO2, careful consideration must be used when applying these techniques to new regions. Complicating factors such as those found in the Arabian Sea can influence the quality of the estimates if not properly addressed. An additional term had to be added to the basic ∆C* calculation to account for denitrification in the Arabian basin. For the excess CO2 calculations a categorical variable was used to remove regional biases in the GEOSECS fit. With the above mentioned modifications the anthropogenic inventory of the Indian Ocean was shown to be relatively small, approximately half of that found in the Atlantic. This study provides an important baseline for future studies of the Indian Ocean. The calculations presented here suggest that the oceanic increase in carbon storage (30%) has roughly kept pace with the atmosspheric increase (31%) over the past 18 years. Models predict that this trend is likely to change as atmospheric CO2 concentrations continue to rise in the future [Sarmiento et al., 1995]. As more CO2 enters the ocean, the carbonate ion concentration will become depleted. This will decrease the buffering capacity of the ocean and its ability to continue carbon uptake at the current rate. Comparison of future survey cruises in the Indian Ocean with the anthropogenic and total carbon values from this study will allow us to document future changes in ocean chemistry and better understand the oceanic response to global change. FIGURE 10: Maps of vertically integrated excess CO2 based on (a) data and (b) model estimates. Contours are in mol m^-2. Solid regions indicate land mask used for inventory estimates. Thin lines in Figure 10b indicate land regions used in Figure 10a. TABLE 4: Summary of Data Based and Model Based Inventory Estimates ______________________________________________________________ Total Southern Main Basin Main Basin Increase Anthro- Ocean Anthro- Excess since pogenic Anthro- pogenic CO2(χ) GEOSECS CO2(α) pogenic CO2(χ) PgC % PgC CO2(β) PgC PgC ------- -------- ---------- ---------- -------- Data 20.3±3 6.7±1 13.6±2 4.1±1 29.9 based Model 26.7 17.4 9.3 2.5 26.7 based ______________________________________________________________ (α) Area between 20°-120°E. (β) Latitude is < 35°S. (χ) Latitude is > 35°S. Finally, comparison of the spatial distribution of the anthropogenic carbon can be a powerful tool for understanding the carbon uptake of the models. The methods presented here provide a two point calibration for examining the response of the models to observed atmospheric CO2 increases. The anthropogenic CO2 data can also be subtracted from the TC02 measurements to provide an estimate of the pre-industrial TC02 distribution. Comparing these estimates with the steady state model distributions can provide insight into whether differences in the model and data-based anthropogenic inventories result from problems with the uptake parameterization or the basic physics and initialization parameters of the model. This paper is just the first step in the interpretation of the WOCE/JGOFS data set. Subsequent papers will analyze additional cruise data as they become available. Together. these analyses will significantly improve our understanding of the global carbon cycle. FIGURE 11: Maps of vertically integrated anthropogenic CO2 based on (a) data and (b) model estimates. Contours are in mol m-2. Solid regions indicate land mask used for inventory estimates. Thin lines in Figure 11b indicate land regions used in Figure 1la. ACKNOWLEDGMENTS. This work was accomplished with the cooperative efforts of the DOE CO2 Science Team. We thank B. Warren for organizing the WOCE Indian Ocean expedition, the captain and crew of the R/V Knorr, and the WOCE-HP personnel at sea. We. thank the chief scientists (M. McCartney, A. Gordon, L. Talley, W. Nowlin, J. Toole, D. Olson, J. Morrison, N. Bray, and G Johnson) and the CFC PIs (1. Bullister, R Fine, M. Warner, and R Weiss) for giving us access to their preliminary data for use in this publication. We also thank N. Metzl, G Eischeid, and C. Goyet for providing carbon data and T. Takahashi for providing S4I data and ∆pC02 maps. We thank R Murnane and T. Hughes for providing model results. Strong collaboration, cooperation, and input from N. Gruber and investigators in the NOAA Ocean Atmosphere Carbon Exchange Study (R Wanninkhof, R. Feely, J. Bullister, and T.-H. Peng) is also acknowledged along with the helpful comments of two anonymous reviewers. This work was primarily funded by DOE grant DE-FG02-93ER61540 with additional support by NSF/NOAA grant OCE-9120306. 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Johnson, Oceanographic and Atmospheric Sciences Division, Brookhaven National Laboratory, Upton, NY 11973. RM. Key, C.L. Sabine, and J.L. Sarmiento, Department of Geosciences, Princeton University, Princeton, NJ 08544. (key@geo.princeton.edu, sabine@geo.princeton.edu, andjls@splash.princeton.edu) F.J. Millero, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy., Miami, FL 33149. (fmillero@rsmas.miami.edu) A. Poisson, Laboratoire de Physique et Chimie Marines, Universite Pierre et Marie Curie, 4 Place Jussieu, Tour 24-25, 75720 Paris Cedex 05 France. (apoisson@ccr.jussieu.fr) D.W.R. Wallace, Abteilung Meereschemie, Institut fur Meereskunde an der Universität Kiel, Duesternbrooker Weg 20, D-24105 Kiel, Germany. (dwallace@ifm.uni-kieI.de) C.D. Winn, Marine Science Program, Hawaii Pacific University, 45045 Kamehameha Highway, Kaneohe, HI 96744-5297. (cwinn@soest.hawaii.edu) (Received May 11, 1998; revised November 24,1998; accepted November 24,1998.) APPENDIX E: REPRINT OF PERTINENT LITERATURE Key R. M., and P. D. Quay. 2002. U.S. WOCE Indian Ocean Survey: Final Report for Radiocarbon. Technical Report. Princeton University, Princeton, N.J. U.S. Woce Indian Ocean Survey: Final Report for Radiocarbon Robert M. Key and Paul D. Quay Ocean Tracer Laboratory; Technical Report 02-1 July 12, 2002 1.0 General Information The U.S. WOCE Indian Ocean Survey consisted of 9 cruises covering the period December 1, 1994 to January 22, 1996. All of the cruises used the R/V Knorr operated by the Woods Hole Oceanographic Institute. A total of 1244 hydrographic stations were occupied with radiocarbon sampling on 366 stations. The radiocarbon stations are shown as black dots in Figure 1. To give an indication of the total radiocarbon coverage for the Indian Ocean, the figure includes radiocarbon stations from WOCE sections S4I (Key, 1999; red dots) and I6S (Leboucher, et al., 1999; white dots) and from the earlier GEOSECS (Stuiver and Ostlund, 1983; brown dots) and INDIGO (Bard, et al., 1988; yellow dots) expeditions. Specific summary information on the 9 WOCE survey cruises is given in Table 1. TABLE 1: Summary for Survey Sections __________________________________________________________________ Chief ∆14C ∆14C Cruise Scientist Start End Stations Samples ------ ------------ ---------- ---------- -------- -------- I8SI9S M. McCartney 12/01/94 01/19/95 26 662 T. Whitworth Fremantle Fremantle Australia Australia I9N A. Gordon 01/24/95 03/05/95 22 364 D. Olson Fremantle Colombo Australia Sri Lanka I8NI5E L. Talley 03/10/95 04/15/95 20 414 M. Baringer Colombo Fremantle Sri Lanka Australia I3 W. Nowlin 04/20/95 06/07/95 20 462 B. Warren Fremantle Port Louis Australia Mauritius I5WI4 J. Toole 06/11/95 07/11/95 15 361 Port Louis Port Louis Mauritius Mauritius I7N D. Olson 07/15/95 08/24/95 22 373 S. Doney Port Louis Muscat D. Musgrave Mauritius Oman I1 J. Morrison 08/29/95 10/16/95 24 426 H. Bryden Muscat Singapore Oman China I10 N. Bray 11/11/95 11/28/95 6 127 J. Toole Dampier Singapore Australia China I2 G. Johnson 12/02/95 01/22/96 28 651 B. Warren Singapore Mombasa China Kenya __________________________________________________________________ 2.0 Personnel ∆14C sampling for cruise I8SI9S was carried out by Melinda Brockington (University of Washington). Personnel for the remainder of the cruises came from the Ocean Tracer Lab (OTL Princeton University) and included G. McDonald, A. Doerty, R. Key, T. Key, and R. Rotter. ∆14C (and accompanying δ13C) analyses were performed at the National Ocean Sciences AMS Facility (NOSAMS) at Woods Hole Oceanographic Institution. R. Key collected the data from NOSAMS, merged the files with hydrographic data, assigned quality control flags to the ∆14C and submitted the results to the WOCE office (4/02). R. Key is P.I. for the 14C data. P. Quay (U.W.) and A. McNichol (WHOI/NOSAMS) are P.I.s for the 13C data. In addition to collecting samples the shipboard 14C person was also responsible for operation of the underway pCO2 system provided by the OTL (Sabine and Key, 1997; Sabine, et al., 2000). 