If symbols do not display correctly change your browser character encoding to unicode CRUISE REPORT: SR04 (Updated OCT 2013) HIGHLIGHTS CRUISE SUMMARY INFORMATION WOCE Section Designation SR04 Expedition designation (ExpoCodes) 06AQANTIX_2 Chief Scientists Eberhard Fahrbach / AWI Dates 1990 NOV 17 - 1990 DEC 30 Ship POLARSTERN Ports of call Punta Arenas, Chile - Cape Town, S. Africa 54°19'59" S Geographic Boundaries 58°53'12" W 3°20'42" W 71°6'47" S Stations 82 Floats and drifters deployed 0 Moorings deployed or recovered 21 deployed, 7 recovered Contact Information: Eberhard Fahrbach Alfrd Wegener Institut für Polar und Meeresforschung D-2850 Bremerhaven, F.R. • Germany Tel: 49-471-4831-501 • Fax: 49-471-4831-149 49-471-4831-425 Email: efahrbach@awi.bremerhaven.de FOREWORD V.Smetacek, U. Bathmann (AWI) The ninth research cruise of RV "Polarstern" to the Antarctic (ANT IX) consisted of 4 Legs. The first Leg addressed chemical interactions between ocean and atmosphere during the southward voyage. The second Leg carried out investigations of the Weddell Gyre within the framework of the World Ocean Circulation Experiment (WOCE). The third Leg was planned as a broad-based, interdisciplinary study of the hitherto unexplored southwestern Weddell Sea but had to be reorganized with a new scientific program for the Lazarev Sea because of exceptionally heavy ice conditions in the Weddell Sea. The fourth Leg was the return journey and was primarily devoted to the geology of the South Atlantic. RV "Polarstern" departed from Bremerhaven on October 20, 1990 and arrived in Punta Arenas on November 14. The intensive chemical research Programme was a continuation of previous Atlantic crossings and addressed hemispheric variability of metals and various natural and anthropogenic compounds in atmosphere and ocean. The second Leg commenced on November 17 and proceeded first to King George Island where personnel and supplies were dropped off at the Bellingshausen station. From there, the transect across the Weddell Gyre first performed in the winter of 1989, was repeated. Twenty one current meter moorings were deployed and the 7 in the field since 1989 were successfully recovered and equipped with new Instruments. Water column measurements of physical, chemical and biological parameters were carried out; the data will aid in assessing seasonal differences in hydrography and their influence on the ecology of the Gyre. The current meter data will enable quantification of bottom water formation and transport of water out of and into the Gyre. Sediment traps attached to three of the current meter moorings were also serviced. The data obtained from them, together with results of specific studies on silica cycling, will further our knowledge on vertical particle flux and cycling of matter in the Weddell Sea. At the end of the cruise, equipment was dropped at the Georg-von-Neumeyer Station (GvN). Cape Town was reached on December 30, 1990. The third leg left Cape Town on January 3, 1991 with personnel and equipment for GvN On board. Shortly after disembarkation and unloading of supplies at GvN, "Polarstern" helicopters rescued 5 South-African personnel who were stranded at 3,000 m elevation and 300 km inland. The unusually heavy and extensive ice cover prevented "Polarstern"'s southward journey and the ship was forced to drift for 2 weeks entrapped in thick, soft ice named "porridge ice" by Capt. Lawrence of RRS "Bransfield". Ice and under-ice physics and biology were investigated during the period of drift, and as ice conditions did not irnprove till the beginning of February alternate plans had to be made for work in the Lazarev Sea between GvN and Georg-Forster stations. On several transects along the shelf and into the deep-sea, all disciplines participating on this cruise - oceanography, biology and geology - investigated in closely interlocked