3.0 Results This ∆14C data set and any changes or additions supersedes any prior release. 3.1 Hydrography Hydrographic data from these cruises were submitted to the WOCE office by the chief scientists and are described in various reports which are available from the web site (http://whpo.ucsd.edu/data/tables/onetime/1tim_ind.htm). 3.2 ∆14C The ∆14C values described here were originally distributed in the NOSAMS data reports listed in Table 2 and given in full in the References. Those reports included results which had not been through the WOCE quality control procedures. For WOCE applications, this report supersedes the NOSAMS reports. TABLE 2: NOSAMS Data Report Summary _________________ Cruise Report ------- ------ I8SI9S 99-089 I7NI9N 99-144 I1 99-199 I8N 00-218 I3I5WI4 01-013 I2 02-001 _________________ All of the AMS samples from these cruise have been measured using the AMS methods outlined in Key et al., 1996 and citations therein (especially Mcnichol et al., 1994; Osborne et al. 1994; and Scheideret al. 1995). Table 3 summarizes the number of samples analyzed and the quality control flags assigned for each cruise. Approximately 98% of the samples collected were deemed to be "good" (flagged 2 or 6). Quality flag values were assigned to all ∆14C measurements using the code defined in Table 0.2 of WHP Office Report WHPO 91-1 Rev. 2 section 4.5.2. (Joyce, et al., 1994). No measured values have been removed from this data set. TABLE 3: Sample Analysis and QC Summary _______________________________________ Samples QC Flag Totals Cruise Analyzed 2 3 4 5 6 ------ -------- --- --- --- --- --- I8SI9S 662 636 6 8 0 12 I9N 368 354 4 3 4 3 I8NI5E 416 401 6 0 2 7 I3 463 448 5 0 1 9 I5WI4 366 342 3 1 5 15 I7N 383 370 3 0 10 0 I1 430 421 2 2 4 1 I10 127 127 0 0 0 0 I2 655 636 13 2 4 0 Total 3870 3735 42 16 30 47 _______________________________________ 4.0 Data Summary Figures 2-6 summarize the ∆14C data collected during the Indian Ocean survey. Only ∆14C measurements with a quality flag value of 2 ("good") or 6 ("replicate") are included in the figures. Figure 2 shows the ∆14C values with 2σ error bars plotted as a function of pressure. The mid depth ∆14C minimum which occurs around 2500 meters in the Pacific is not apparent in these data. In fact, there is very little variation in the deep and bottom water other than the previously reported decrease in ∆14C from south to north. All of the samples collected at a depth greater than 1000 meters have a mean ∆14C = -165.±25‰ (standard error = 0.5‰ with n=2086). A substantial fraction of this variability is due to the difference between the Southern Ocean and main basin deep waters. Figure 3 shows the deep (>1000m) ∆14C values plotted against silicate. The black and red points are from north and south of 35°S, respectively. The straight line shown in the figure is the least squares regression relationship derived by Broecker et al. (1995) based on the GEOSECS global data set. According to their analysis, this line (∆14C = -70 - Si) represents the relationship between naturally occurring radiocarbon and silicate for most of the ocean. They noted that the technique could not be simply applied at high latitudes as confirmed by this data set. Figure 4 shows all of the radiocarbon values plotted against potential alkalinity (defined as [alkalinity + nitrate]*35/salinity). The straight line is the regression fit (14C = -59 -0.962(PALK-2320) derived by Rubin and Key (2002) using GEOSECS measurements assumed to have no bomb-produced ∆14C. The value 2320 is the estimated surface ocean mean potential alkalinity. As with Figure 3 the black and red points in Figure 4 indicate measurements taken north and south of 35°S, respectively. Unlike the silicate plot (Figure 3), there is no apparent difference in the relationship for Southern Ocean vs Indian Ocean deep waters. The distance a point falls above the regression line is an estimate of the bomb radiocarbon contamination for the sample. Figures 5-9 show gridded sections of the ∆14C data. In each figure the water column is divided into upper (0-1000m) and lower (1000-bottom) portions. The data were gridded using the loess method (Chambers et al., 1983; Chambers and Hastie, 1991; Cleveland,1979; Cleveland and Devlin, 1988). The span for the fits was adjusted to be minimum and yet capture the large scale features. The contour interval is 10‰ for the upper water column and 20‰ for intermediate and deep water. Figure 5 and Figure 6 show the meridional ∆14C distribution in the eastern and western Indian Ocean. In both figures the distribution pattern is very similar to that seen in the Pacific Ocean WOCE samples. In the Pacific the maximum ∆14C values were frequently found in shallow water, but beneath the surface. In the Indian Ocean data a subsurface maximum is not so common. Both sections show intrusion of Circumpolar Deep Water from the south along the bottom and return flow of deep water at 2000-3000m. As with the Pacifiic the middepth waters have the lowest ∆14C values, however the middepth Indian Ocean waters have significantly higher values that corresponding Pacific waters. This pattern is consistent with a mean ageing of waters from the Atlantic to Indian to Pacific. Figure 7, Figure 8 and Figure 9 show zonal ∆14C sections along the WOCE lines I1 (~10°N), I2(~8°S) and I3(~20°S). Except for the western ends, the ∆14C contours in the upper kilometer are relatively flat. In each section the deep waters of the western basins have somewhat higher ∆14C than at the same depth in the eastern basins. The strength of this signal decreases from south to north and is almost certainly due to the western basins having a higher fraction of North Atlantic Deep Water. Figure 10 shows the meridional distribution of bomb produced ∆14C (via Rubin and Key, 2002) in the eastern and western Indian Ocean. The eastern section used all WOCE samples collected at depths less than 1000m and east of 85°E. The western section uses the same depth range, but samples from west of 75°E. Both sections are contoured and colored in potential density space rather against depth. One might expect a priori that the distributions would differ north of the equator due to the geography and difference in chemistry between the Bay of Bengal and Arabian Sea. Perhaps unexpected is the fact that the distributions differ significantly as far as 40°S. In the eastern section the maximum bomb ∆14C values are found between 40°S and 20°S and more or less uniformly from the surface down to the level where σθ~26.5. The western section has a maximum in the same latitude range but in this case the maximum occurs as a subsurface lens. Figure 1: AMS 14C station map for WOCE S4I. Figure 2: ∆14C results shown with 2σ error bars. Figure 3: ∆14C as a function of silicate for samples collected deeper than 1000m. The black points are from north of 35°S and the red points south of 35°. The straight line shows the relationship proposed by Broecker, et al., 1995 (∆14C = -70 - Si with radiocarbon in ‰ and silicate in µmol/kg). Figure 4: Based on the potential alkalinity method (Rubin and Key, 2002), the samples which plot above the line and have potential alkalinity values less than about 2400 µmole/kg are contaminated with bomb- produced 14C. Figure 5: ∆14C, along I8S and I9N in the eastern Indian Ocean. Figure 6: ∆14C along I7 in the western Indian Ocean. Figure 7: ∆14C along I1 in the northern Indian Ocean. Figure 8: ∆14C along I2 in the southern tropical Indian Ocean. Figure 9: ∆14C along I3 in the southern subtropical Indian Ocean at approximately 20°S. . Figure 10: Mean bomb-produced ∆14C sections in the eastern (A) and western (B) Indian Ocean, shown in potential density space for samples from the upper 1000m. Figure 11: (A) ∆14C and (B) bomb-produced ∆14C for the surface Indian Ocean from WOCE measurements. Figure 12: (A) ∆14C and (B) bomb-produced ∆14C on σθ=24.0. 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Chambers, J.M. and Hastie, T.J., 1991, Statistical Models in S, Wadsworth & Brooks, Cole Computer Science Series, Pacific Grove, CA, 608pp. Chambers, J.M., Cleveland, W.S., Kleiner, B., and Tukey, P.A., 1983, Graphical Methods for Data Analysis, Wadsworth, Belmont, CA. Cleveland, W.S., 1979, Robust locally weighted regression and smoothing scatterplots, J. Amer. Statistical Assoc., 74, 829-836. Cleveland, W.S. and S.J. Devlin, 1988, Locally-weighted regression: An approach to regression analysis by local fitting, J. Am. Statist. Assoc, 83:596-610. Elder, K.L., A.P. McNichol and A.R. Gagnon, Reproducibility of seawater, inorganic and organic carbon 14C results at NOSAMS, Radiocarbon, 40(1), 223-230, 1998 Joyce, T., and Corry, C., eds., Corry, C., Dessier, A., Dickson, A., Joyce, T., Kenny, M., Key, R., Legler, D., Millard, R., Onken, R., Saunders, P., Stalcup, M., contrib., Requirements for WOCE Hydrographic Programme Data Reporting, WHPO Pub. 90-1 Rev. 2, 145pp., 1994. Key, R.M., WOCE Pacific Ocean radiocarbon program, Radiocarbon, 38(3), 415-423, 1996. Key, R.M., P.D. Quay, G.A. Jones, A.P. McNichol, K.F. Von Reden and R.J. Schneider, WOCE AMS Radiocarbon I: Pacific Ocean results; P6, P16 & P17, Radiocarbon, 38(3), 425-518, 1996. Key, R.M. and P. Schlosser, S4P: Final report for AMS 14C samples, Ocean Tracer Lab Technical Report 99-1, January, 1999, 11pp. Leboucher, V., J. Orr, P. Jean-Babtiste, M. Arnold, P. Monfrey, N. Tisnerat- Laborde, A. Poisson and J.C. Duplessey, Oceanic radiocarbon between Antarctica and South Africa along WOCE section I6 at 30°E, Radiocarbon, 41, 51-73, 1999. McNichol, A.P., G.A. Jones, D.L. Hutton, A.R. Gagnon, and R.M. Key, Rapid analysis of seawater samples at the National Ocean Sciences Accelerator Mass Spectrometry Facility, Woods Hole, MA, Radiocarbon, 36 (2):237-246, 1994. NOSAMS, National Ocean Sciences AMS Facility Data Report #99-043, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, 2/16/1999. Osborne, E.A., A.P. McNichol, A.R. Gagnon, D.L. Hutton and G.A. Jones, Internal and external checks in the NOSAMS sample preparation laboratory for target quality and homogeneity, Nucl. Instr. and Methods in Phys. Res., B92, 158- 161, 1994. Rubin, S. and R.M. Key, Separating natural and bomb-produced radiocarbon in the ocean: The potential alkalinity method, Global Biogeochem. Cycles, in press, 2002. Sabine, C.L. and R.M. Key, Surface Water and Atmospheric Underway Carbon Data Obtained During the World Ocean Circulation Experiment Indian Ocean Survey Cruises (R/V Knorr, December 1994-January 1996), ORNL/CDIAC-103, NDP-064, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge TN, 89 pp., 1997. Sabine, C.L., R. Wanninkhof, R.M. Key, C. Goyet, R. Millero, Seasonal CO2 fluxes in the tropical Indian Ocean, Mar. Chem., 72, 33-53, 2000. Schneider, R.J., A.P. McNichol, M.J. Nadeau and K.F. von Reden, Measurements of the oxalic acid I/oxalic acid II ratio as a quility control parameter at NOSAMS, In Proceedings of the 15th International 14C Conference, Radiocarbon, 37(2), 693-696, 1995. Stuiver, M. and H.G. Ostlund, GEOSECS Indian Ocean and Mediterranean radiocarbon, Radiocarbon, 25(1), 1-29, 1983. _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ WHPO DATA PROCESSING NOTES I01E DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 1998-02-04 Anderson BTL/SUM Fixed line & expocode #s, & sta. dates i01esu.txt Changed first header from R/V KNORR, I1,KN145, 11 to R/V KNORR CR. KN145, LEG 12 WHP-ID I01E Added time stamp changed EXPOCODE from 316N145/11b to 316N145_12 changed WOCE SECT from I1 to I01E latitude was not left justified, corrected this deleted last record in file, it only had The following stations had the wrong date. The cast started before midnight and ended after midnight according to the time but the date used was the same for the BE, BO, and EN event codes. Sta. Event Original Changed to # Code Date Date ---- ----- -------- ---------- 966 EN 093095 100195 987 EN 100795 100895 996 EN 100995 101095 1002 EN 101095 101195 i1b.sea Changed first header EXPOCODE and WHP-ID to conform with .sum file. EXPOCODE 31ka45 to 316N145_12, and WHP-ID WOCE to I01E. Changed CRUISE DATES 082995-101695 to 093095-101695 Added time stamp Deleted last record in file, in only had CHANGED FILE NAME TO i01ehy.txt 1999-08-02 Schwartz CTD Submitted for DQE 1999-08-02 Schwartz Cruise Report Submitted 2002-01-08 Mantyla BTL DQE Submitted 2000-06-19 Kozyr CO2 Final Data Submitted I have put the final/public CO2-related data files for the Indian Ocean WOCE Section I1W and I1E to the WHPO ftp INCOMING area. There are two CO2 parameters in the files: Total CO2 and Total Alkalinity with quality flags. 2000-08-03 Bartolacci CTD ctd files for i01e and i01w split Since the splitting of I01 into east and west lines, the ctd files for this cruise have remained as one zip file containing all stations for both east and west lines. As per Lynne Talley, I have split the east stations from the total zip file (stations 962-1014 according to the sumfile) and rezipped them. They have replaced the original file which was renamed to indicate it contains all stations and moved to the original directory. 2000-09-14 Kappa Cruise Report cfc doc added to pdf file 2000-10-17 Jenkins He/Tr Submitted Reformatting needed 2000-11-15 Anderson HELIUM/NEON Converted to WOCE format I have put the Jenkins helium and neon in WOCE format. There were no quality codes so I set the HELIUM, DELHE3, and NEON to 2. 2001-01-04 Anderson CTDTMP/OXY/CTDOXY Update Needed Working on an updated copy of i01ehy.txt (ANDY_ROSS.i01ehy.nut) from Andy Ross at OSU. This is the same data as was previously on-line, but the nutrient data has been corrected for units (previously uM/L, now uM/kg). Before putting this file back on-line, need to fix a few other problems: a) CTDTMP units are in ITS-68, should be ITS-90. All data need to be multiplied by 0.99976 to convert to ITS-90. Need to update header. b) OXYGEN and CTDOXY are in wrong units. Need to be converted from ml/l to uM/kg. Need to update headers. THIS NEEDS TO BE DONE FIRST, before converting CTDTMP to ITS-90. c) Formatting is incorrect for PO4, CFC11+12, OXYGEN and CTDOXY. DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 2001-01-22 Anderson TCARBN/ALKALI Data reformatted Converted CTDTMP from -68 to -90, changed header. Reformatted data columns in hyd file to comply with WOCE specs. Removed FCO2 column and associated Quality code (was '1'). ALSO, changed the quality codes for previously merged ALKALI and TCARBN data from '1' to '2' where data is present. Realized after making other conversions, also needed to convert Theta from ITPS-68 to ITS-90. Used most up-to-date hyd file to make this conversion (multiplied all values by 0.99976). 