programmes water rnass distribution, water chemistry as well as the morphology of the sea floor and cornposition of the sediments. GvN was visited on the return journey and personnel from here as well as the Georg-Forster-Station further to the East transported to Cape Town where "Polarstern" arrived on March 28, 1991. The fourth Leg departed from Cape Town on March 30 and proceeded to Bouvet Island. The aim of this predorninantly geological Leg was to rnap and sample submarine elevations - the Agulhas Ridge, the Meteor Rise and the eastern flank of the southernrnost Mid-Atlantic Ridge - in order to refine existing models of the paleoceanography of the South Atlantic. "Polarstern" arrived in Brernerhaven on May 13, 1991. 1. ITINERARY AND SUMMARY E. Fahrbach (AWI) On 17 November 1990 "Polarstern" left Punta Arenas. In Drake Passage physical oceanography work was started with an XBT-transect (Expendable Bathythermograph) across the Antarctic Circumpolar Current. An Acoustic Doppler Current Profiler (ADCP) recorded the current field in the upper few hundred meters. The bathymetry and geology Programmes began with soundings of Hydrosweep and Parasound which were continued during the complete cruise. Chemical investigations from the first leg were continued with underway measurements. They concentrated on biogenic sulfur compounds and their reaction products in sea water and the marine atmosphere with particular interest in DMS (dimethyl sulfide). Concentrations of nitric acid, ammonia and ammonium nitrate and organobromine compounds were investigated in the marine atmosphere. We reached the Polar Front on 19 November at 57°23'S, 61°14'W. The first logistic task of the cruise was to deposit three German scientists with more than 8 tons of supply goods at the Soviet station "Bellingshausen" on King George Island. One scientist returned with us after an eleven months stay. After measuring the first CTD-profile (conductivity, temperature, depth) and making a catch with the multinet, we approached Joinville Island at the northeastern tip of the Antarctic Peninsula. There, two hauls with the Agassiz-trawl provided material for comparative studies on the temperature dependence and kinetics of digestive enzymes in crustaceans. Still in open water we reached the western end of our main hydrographic transect crossing the Weddell Gyre towards Kapp Norvegia (Figure 2.1) where the first of 21 current meter moorings was deployed and the first of seven recovered. On the shelf the first biology station took place including measurements with quantameter and Secchi disk, two CTD casts combined with a rosette water sampler and catches with multinet, bongo net, and plankton net. The water samples were used for biogeochemical investigations with special emphasis on the silica and nitrogen cycles. For this reason incubations were carried out to measure the uptake of radioactive 14C, 32Si and 32P and stable 15N. The nitrogen flux in the Antarctic food web could be determined from the water column to the zooplankton. In this context the phytoplankton biomass and species distribution as well as reproduction and life cycles of dominant copepods were studied. On 22 November at about 150 km from the coast we met at 63°30'S, 51°30'W the ice edge. The winds calmed down with increasing distance from the coast and air temperatures did not drop below -4°C. Rather quickly the swell disappeared and the floes increased in size. However, due to a system of leads, we could proceed along our course as planned. On 26 November at 65°34'S, 38°52'W we reached a deep sea channel which was surveyed with hydrosweep and parasound along 500-km profiles over a distance of 144 km. The structure is 1 to 3 km wide with a depth of 60 to 100 m below the adjacent sea level of about 4650 m. It extends with large meanders from westnorthwest to eastnortheast. Due to the heavy ice