2001-02-01 Anderson HE, DELHE3, NEON Data merged into BTL file Merged TRITUM, TRITIER, HELIUM, HELIER, DELHE3, DELHER, NEON, NEONER from Sarilee's reformateed data files into hyd file. Data merged ok. NOTE: There were two values submitted for 979/1/25 (sta/cst/samp) TRITUM and TRITIER. Only merged first value into hyd file. 2001-02-01 Anderson TRITUM/TRITIER Data merged into BTL file Merged TRITUM, TRITIER, HELIUM, HELIER, DELHE3, DELHER, NEON, NEONER from Sarilee's reformateed data files into hyd file. Data merged ok. NOTE: There were two values submitted for 979/1/25 (sta/cst/samp) TRITUM and TRITIER. Only merged first value into hyd file. 2001-06-21 Uribe BTL Exchange file online Bottle exchange files was put online. 2001-06-27 Uribe CTD Exchange file online CTD exchange files were put online. 2001-09-18 Wisegarver CFCs Submitted, update needed This is information regarding line: I01E ExpoCode: 316N145_12 Cruise Date: 1995/08/29 - 1995/09/28 From: WISEGARVER, DAVID Email address: wise@pmel.noaa.gov Institution: NOAA Country: USA The directory this information has been stored in is: 20010918.165552_WISEGARVER_I01E The format type is: ASCII The data type is: BottleFile The Bottle File has the following parameters: CFC-11,CFC-12 The Bottle File contains: CastNumber StationNumber BottleNumber SampleNumber WISEGARVER, DAVID would like the data PUBLIC. And would like the following done to the data: merge final dqe cfc's Any additional notes are: Submitted for D. Wyllie. CFC's on SIO98 Scale 2001-09-27 Mantyla NUTs/S/O DQE Report Submitted 2001-12-26 Uribe CTD Exchange file online CTD has been converted to exchange using the new code and put online. 2002-01-08 Hajrasuliha CTD Internal DQE completed created *check.txt file for the cruise created *.ps files for this cruise. 2002-01-08 Anderson BTL Exchange file online Made new exchange file and put online. 2002-01-08 Anderson BTL/SUM DQ report online, The .sea file with the results of Arnold Mantyla's data quality evaluation and QUALT2 flags has been put online. Corrected a couple of error in the .sum file and put new file online. Jerry Kappa has been sent the DQ report. 2002-02-28 Bartolacci CFCs DQE'd data submitted I have placed the updated dqe'd CFC data sent by Wisegarver in the following directory: .../onetime/indian/i01/i01e/original/ 2001.09.18_I01E_CFC_DQE_WISEGARVER included are data file and submission form README file. Data are in need of merging at this time. DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 2002-04-01 Anderson DELC13 Submitted Date: Mon, 1 Apr 2002 09:49:35 -0800 (PST) From: WHPO Website To: dgerlach@whoi.edu, jrweir@whpo.ucsd.edu, whpo@ucsd.edu Subject: WHPO DATA I01E: OTHER from GERLACH This is information regarding line: I01E ExpoCode: Cruise Date: 1995/09/30 - 1995/10/16 From: GERLACH, DANA Email address: dgerlach@whoi.edu Institution: WHOI Country: USA The file: C:\My Documents\C13- project\whpo_indian_march02\whpo_i01e.txt - 2667 bytes has been saved as: 20020401.094935_GERLACH_I01E_whpo_i01e.txt in the directory: 20020401.094935_GERLACH_I01E The data disposition is: • Public The file format is: • Plain Text (ASCII) The archive type is: • NONE - Individual File The data type(s) is: • Other: flagged 13C data The file contains these water sample identifiers: • Cast Number (CASTNO) • Station Number (STATNO) • Bottle Number (BTLNBR) GERLACH, DANA would like the following action(s) taken on the data: • Merge Data • Place Data Online Any additional notes are: • NOSAMS expocode affiliated with this line is: 316N145/11. Any questions or concerns, please contact • Dana Gerlach (dgerlach@whoi.edu) or • Ann McNichol (amcnichol@whoi.edu). 2002-04-12 Buck C14 Submitted Moved data from /usr/export/ftp-incoming to i01/i01e/original/20020410_KEY_I1_C14. It is a CSV file and I added the following heading to it: #I01E/W,316N145_11-12,Key Data belongs to both I01E and I01W. 2002-08-13 Anderson C13/C14/CO2/ALK/CFCs Data Online Merged the DELC14 and C14ERR from Key, the DELC13 from Gerlach, the TCARBN and ALKAL from Kozyr, and the CFCs from Wisegarver. Made new exchange file. Merge notes for i01e: Merged the DELC14 and C14ERR from file I1.C14 found in /usr/export/ html- public/data/onetime/indian/i01/i01e/original/20020410_KEY_I1_C14 into the online file 20010927WHPOSIOSA. Merged the DELC13 from file 20020401.094935_GERLACH_I01E_whpo_i01e.txt found in /usr/export/html-public/data/onetime/indian/i01/ i01e/original/20020401.094935_GERLACH_I01E into the online file. Merged the new TCARBN and ALKAKI from file i1ecarb.dat found in /usr/export/ html-public/data/onetime/indian/i01/ i01e/original/2000.06.19_I1_CARB_KOZYR into online file. Merged the new CFC's from file: 20010918.165552_WISEGARVER_I01E_i01e_CFC_DQE.dat found in /usr/export/html-public/data/onetime/indian/i01/ i01e/original/2001.09.18_ I01E_CFC_DQE_WISEGARVER into the online file. 2002-08-15 Anderson He/Tr/Helium/Neon Data Online Merged the DELHE3, DELHER, HELIUM, HELIER, NEON, NEONER, TRITIUM, and TRITER from Jenkins. Made new exchange file. Merge notes for i01e: HE3, DELHER, HELIUM, HELIER, NEON, NEONER from file wihe.dat found in /usr/export/html-public/data/onetime/indian/i01/ i01e/original/2000.10.17_I01E_TRITIUM_HELIUM_JENKINS into online file 20020813WHOPSIOSA. Merged the TRITIUM and TRITER from file witrit.dat found in above directory into online file. This merging had been done earlier by Stacey Anfuso but there is no rcs (at least I can't find it) and the file she merged appears not to have been put online or somehow was replaced with a file that did not have these parameters. DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 2002-10-05 Diggs BTL Units corrected Fixed original WOCE formatted bottle file per Tim Boyer's (NODC/OCL) suggestions to me. Units line: This is the units line from i01e_hy1.csv: DBAR,ITS-90,PSS-78,,PSS-78,,UMOL/KG,,UMOL/KG,,UMOL/KG,,UMOL/KG,, UMOL/KG,,UMOL/KG,,PM/K,,GPM/K,,G T,,U UMOL/K,,PERCNT,,G /MILL,, /MILLE,,NMOL/KG,,E UMOL/K,,GUMOL/K,,,/MILLE,NMOL/KG, PERCNT,NMOL/KG,ITS-90,TU" Fixed units line, re-made HYD Exchange, NetCDF and inventories. Re-zipped all relevant files, checked in JOA3.1 (OSX), copied files to DVD 3.0 online site as well. Tarballed inventory, exchange, and NetCDF and sent to Shannon Niou of NODC for inclusion on the WOCE Version 3 DVD. 2003-04-16 Muus CTDs/OXY/DELC13 Data Online Merged DELC13 decimal-2-data into bottle file. Merged new CTDPRS, CTDTMP, CTDSAL, CTDOXY, THETA, SALNTY & OXYGEN from WHOI into bottle file. Notes on I01E merging Apr 16, 2003 D. Muus 1. Changed all Helium and Tritium quality flag 1s associated with missing data to 9s. 2. Merged DELC13 from: /usr/export/html-public/data/onetime/indian/i01/i01e/original/ 20020401.094935_GERLACH_I01E/20020401.094935_GERLACH_I01E_whpo_ i01e.txt into current web bottle file (20021005WHPOSIOSCD) to replace 1 decimal place data with 2 decimal place DELC13 data. 3. Merged CTDPRS, CTDTMP, CTDSAL, CTDOXY, THETA, SALNTY, & OXYGEN from: Jane Dunworth, WHOI, email of March 24, 2004. email data can be found in: /usr/export/html-public/data/onetime/indian/i01/i01e/original/ 2003.04.16.I01E_C13_CTDPTSO_SAL_OXY_MERGE_MUUS/ dunworth.email030324.i01e.btldata Prior to merging, ITS-68 CTDTMP and THETA were changed to ITS-90 using ITS-90 = 0.99976(ITS-68) and CTDOXY and OXYGEN changed from ml/l to UMOL/KG using cvuwoce on minerva.ucsd.edu. 4. 2001/01/23 ANFUSO, S. note in Data History. NUTRIENTS: Data was originally submitted in uM/L units, PI recalculated and resubmitted in uM/kg units. Also, original submission of nitrate data was actually nitrate nitrite. This error has been corrected in current data submission. Nutrients unchanged this version since only small changes in CTD pressure, salinity and temperature for samples with nutrient values. 5. Made new exchange file for Bottle data. 6. Checked new bottle file with Java Ocean Atlas. 2005-02-28 Anderson HELIUM/NEON Data Online i01e and i01w Found file i1he.txt in .../indian/i01/i01/original/2000.10.04_I1_BOTTLE. This file contains the deep DELHE3, HELIUM, NEON, DELHER, HELIER, and NEONER for i01e and i01w. I merged these parameters into the online files, and made new exchangeand netcdf files. There were no Q1 or Q2 flags so I set them to 2. 2008-06-17 Kappa Cruise Report Added C14 & CO2 reports & Data Processing Notes Added these WOCE/CCHDO Data Processing Notes Added 4 reports to pdf and text versions of cruise report: 1) Carbon Dioxide, Hydrographic and Chemical Data 2) Coulometric Total Carbon Dioxide Analysis 3) Assessment of the Quality of the Shipboard Measurements of Total Alkalinity 4) Anthropogenic CO2 Inventory 5) U.S. Woce Indian Ocean Survey: Final Report for Radiocarbon WHPO DATA PROCESSING NOTES I01W DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 1998-02-04 Anderson BTL/SUM Fixed line & expocode #s, & sta.dates i01wsu.txt - Changed first header from R/V KNORR, I1,KN145, 11 to: R/V KNORR CR. KN145, LEG 11 WHP-ID I01W Added time stamp changed EXPOCODE from 316N145/11a to 316N145_11 changed WOCE SECT from I1 to I01W latitude was not left justified, corrected this The following records had the wrong date. The cast started before midnight and ended after midnight according to the time but the date used was the same for the BE, BO, and EN event codes. Sta. Event Original Changed to Code Date Date --- ----- -------- ---------- 857 BO 082995 083095 862 EN 083195 090195 880 EN 090695 090795 885 BO 090795 090895 885 EN 090795 090895 891 EN 090895 090995 897 EN 091095 091195 904 EN 091295 091395 911 BO 091495 091595 911 EN 091495 091595 915 BO 091595 091695 915 EN 091595 091695 927 EN 091895 091995 934 BO 092095 092195 934 EN 092095 092195 937 EN 092195 092295 944 EN 092395 092495 954 BO 092595 092695 954 EN 092595 902695 i1a.sea Changed first header EXPOCODE and WHP-ID to conform with .sum file. EXPOCODE 31ka45 to 316N145_11, and WHP-ID WOCE to I01W. Changed CRUISE DATES 082995-101695 to 082995-092895 Added time stamp Deleted last record in file, it only had CHANGED FILE NAME TO i01why.txt 1998-09-16 Morrison CTD Submitted Plots, unencrypt data for workshop, NO public distrib after workshop 1998-09-29 Morrison CTDOXY not yet submitted, 50 stas have bad ctd 02. Bob Millard will take another look at them 1998-09-29 Talley BTL Data Update: Following changes ftp'd to WHPO. Replace older HYD file with this one (OK'd by PI): 1. Combine i01e and i01w into one line: i01 2. Change expocode from 31ka45 to 316N145 3. Bottle flag for station 1005, 1, 23 at 349.7 dbar is 3 and salinity is 4. It looks like all nutrients are bad here as well. I suggest that they all be flagged 4. Oxygen doesn't look out of place, but maybe for consistency, it should be flagged 3. 1998-12-22 Srinivasan He/Tr Deep Submitted Preliminary, not for DQE This is Ashwanth Srinivasan from Noble Gas Isotope Lab , RSMAS, Univ of Miami. We have submitted four files, i7he.txt, i9he.txt and i1he.txt and readme.he to the incoming directory at your ftp site. These files contain tritium, helium and neon data from WOCE I7N, I9N and I1 cruises. These data are preliminary and proprietary and the format is explained in the readme.he file. In case of problems or questions please email to one of the following addresses: Zafer Top: ztop@rsmas.miami.edu Ashwanth Srinivasan: asrinivasan@rsmas.miami.edu DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 1999-04-06 Bartolacci SUM Website Updated S.Anderson's (1998-02-04) updated files online 1999-05-25 Top He/Tr Deep Data are Public My helium-tritium data from IO legs I1-I7N and I9N may now be made public. It should be kept in mind though that we are working on the synthesis ; some modifications may occur. Also there are some papers are in progress; interested parties should check with the tracer group (Schlosser, Jenkins, Lupton, Top) 1999-06-30 Morrison CTD/BTL/SUM Submitted 6/27/99 The WHOI processing programs could not handle 4 digit station numbers, therefore the processed data as passed to me for final approval had files with station numbers 857 - 999 and 00 - 14. I changed the names of the CTD files and the stations numbers in the CTD, SEA and SUM files to reflect the actual WOCE stations numbers: 857 - 1014. John M. Morrison, Chief Scientist, WOCE I1 6/29/99 I have just placed the final, corrected data for WOCE Indian Ocean Leg I1 on your server. All of the calibration documention is in the directory DOC. Sorry that this was not submitted sooner, but I did not receive the data until last fall and was busy cleaning up JGOFS Indian Ocean and Southern Ocean data for submission to the JGOFS database. As you can see, the WOCE I1 dataset has some problems with the CTD data in that it was necessary to use Falmouth Scientific CTD's for the cruise (all of the WOCE Neil Brown WHOI CTD's were not working when the ship left of the WOCE Neil Brown WHOI CTD's were not working when the ship left Muscat, Oman. Let me know if you have received this dataset. 1999-06-30 Morrison CTD Data are Final I have just placed the final, corrected data for WOCE Indian Ocean Leg I1 on your server. All of the calibration documention is in the directory DOC. As you can see, the WOCE I1 dataset has some problems with the CTD data in that it was necessary to use Falmouth Scientific CTD's for the cruise (all of the WOCE Neil Brown WHOI CTD's were not working when the ship left Muscat, Oman. 1999-07-26 Swartz CTD/DOC Data Update: 1999-09-29 Falkner BA Data Update: The quality of the Ba data from most WOCE legs in the Indian Ocean turned out to be quite poor; far worse than attainable analytical precision (+/-20% as opposed to 2%). We recorded many vials which came back with loose caps and evaporation associated with that seems to be the primary problem. The only hope I have of producing a decent data set is to run both Ba and a conservative element simultaneously and then relating that to the original salinity of the sample. We will be taking delivery on a high resolution ICPMS here at OSU sometime this winter which would make the project analytically feasible and economical. I do not presently have the funds in hand to do this and so have archived the samples for the time being. I don't think the WHPO would derive any benefit from the present data set. KKF 1999-12-22 Elder Cruise Report Radiocarbon Data Report Submitted 2002-01-08 Mantyla BTL DQE Submitted emailed by S. Anderson DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 2000-03-27 Morrison CTD/BTL Website Updated: Data are Public not hearing any decenting comments from my fellow PI's, I release the WOCE I1 data set to the general public. 2000-05-01 Warner CFCs Data ata are public I just uploaded the revised CFC data for WOCE I1. It should be made public once it is merged. I have also included a report to be merged (eventually) into the metadata files. 2000-06-19 Diggs ALKALI/TCARBN Submitted Bottle: (tcarbn, alkali) data file received in INCOMING. In perfect WHP format. Will be merged asap. From Alex Kozyr I have put the final/public CO2-related data files for the Indian Ocean WOCE Section I1W and I1E to the WHPO ftp INCOMING area. There are two CO2 parameters in the files: Total CO2 and Total Alkalinity with quality flags. Please confirm the data submission. 