cover, consisting of floes a few kilometers in diameter and up to a meter thick, the track line could not be maintained as straight as desirable. Bottom samples were collected with a minicorer which was hung under the CTD. This instrument was newly developed. During initial trials a procedure was achieved which allowed its use without significant additional shiptime. After this phase it was used routinely on 37 stations. The first recovery of a current meter mooring (208) within the ice (70% ice cover) occurred on 29 November. Before the acoustic release of the mooring the floes of up to 500 m in diameter were broken into smaller pieces to allow the floats to reach the surface. After the release 40 minutes of intensive search were necessary to sight a float before the recovery could be successfully finished. At mooring 209 on 3 December no float reached the surface and a time consuming acoustic ranging and breaking of ice floes finally permitted the detection and consequent recovery after 8 hours. This tedious technique had to be applied during all further recoveries, whereas the deployment of moorings could be accomplished without any problem. Figure 2.1: Cruise track of "Polarstern" during ANT IX/2 The center of the Weddell Gyre at about 66°16'S, 30°18' is marked by a relatively shallow surface mixed layer. It was reached on 2 December. For a better localization of the center a transect of 150 nm length consisting of 7 CTD-stations perpendicular to the main transect was carried out. On the basis of those data absolute velocities will be determined using the Beta spiral concept. During the Winter Weddell Gyre Study (WWGS) '89 higher mixed layer temperatures and more intense biological activity were found in that area. This was not observed during the present cruise possibly due to the different season. On 7 December the investigations in the "beta cross" area were terminated and the main transect was continued to the southeast with CTD- profiles, biology stations, mooring recoveries and deployments. The ice conditions became less favourable due to larger floes of less friable ice and closed leads because of colder temperatures. The transect was finished on 15 December. The coastal polynya was only poorly established and highly variable. Because the biologists noted that there was no sign of a spring bloom, the planned stations were cancelled. The desert-like conditions in the water column, evidenced by a Secchi depth of 54 m were in sharp contrast to the abundant algae growth in the ice which gave rise to all coulors from yellow to brown. Although small the narrow polynya was large enough for a haul with the Agassiz-trawl. The offshore ice belt of the polynya confirmed the term "icefactory". It provided the heaviest ice conditions during the cruise and made the recovery of mooring 214 impossible. The last station on the transect was located in an inlet of 1 km length and 400 m width. In this inlet casts with CTD, multi- and bongo net were carried out in Open water in the vicinity of the 25 m high shelf ice front. After a hydrosweep survey of the continental slope in the area of the Explorer-Escarpment we left On 16 December towards the Georgvon- Neumayer-Station (GvN). The work along the transect between Joinville Island and Kapp Norvegia amounted to 82 CTD and rosette stations, 7 biology stations, 21 mooring deployments and 7 recoveries. The established mooring network represents a gigantic flow meter which measures the volume of water and its heat content entering the Weddell Gyre in the northeast and leaving it in the northwest. South of our transect, cooling due to contact with the atmosphere and the shelf ice, together with salt release through ice formation, induces vertical descent of water masses to the bottom. Glacial meltwater has to be taken into account for a quantitative understanding of those processes. Because of the significance of deep reaching vertical mixing for the global abyssal circulation, our measurements are part of the World Ocean Circulation Experiment (WOCE). The biogeochemical investigations of the cycles and budgets of various constituents represent a contribution to the international Joint Global Ocean Flux Study (JGOFS). They aim to explain the special role of the Weddell Gyre in the Southern Ocean and to estimate the significance of this area to the global carbon cycle. The contrast between the high nutrient availability and the low production remains unresolved. A chemical-biological project allowed for the first time, direct measurement of DMS-production of Antarctic phytoplankton and determination of the contributions of different species. On 17 December we reached Atka-Bight. In the early morning "Polarstern" rammed into the fast ice to provide a safe platform for the unloading of about 100 tons of supply goods for the GvN-Station. First contacts with the female overwintering team had been established by a helicopter visit on 13 December to prepare the unloading procedure. The first trek with unloaded material left in the early afternoon towards the shelf ice edge and the station. Due to favourable conditions all loading was finished in the evening. "Polarstern" left the Atka-Bight at midnight of 18 December. On the way north air chemistry, XBT, hydrosweep and parasound measurements were continued. The ice edge was met at 68°00'S, 3°58'W where the ice concentration dropped within 30 nm from 70% to 10%. Here the last biology station was carried out. On 23 December we reached 54°20'S, 3°23'W about 200 nm west of Bouvet Island were mooring BO1 was deployed with two sediment traps. The Polar Front was crossed on 24 December at 51°45'S 2°24'E. Christmas Eve was celebrated with a merry ceremony in the "Blue Saloon" and a delightful buffet. The recovery of the last mooring PF3 and deployment of PF4 was achieved in the morning of the 25 December. When we reached the 200 nm limit research was terminated. On 30 December 1990 at 01.00 "Polarstern" reached the bunker pier of Cape Town. Cruise Participants Name Institution* ---------------------------- ------------ Baumann, Marcus AWI Behmann, Thomas AWI Bluszcz, Thäddaus AWI Brandini, Frederico AWI Brosin, Hans-Jürgen IfMW Buxhoeveden, Cristina Isabel ITBA Corradi, Pio Ante AF Dehn, Joachim AWI Dittrich, Birgit AWI Erdmann, Holger DWD Frhrback, Eberhard AWI Goeyens, Leo VUB Goldkamp, Ulrich AWI Harder, Markus FPB Heitmüller, Karl-Heinz HSW Hillebrandt, Oliver HSW Hinrichsen, Hans-Harald FPB Knoche, Martin AWI Köhler, Herbert DWD Krest, Jim OSU Kubrjeweit, Frank AWI Lengacher, Dieter AF Leynaert, Ande IEM Lindenmaier, Patrick AF Lindner, Louis RUU Markus, Thorsten AWI Monk, Jürgen AWI Papenbrock, Thomas RUB Pauls, Margarete AWI Pfeiffenberger-PertI, Hans AWI Plugge, Rainer AWI Quéguiner, Bernard IEM Ragueneau, Olivio IEM Rauschert, Martin FiW to K.G.I Riewesell, Christian HSW Ross, Andy OSU Schäfer, Hartmut FPB Schlumpf, Hans-Ulrich AF Schmidt, Martin IfMW Schoch, Roland FPB Schöffmann, Erhard FGB Schrerns, Otto AWI Schütt, Ekkehard FPB Segl, Monika FGB Simon, Bernd FiW to K.G.I Sonnabend, Hartrnut DWD Staubes, Regina IfMG Sterr, Uta FPB Stiller, Michael AWI to K.G.I Strass, Volker AWI Tins, Wolfgang TA Vucelic, Sonja AWI Wasserthal, Claus HSW Weber, Michael AWI Wisotzki, Andreas FPB Zippel, Detlev FiW from K.G.I List of Institutions Abbreviation Institution ------------ -------------------------------------------- AWI Alfred-Wegener-Institut für Polar- und Meeresforschung Columbusstrasse 2850 Bremerhaven Germany DWD Deutscher Wetterdienst Seewetteramt Bernhard-Nocht-Str. 76 2000 Hamburg 4 Germany FGB Universität Bremen Fachbereich Geowissenschaften FB5 Postfach 33 04 40 2800 Bremen 33 Germany FiW Forschungsstelle für Wirbeltierforschung Alfred-Kowalke-Str. 17 O-1136 Berlin Germany FPB Universität Bremen Fachbereich Physik FB1 Postfach 33 04 40 2800 Bremen 33 Germany HSW Helicopter-Service Wasserthal GmbH Kätnerweg 43 2000 Hamburg 65 Germany IfMG Johann Wolfgang Goethe-Universität Institut für Meteorologie und Geophysik Feldbergstr. 