2000-08-02 Kappa Cruise Report pdf, txt docs online; need cfc report 2000-08-03 Bartolacci CTD ctd files for i01e and i01w split Since the splitting of I01 into east and west lines, the ctd files for this cruise have remained as one zip file containing all stations for both east and west lines. As per Lynne Talley, I have split the east stations from the total zip file (stations 962-1014 according to the sumfile) and rezipped them. They have replaced the original file which was renamed to indicate it contains all stations and moved to the original directory. 2000-08-12 Ross SAL/NUTs/NITRAT Data Update: Per your request - I've attached i0why.nut and i01ehy.nut files containing nutrient data in the units of umol/kg. The original I01WHY.txt and I01EHY.txt files that contained nutrient data in umol/liter units were downloaded from the WOCE program office sites: http://whpo.ucsd.edu/data/onetime/indian/i01/i01e/index.htm and http://whpo.ucsd.edu/data/onetime/indian/i01/i01w/index.htm and were used as the data sources. The attached files are in text format. For your records, in the conversion process the bottle salinity values were used to determine sample density along with the mean laboratory temperature for each leg as determined from our nutrient analysis notes. When a bottle salinity value was unavailable, the corresponding CTD salinity value was used. The mean lab temperature for I01W was 25∞C and 26∞C for I01E. An important note: We also realized that the nitrate in the original files was in fact nitrate+nitrite. This has also been corrected in the new file versions that are attached. 2000-09-07 Huynh Cruise Report Website Update cfc report added to txt version; pdf pending 2000-09-14 Kappa Cruise Report cfc doc added to pdf file 2000-10-04 Uribe BTL Found data newer than file online Moved file i01hy.txt from incoming file in /usr/export/. Website indicated i01e was equivalent to i01w. File stamp is WHPOSIO19980928LDT. Online stamp is WHPOSI019980204SA. This indicates file data to be more recent than online version. Path is i01/i01e/original/1998.09.28_HY_LDT. 2000-10-17 Jenkins TRITUM Preliminary Data Submitted * Files for Tritium Data: WOCE Indian Ocean = WITrit.dat Contains all legs WOCE Pacific P10 = WP10Trit.dat WOCE Pacific P13 = WP13Trit.dat WOCE Pacific P14c = WP14cTrit.dat WOCE Pacific P18 = WP18Trit.dat WOCE Pacific P19 = WP19Trit.dat WOCE Pacific P21 = WP21Trit.dat SAVE South Atlnt = SAVETrit.dat * Column Layout as follows: Station, Cast, Bottle, Pressure, Tritium, ErrTritium * Units as follows: Tritium and ErrTritium in T.U. * All data are unfortunately still preliminary until we have completed the laboratory intercomparision and intercalibration that is still underway. DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 2000-10-17 Jenkins HELIUM/DELHE3 Preliminary He, DelHe3, Neon Submitted *Files for Helium and Neon Data: WOCE Indian Ocean = WIHe.dat Contains all legs WOCE Pacific P10 = WP10He.dat WOCE Pacific P18 = WP18He.dat WOCE Pacific P19 = WP19He.dat WOCE Pacific P21 = WP21He.dat * Column Layout as follows: Station, Cast, Bottle, Pressure, Delta3He, ErrDelta3He, ConcHelium, ErrConcHelium, ConcNeon, ErrConcNeon * Units as follows: Delta3He and ErrDelta3He in % ConcHelium, ErrConcHelium, ConcNeon, and ErrConcNeon in nmol/kg * Null values (for ConcNeon and ErrConcNeon only ) = -9.000 * All data are unfortunately still preliminary until we have completed the laboratory intercomparision and intercalibration that is still underway. * Files for Helium and Neon Data: WOCE Indian Ocean = WIHe.dat Contains all legs WOCE Pacific P10 = WP10He.dat WOCE Pacific P18 = WP18He.dat WOCE Pacific P19 = WP19He.dat WOCE Pacific P21 = WP21He.dat * Column Layout as follows: Station, Cast, Bottle, Pressure, Delta3He, ErrDelta3He, ConcHelium, ErrConcHelium, ConcNeon, ErrConcNeon * Units as follows: Delta3He and ErrDelta3He in % ConcHelium, ErrConcHelium, ConcNeon, and ErrConcNeon in nmol/kg * Null values (for ConcNeon and ErrConcNeon only ) = -9.000 * All data are unfortunately still preliminary until we have completed the laboratory intercomparision and intercalibration that is still underway. 2000-11-08 Anderson HELIUM/NEON Reformatted by WHPO I have put the Jenkins helium and neon in WOCE format. There were no quality codes so I set the HELIUM, DELHE3, and NEON to 2. 2000-11-13 Anderson TRITUM Reformatted by WHPO I have put the Jenkins tritium data into WOCE format. There were no quality codes so I set the TRITUM to 2. 2000-11-21 Anfuso NUTs Update Requested Dear Dr. Gordon, We are reviewing all data submitted to WHPO for the Indian Ocean WOCE cruise lines and would like to request that you resubmit the nutrient data for I01E/I01W in uM/Kg units. The current data submission indicates the nutrient values are in uM/L units. All other nutrient data submissions from you research group for the Indian Ocean WOCE lines indicate the data have been submitted in uM/Kg units. 2000-11-27 Uribe He/Tr Shallow Data Update: Files tritfrmt.txt, savetrit.dat, witrit.dat, heformat.txt and wihe.dat were moved from Jenkins' original data directory. witrit.dat contians tritium data for the indian cruises. wihe.dat contains helium data for indian cruises. These files contain original data that was later re-formatted by S. Anderson. Files received by Jenkins on October 17th, 2000. 2001-01-23 Anfuso BTL BTL file reformatted Bottle: (ctdtmp, ctdoxy, theta, oxygen, silcat, nitrat, nitrit, phspht, tcarbn, alkali) NUTRIENTS: Data was originally submitted in uM/L units, PI recalculated and resubmitted in uM/kg units. Also, original submission of nitrate data was actually nitrate nitrite. This error has been corrected in current data submission. CTDOXY & OXYGEN: Data was originally in ml/l, Sarilee converted to uM/kg. FCO2: Removed this data column and associated quality flag. All data values were -9.0. CTDTMP & Theta: Converted data from ITPS-68 to ITS-90. TCARBN & ALKALI: Changed quality flag from 1 to 2 where data exists. DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 2001-02-01 Anfuso He/Tr/Shallow Website Updated: Data Online Bottle: (tritum, helium, delhe3, neon, triter, helier, delher, neoner) Merged TRITUM, TRITER, HELIUM, HELIER, DELHE3, DELHER, NEON, NEONER data into hyd file. Updated hyd file is on-line. NOTE: The following NEON data (sta/cst/samp) had a -9.000 data value, with a -0.045NMOL/KG NEONER value. This doesn't make sense. Assumed samples were never drawn, NEONER value changed to -9.000. 866/1/28, 26, 24, 22, 21; 873/1/9; 874/1/2 Also, the following TRITUM and TRITIER had duplicate data values submitted, only merged first value into hyd file: 880/1/9;885/1/1;945/1/1;951/1/21 2001-02-05 Anfuso HE/TR/NEON Data merged into BTL file Merged TRITUM, TRITIER, HELIUM, HELIER, DELHE3, DELHER, NEON, NEONER from Sarilee's reformateed data files into hyd file. Data merged ok. NOTE: The following NEON data (sta/cst/samp) had a -9.000 data value, with a -0.045NMOL/KG NEONER value. This doesn't make sense. Assumed samples were never drawn, NEONER value changed to -9.000. 866/1/28, 26, 24, 22, 21; 873/1/9; 874/1/2 Also, the following TRITUM and TRITIER had duplicate data values submitted, only merged first value into hyd file: 880/1/9;885/1/1;945/1/1;951/1/21 2001-02-06 Anfuso ALKALI/TCARBN Website Updated: Data Online Merged updated TCARBN and ALKALI data and quality codes into hyd file. Merged over preliminary version of data. Updated hyd file is on-line. Merging notes are in original subdir 2000.06.19_I01W_CARB_KOZYR/00_Readme. 2001-02-07 Mantyla NUTs/S/O DQE Begun Sure, I would be glad to look over the Indian Ocean data for you. Sarilee has started plotting up I01 for me to start on. 2001-06-21 Uribe BTL Exchange file online Bottle exchange file was put online. 2001-06-22 Muus He/Tr Deep Submitted/not on web I01E,I01W Z. Top deep helium/tritium received May 25, 1999 not on web. 2001-08-23 Mantyla OXYGEN Decimal correction needed I took another look at the exchange format for I 01E. The nutrient conversion back to UM/L appear to be OK, I had misread one station. However, the O2 data, listed as ML/L, should carry two more decimal places. The conversion is going from a 4 significant firure to only 2. What is supposed to be listed under the depth column? Since it appears with each sample and is next to the CTD pressure, I would assume that the sample depth would be listed there. However, what is showing up is the bottom sounding for every sample. At 08:55 AM 8/23/01 -0700, James H. Swift wrote: WHPO - Would someone kindly create a new bottle exchange file for I01E (316N145_12). There is a clear problem with the oxygens and nutrients in the present exchange file on line for this cruise (i01e_hy1.csv) and I want to see if it goes away when we create a new file. 2001-08-29 Top NEON Status Changed to Public Zafer - Is it safe to assume that all WOCE One-Time Survey neon data from you are now public? Jim Yes they are. - Zafer 2001-11-01 Mantyla NUTs/S/O DQE Report Submitted 2001-12-17 Hajrasuliha CTD/BTL Internal DQE completed The following are results from the examminer.pl and plotter.pl code that were run on this cruise. Not all of the errors are reported but rather a summery of what was found. For more information you can go to the cruise directory, and look at the NEW file called CruiseLine_check.txt. Two plot files are also present. _oxy.ps and _sal.ps _oxy.ps and _sal.ps files created. Exchange CTD file not created for this cruise. DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 2001-12-26 Uribe CTD Exchange file online CTD has been converted to exchange using the new code and put online. 2002-01-08 Anderson BTL Exchange file online Made new exchange file and put online. 2002-01-08 Anderson BTL/SUM DQ report online, The .sea file with the results of Arnold Mantyla's data quality evaluation and QUALT2 flags has been put online. Corrected a couple of error in the .sum file and put new file online. Jerry Kappa has been sent the DQ report. 2002-02-28 Bartolacci CFC's DQE'd data submitted, ready to be merged I have placed the updated dqed CFC data sent by Wisegarver in the following directory .../onetime/indian/i01/i01w/original/ 2001.09.18_I01W_CFC_DQE_WISEGARVER included are data file and submission form README file. Data are in need of merging at this time. 2002-04-01 Gerlach DELC13 Submitted Date: Mon, 1 Apr 2002 09:51:17 -0800 (PST) From: WHPO Website To: dgerlach@whoi.edu, jrweir@whpo.ucsd.edu, whpo@ucsd.edu Subject: WHPO DATA I01W: OTHER from GERLACH This is information regarding line: I01W ExpoCode: 316N145/11 Cruise Date: 1995/08/29 - 1995/10/16 From: GERLACH, DANA Email address: dgerlach@whoi.edu Institution: WHOI Country: USA The file: C:\My Documents\C13- project\whpo_indian_march02\whpo_i01w.txt - 8503 bytes has been saved as: 20020401.095117_GERLACH_I01W_whpo_i01w.txt in the directory: 20020401.095117_GERLACH_I01W The data disposition is: Public The file format is: Plain Text (ASCII) The archive type is: NONE - Individual File The data type(s) is: Other: flagged 13C data The file contains these water sample identifiers: Cast Number (CASTNO) Station Number (STATNO) Bottle Number (BTLNBR) GERLACH, DANA would like the following action(s) taken on the data: Merge Data Place Data Online Any additional notes are: Questions or concerns, please contact: Dana Gerlach (dgerlach@whoi.edu) or Ann McNichol (amcnichol@whoi.edu) Date: Mon, 1 Apr 2002 10:36:36 -0800 (PST) From: WHPO Website To: dgerlach@whoi.edu, jrweir@whpo.ucsd.edu, whpo@ucsd.edu Subject: WHPO DATA I01W: DOC/OTHER from GERLACH This is information regarding line: I01W ExpoCode: 316N145/11 Cruise Date: 1995/08/29 - 1995/10/16 From: GERLACH, DANA Email address: dgerlach@whoi.edu Institution: WHOI Country: USA The file: C:\My Documents\C13- project\whpo_indian_march02\i01w_desc.txt - 259 bytes has been saved as: 20020401.103636_GERLACH_I01W_i01w_desc.txt in the directory: 20020401.103636_GERLACH_I01W The data disposition is: Public The file format is: Plain Text (ASCII) The archive type is: NONE - Individual File The data type(s) is: Documentation\n Other: flagged 13C replicate data The file contains these water sample identifiers: Cast Number (CASTNO) Station Number (STATNO) Bottle Number (BTLNBR) GERLACH, DANA would like the following action(s) taken on the data: Other: use as reference Any additional notes are: This description file lists the individual flags for the replicate values. \n It is a detailed listing of those stations which have c13f = 6. DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 2002-04-10 Key C14 Submitted The file: I1.C14 - 87908 bytes has been saved as: 20020410.072032_KEY_ALL†INDIAN†OCEAN_I1.C14 in the directory: 20020410.072032_KEY_ALL†INDIAN†OCEAN The data disposition is: Public The bottle file has the following parameters: STATION, CAST, BOTTLE, DELC14, C14ERR, C14F The file format is: Plain Text (ASCII) The archive type is: NONE - Individual File The data type(s) is: Bottle Data (hyd) The file contains these water sample identifiers: Cast Number (CASTNO), Station Number (STATNO), Bottle Number (BTLNBR) KEY, ROBERT would like the following action(s) taken on the data: Merge Data, Place Data Online, Update Parameters Any additional notes are: I've included the C14 from the French occupation of I6S. All files are same format. Tool does not accept mput syntax 2002-08-14 Anderson BTL C13/C14/Data Online Merged DELC14 and C14ERR from Key, DELC13 from Gerlach, TCARBN adn ALKALI from Kozyr, and CFCs from Wisegarver. Made new exchange file. Merge notes for i01w: Merged the DELC14 and C14ERR from file I1.C14 found in /usr/export/ html- public/data/onetime/indian/i01/i01w/original/20020410_KEY_I1_C14 into the online file 20011026WHPOSIOSA. Merged the DELC13 from file 20020401.095117_GERLACH_I01W_whpo_i01w.txt found in /usr/export/html- public/data/onetime/indian/i01/i01w/original/20020401.095117_ GERLACH_I01W into the online file. Merged the new TCARBN and ALKAKI from file i1wcarb.dat found in /usr/export/ html- public/data/onetime/indian/i01/i01w/original/2000.06.19_I01W_CARB_ KOZYR into online file. Merged the new CFC's from file 20010918.165933_WISEGARVER_I01W_i01w_CFC_DQE.dat found in /usr/export/html- public/data/onetime/indian/i01/i01w/original/2001.09.18_ I01W_CFC_DQE_WISEGARVER into the online file. 2002-08-15 Anderson He/Tr/Neon Website Updated: Data Online Merged the DELHE3, DELHER, HELIUM, HELIER, NEON, NEONER, TRITIUM, and TRITER from Jenkins. Made new exchange file. Merge notes for i01w: Merged the DELHE3, DELHER, HELIUM, HELIER, NEON, NEONER from file wihe.dat found in /usr/export/html- public/data/onetime/indian/i01/i01w/original/2000.10.17_I01w_TRITI UM_HELIUM_ JENKINS into online file 20020814WHOPSIOSA. Merged the TRITIUM and TRITER from file witrit.dat found in above directory into online file. This merging had been done earlier by Stacey Anfuso (2001/02/01) according to the rcs, but the file she merged appears not to have been put online or somehow was replaced with a file that did not have these parameters. DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 2003-04-11 Muus CTD/C13 Data merged into BTL file Merged DELC13 decimal-2-data into bottle file. Merged new CTDPRS, CTDTMP, CTDSAL, CTDOXY, THETA, SALNTY & OXYGEN from WHOI into bottle file. Changed some quality flags per WHOI