47 Postfach 11 19 32 6000 Frankfurt am Main 11 Germany IfMW Institut für Meereskunde Akademie der Wissenschaften der DDR Seestr. 15 O-2530 Rostock-Warnemünde Germany RUB Ruhr-Universität Bochum Fakultät für Chemie / Physikalische Chemie I Postfach 10 21 48 4630 Bochum 1 Germany TA TERRAQUA Indersdorfer Str. 16 8061 Arnbach Germany ITBA Instituto Technologico de Buenos Aies Avda Enardo Madero 351/99 1106 Buenos Aires Argentina VUB Vrije Universiteit Brussels Laboratory for Analytical Chemistry Pleinlaan 2 B-1050 Brussels Belgium CBM Centro de Biologia Marinha/UFPR AV. Beira Mar, Ponta do Sul Paranagua 83200 Pr Brazil IEM Institut d'Etudes Marines Université de Bretagne Occidentale 6 Avenue le Gorgeu F-29287 Brest Cedex France RUU Rijksuniversiteit te Utrecht Faculteit der natuur en sterrenkunde Princetonplein 5 NL-3508 TA Utrecht Netherlands AF Arian Film AG Postfach 835 CH-8025 Zürich Switzerland OSU Oregon State University College of Oceanography Oceanography Administration Building 104 Corvallis, Oregon 97331-5503 2. PHYSICAL OCEANOGRAPHY 2.1. Water masses and circulation T. Behmann, E. Fahrbach, J. Dehn, M. Knoche, T. Markus, R. Plugge, V. Strass (AWI), C. Buxhoeveden (ITBA), M. Harder, H.-H. Hinrichsen, H. Schäfer, U. Sterr, A. Wisotzki (FPB); E. Schütt (FGB), H.-J. Brosin, M. Schmidt (IfMW) Objectives The aim of the physical oceanography programme is to further understand the circulation in the Weddell Gyre and the related distribution of water masses. The operations contribute to a multiyear project, the Weddell Gyre Study, which is part of the World Ocean Circulation Experiment (WOCE). During this period a hydrographic survey along a transect from the northern tip of the Antarctic Peninsula to Kapp Norvegia (Figure 2.2) will be repeated four times, twice in summer and twice in winter, to measure the water mass distribution with its seasonal and interannual variability. The programme was initiated with a winter survey in 1989, the Winter Weddell Gyre Study (WWGS) '89, and will be continued with further surveys in austral winter 1992 and summer 1992/1993. Figure 2.2: Schematic representation of the Weddell Gyre and the transect from Joinville Island to Kapp Norvegia (KN). Simultaneously an extensive current meter mooring programme began with the deployment of seven current meter moorings. The data from those moorings will be used to estimate the volume transport in the Weddell Gyre. Direct current measurements are essential because they are the only way to obtain the barotropic flow which determines the net volume transport. From the measured mass, heat, and salt transports across the transect we can derive water mass formation rates. The transformation of Winter Water (WW) and Warm Deep Water (WDW) in the inflow to Antarctic and Weddell Sea Bottom Water (AABW, WSBW) in the outflow is of special interest, because it results from a deep vertical exchange which is relevant to the large scale abyssal circulation of the world ocean. Present estimates show that about 70% of the Antarctic Bottom Water spreading into the world ocean obtains its water mass characteristics in the Weddell Sea. Because the salt budget of the area is strongly influenced by ice formation and melting, special interest is focused on the ice transport across the transect. Interaction with the ice shelves has to be taken into account for a quantitative understanding. Figure 2.3: Station map of "Polarstern"-cruise ANT IX/2. Small dots stand for CTD-stations, circles for recovered and Squares for deployed moorings. Work at sea In order to obtain the water mass distribution, a