notes and results of Java Ocean Atlas check. Notes file sent to Jerry with details. Notes on I01W merging Apr 11, 2003 D. Muus 1. Merged DELC13 from: /usr/export/html-public/data/onetime/indian/i01/i01w/original/ 20020401.095117_GERLACH_I01W/20020401.095117_GERLACH_I01W_ whpo_i01w.txt into current web bottle file (20020815WHPOSIOSA) to replace 1 decimal place data with 2 decimal place DELC13 data. 2. Changed all Helium and Tritium quality flag 1s associated with missing data to 1s. 3. Replaced all BTNNBR, CTDSAL & CTDOXY quality flags with new flags received March 24, 2003, from Jane Dunworth, WHOI 4. Changed flag 1s for Station 863 to 4s per WHOI message: From jdunworth@whoi.edu Tue Mar 25 06:21:13 2003 found this is in the cruise summary info. it seems like this cruise had serious problems with calibration and instrumentation issues. you might want to change the ctdsal & ctdoxy flags to 3 (questionable) or 4 (bad) for sta 863. STATION 863 Made the internally recording (IR) backup CTD, CTD 1338, the primary data for the station instead of CTD 9. CTD9's oxygen and salinity in the down profile were bad due to noisy pressure requiring heavy interpolation. ICTD 1338 data was used to make the down 2-db file. CTD 9's info was left with the bottle file. There were problems makeing the bottle file from the IR CTD. Note, there are different up and down cals!, one for CTD1338, the other for CTD9. Following note also found in Documentation: Station 863: CTD9 with ICTD1338 in Memory mode. After Test station for CTD9, CTD 9 opened and found dessicant packs to be caught btw boards, causing components on board to short out. Thought was fixed, but everything dropped out twice during this station. -USE ICTD1338 DATA FOR THIS STATION 5. Merged CTDPRS, CTDTMP, CTDSAL, CTDOXY, THETA, SALNTY, & OXYGEN from: Jane Dunworth, WHOI, email of March 24, 2004. email data can be found in: /usr/export/html- public/data/onetime/indian/i01/i01w/original/ 2003.04.08.I01W_C13_CTDPTS_SAL_OXY_MERGE_MUUS/ dunworth.email030324.i01w.btldata Prior to merging, ITS-68 CTDTMP and THETA were changed to ITS-90 using ITS-90 = 0.99976(ITS-68) and CTDOXY and OXYGEN changed from ml/l to UMOL/KG using cvuwoce on minerva.ucsd.edu. 6. Station 863 Sample 36 was deleted because CTDTMP & CTDSAL = 0 at 16 N Latitude surface. STNNBR 863 CTDPRS 2.4 SALNTY 35.6305 NITRIT 0.63 Remaining parameters -9 CASTNO 1 CTDTMP 0.0029 OXYGEN 201.3 PHSPHT 1.24 SAMPNO 36 CTDSAL 0.0000 SILCAT 7.81 CFC-11 1.864 BTLNBR SIH024 CTDOXY 358.4 NITRAT 14.10 CFC-12 1.055 7. 2001/01/23 ANFUSO, S. note in Data History. NUTRIENTS: Data was originally submitted in uM/L units, PI recalculated and resubmitted in uM/kg units. Also, original submission of nitrate data was actually nitrate nitrite. This error has been corrected in current data submission. Nutrients unchanged this version since only small changes in CTD pressure, salinity and temperature for samples with nutrient values. 8. Following CTDSAL and CTDOXY values differ from bottle values. QUALT1 was 2. Sta/Ca/Smp CTDPRS Bottle - CTD Changed QUALT2 to: Salt Oxygen 890/1/1 2195.7db No Btl S, No Btl o2 CTDOXY 4 /2 2195.2 No CTD S, No CTD o2 Smp1 - Smp2 ok 51.8 UMOL/KG 900/1/10 298.9 2.93 PSU ok CTDSAL 4 /11 273.4 0.36 ok CTDSAL 4 /12 248.6 0.24 ok CTDSAL 4 /13 224.1 0.24 ok CTDSAL 4 901/1/6 1002.3 1.02 ok CTDSAL 4 /7 903.2 0.26 ok CTDSAL 4 /8 808.0 1.08 ok CTDSAL 4 /11 498.1 1.04 ok CTDSAL 4 /12 403.9 1.02 ok CTDSAL 4 /14 253.4 1.48 ok CTDSAL 4 902/1/4 1799.4 1.25 ok CTDSAL 4 No changes were made to quality flags of other parameters for these samples but conversions from /liter to /kg are suspect. 9. Made new exchange file for Bottle data. 10. Checked new bottle file with Java Ocean Atlas. DATE CONTACT DATA TYPE ACTION SUMMARY ---------- ------------ --------------------- ----------------------------------------- 2004-02-13 Anderson CTD WOCE formatted/Online Sharon Escher noted that the value in the RECORDS= field was sometimes incorrect. In checking this I discovered that almost every station had ^Z as the last record. A few stations also had a record at the end that just had zeros except for the QUALT1 field, which had values. I deleted these records and corrected the value in the RECORDS= field when necessary. Station 899 data between 4583.0 and 4653.0db was repeated at the end. I deleted the duplicate levels. Station 941 had a date of 092295 in the ctd file, and 092395 in the.sum file. I changed the ctd file to agree with the sum file. Oxygen was in ml/l. I converted to umol/kg. Station 870 and 871 had negative oxygens that I changed to 0.00 re J. Swift. PRESS OXYGEN Sta. 870 25.0 -0.407 27.0 -0.439 29.0 -0.236 Sta. 871 33.0 -0.260 Changed file names from xxx.CTD to i01wxxxx.wct. Had to remove COR DEPTH from .sum header in order to get the exchange program to work. 2005-01-10 Key Cruise Report C14 Report Submitted The U.S. WOCE Indian Ocean Survey consisted of 9 cruises covering the period December 1,1994 to January 22,1996.All of the cruises used the R/V Knorr operated by the Woods Hole Oceanographic Institute. A total of 1244 hydrographic stations were occupied with radiocarbon sampling on 366 stations. 2005-02-18 Anderson HELIUM/NEON Data online i01e and i01w Found file i1he.txt in .../indian/i01/i01/original/2000.10.04_I1_BOTTLE. This file contains the deep DELHE3, HELIUM, NEON, DELHER, HELIER, and NEONER for i01e and i01w. I merged these parameters into the online files, and made new exchangeand netcdf files. There were no Q1 or Q2 flags so I set them to 2. 2005-05-06 Anderson CTD sta 882 O2 changed to µmol/kg As noted by Sharon Escher, sta. 882 was missing from the ctd stations. I converted the oxygen to umol/kg on sta 882, added it to the ctd .zip file, made new exchange and netcdf files and put all files online. 2005-05-11 Reid NUTs Update Needed, various anomolies I've finally had a chance to look at the Indian Ocean (I1W) data. We noted in our cruise report that Niskin 7 at Stn 910 was an obvious leaker and that the nutrients were flagged as 4. I'm pretty sure that's the 3793 dbar bottle. I don't know why the nutrients aren't flagged, as my notes say they were. Re the odd deep nutrients at Stn 859: The original at-sea calculation of those nutrients was made incorrectly, using the wrong values for the standard concentrations. They were recalculated post-cruise and look as though they will fit within the envelopes of the property plots from the other Red Sea stations. Again, I don't know why the corrected version wasn't part of the final data set. I will dig out or create a digital version of stn 859 and send it to you, hopefully before the end of the week. 2005-05-11 Reid NUTs Follow-up on previous note I found our Zipped data files and will attach a text file with the data from I1W Stn 859. The nutrient data matches the paper listing of the recalculated version that I found yesterday. Could you let us know if this version agrees with the other Red Sea data? (It looks like it will.) Once I hear from you, I'll send the correct data to the WHPO and others. 2005-06-13 Anderson NUTs WOCE/Exchange/NetCDF files onlie i01w 316N145_11 Made changes to SILCAT, NITRAT, NITRIT, and PHSPHT on sta. 859 re Joe Jennings. Put corrected file online, made new exchange and netcdf files. 2008-06-17 Kappa Cruise Report Added C14 & CO2 reports & Data Processing Notes Added these WOCE/CCHDO Data Processing Notes Added 4 reports to pdf and text versions of cruise report: 1) Carbon Dioxide, Hydrographic and Chemical Data 2) Coulometric Total Carbon Dioxide Analysis 3) Assessment of the Quality of the Shipboard Measurements of Total Alkalinity 4) Anthropogenic CO2 Inventory 5) U.S. Woce Indian Ocean Survey: Final Report for Radiocarbon