hydrographic section was carried out with 74 CTD-profiles (conductivity, temperature, depth) and discrete casts for temperature, salinity, oxygen, nutrients and tracers (helium, tritium and (^18)O). For the location of the stations see Figure 2.3 and the station list. On the eastern slope the station distance was small enough (Figure 2.4) to resolve topographic features such as the Explorer-Escarpment Seven current meter moorings were recovered and 21 were laid (Table 2.1 and 2.2, Figure 2.3). On six of them ice thickness will be measured by upward-looking Sonars (ULS). The moorings will stay in position for two years. Vertical temperature and electrical conductivity profiles were measured with a Neil Brown Mark III B CTD. The quality of the CTD-measurements was assured by reference measurements with a rosette sampler. Water samples were taken with a General Oceanic rosette composed of 24 bottles with 12 l volume each. Each time a water bottle was closed 50 cycles of pressure, temperature and conductivity were recorded with the CTD, quality controlled and averaged. Figure 2.4: Cruise-track and location of CTD-stations off Kapp Norvegia during "Polarstern"-cruise ANT IX/2. Pressure and temperature measurements were corrected by means of a laboratory calibration carried out in the Scripps Institution of Oceanography before the cruise. A second calibration will be done after the cruise. Both calibrations will lead to a more elaborate correction of the data. However, the control by electronic as well as mercury reversing thermometers and pressure meters gives us confidence that the preliminary data have errors of less than 5 mK in temperature and 5 db in pressure. The salinity data are given in PSU. They are based on the CTD conductivity measurements from which salinity was calculated using the Unesco Practical Salinity Scale (PSS78). The values were compared with salinities from water bottle samples measured with a Guildline Autosal 8400 A in reference to I.A.P.S.O. Standard Seawater. The number of samples per profile, the mean difference between the samples and the CTD measurements as well as its standard deviation are shown in Figure 2.5. Preliminary data presented in this report were corrected with a constant offset of 0.023 to an accuracy of 0.005. The final data will be corrected in conductivity for time and depth dependence of the deviations. Afterwards salinity will be recalculated. Figure 2.5: Comparison between salinity measurements from water bottles with those from the CTD. Stars give the mean difference for each station between the bottle and CTD salinities, squares the standard deviation, and dots the number of samples per station. Oxygen was determined with an automatic titration unit, using the Winkler method with a photometric endpoint determination. The error in the oxygen determination is estimated to 1%. This results from intercomparisons at selected stations between the chemical oceanography group from the Oregon State University and the AWI group both using different instruments. Duplicate samples from the same water bottle were analysed during the complete cruise as a measure of precision. The obtained data are given in ml/l. Table 2.1: Moorings recovered during "Polarstern"-cruise ANT IX/2 Mooring Latitude Date Water Depth Instrument Longitude Time (m,corr.) Type Depth ------- ----------- -------- ----------- ---- ----- 206 63°29.6' S 13.09.89 946 AVT 229 52°07.4' W 11.13 S 349 22.11.90 AVT 876 08.52 207 63°45.8' S 14.09.89 2503 AVTPC 263 50°54.3' W 10.39 AVTPC 952 23.11.90 AVT 2162 00.41 AVT 2410 208 65°36.3' S 24.09.89 4768 AVTPC 288 36°29.9' W 18.30 AVTPC 1037 29.11.90 S 1090 13.00 (AVT) 2610 S 4122 AVT 4631 209 66°36.8' S 01.10.89 4863 AVTC 293 27°07.4' W 10.28 AVTPC 993 03.12.90 (AVT) 2653 09.16 (AVT) 4725 210 69°38.9' S 05.10.89 4751 AVTC 289 15°44.5' W 21.11 AVTPC 988 11.12.90 AVT 2547 14.29 AVT 4617 211 70°29.5' S 6./7.10.89 2402 AVTC 247 13°07.0' W 00.13 AVTPC 856 14.12.90 AVT 2066 14.28 AVT 2313 212 70°59.2' S 08.10.89 1069 AVTPC 309 11°49.4' W 16.55 AVT 999 13.12.90 22.50 PF3 50°07.6' S 09.11.89 3785 S 625 05°50.0' E 10.34 AVT 645 25.1 2.90 S 3200 08.30 AVT 3220 AVTPC: Aanderaa current meter with temperature, pressure and conductivity sensor. In brackets instruments with poor data quality. S: Sediment trap Table 2.2: Moorings deployed during "Polarstern"-cruise ANT IX/2. Mooring Latitude (S) Date Water depth Type Instrument Longitude (W) Time (m,uncorr.) No. Depth ------- ------------- -------- ----------- ----- ------ ----- 215 63°19.89' 21.11.90 448 AVTP 10001 291 52°59.07' 20:14 AVTP 9996 396 WLR 1155 447 206/2 63°29.55' 22.11.90 942 AVTP 8402 253 52°06.27' 14:54 AVTP 9786 891 207/2 63°45.05 23.11.90 2498 ULS 9/90 165 50°54.32' 06:52 AVTP 9206 326 TK 1569 ATR 1100 578 AVTPC 8395 1037 AVT 8417 2187 TK 1570 ATR 1102 2439 AVT 8418 2447 216 63°56.96' 24.11.90 3477 AVT 9182 2968 49°09.21 00:34 AVT 9184 3426 217 64°25.10' 24.11.90 4424 ULS 13/90 141 45°50.97' 21:26 AVTPC 9192 250 S 890107 796 AVTC 9211 1010 AVT 9185 2510 ACM-2 1281 4373 218 64°48.87' 25.11.90 4688 AVTP 10005 252 42°29.28 21:15 TK 1427 ATR 944 505 AVTP 9212 993 AVT 9186 2503 ACM-2 1284 4636 219 65°39.87' 28.11.90 4732 AVT 9187 4226 37°42.45' 13:36 AVT 9188 4674 AVT 9190 4722 208/2 65°38.14' 29.11.90 4776 ULS 11/90 171 36°30.20' 18:27 AVTPC 9194 281 AVTPC 9213 1040 S 890106 1123 AVT 9191 2533 S 890108 4165 ACM-2 1285 4725 220 65°58.19' 30.11.90 4799 AVT 9767 4300 33°20.33' 15:43 AVT 9768 4748 221 66°16.63' 02.12.90 4784 ADCP 236 30°17.78' 10:49 AVTPC 9195 247 TK 1426 ATR 943 499 AVTPC 9214 985 AVTPC 9215 2499 ACM-2 1288 4732 209/2 66°37.35' 03.12.90 4862 ULS 14/90 147 27°07.10' 20:50 AVTP 9202 279 AVTPC 9216 1015 AVTPC 9217 2526 ACM-2 1289 4809 222 67°03.56' 07.12.90 4836 AVT 9769 4336 24°52.11' 22:54 ACM-2 1282 4785 223 67°59.84' 09.1 2.90 4885 AVTPC 9205 251 19°57.64' 17:24 AVTPC 9218 1010 AVT 9208 2520 ACM-2 1290 4834 224 68°49.65' 10.12.90 4740 AVT 9770 4239 17°54.49' 13:38 ACM-2 1291 4689 210/2 69°39.63' 11.12.90 4745 ULS 10/90 151 15°42.90' 16:50 AVTP 9201 270 TK 1571 ATR 1103 523 AVTP 9995 1012 AVT 9391 2521 ACM-2 1297 4694 225 70°19.11' 12.12.90 4329 AVTP 10002 275 13°39.61' 18:19 AVT 9783 1124 AVT 9997 2625 AVT 9782 4278 226 70°22.84 13.12.90 2943 AVTP 10003 231 13°32.53 00:57 AVTP 9998 980 AVT 9207 2892 212/2 70°54.67' 14.12.90 1555 ULS 12/90 135 11°57.80' 07:34 AVTP 8367 254 AVTC 9401 759 AVT 9402 1504 211/2 70°29.67' 14.12.90 2381 AVTP 10004 270 13°08.85' 22:17 TK 1572 ATR 1104 523 AVTP 8396 1012 AVT 9999 2222 AVT 9392 2329 KN4 70°59.51' 15.12.90 892 S 860019 328 11°46.86' 09:55 AVTP 9209 333 S 860020 782 AVTPC 9210 810 UCM 811 214/2 71°02.93' 15.12.90 378 AVTP 8370 213 11°41.25' 12:56 AVT 9403 318 WLR 1044 377 BO1 54°20.3' S 23.12.90 2734 S 860024 423 03°22.6' W 16.43 AVT 7727 474 S 890005 2196 AVT 8037 2217 PF4 50°07.6' S 25.12.90 3807 S 860038 625 05°52.0' E 10.31 AVT 9803 646 S 890009 3267 AVT 9805 3290 Abbreviations: ACM-2 Acoustic current meter, Neil Brown ADCP Acoustic doppler current meter ATR Recording unit for thermistor chain AVTPC Aanderaa current meter with temperature.pressure and conductivity sensor S Sediment trap UCM Acoustic current meter, Simtronics ULS Upward looking sonar WLR Water level recorder 2.2. CTD Measurements CTD Measurements during AQANTIX/2 Instrument : Neil Brown CTD, Mark IIIB, Sn: 1069, BJ: 1984 CTD temperature sensor : Rosemount Platinum Thermometer resolution : 0.0005 deg C accuracy : +/- 0.005 deg C CTD pressure sensor : Paine Model resolution : 0.1 dbar accuracy : +/- 6.5 dbar CTD conductivity sensor : EG&G NBIS resolution : 0.001 mmho accuracy : +/- 0.005 mmho Software : EG&G Oceansoft MkIII/SCTD Aquisition Version 2.01 CTD postprocessing Version 1.12 Time lag : 0.13 s Pressure pre-cruise calibration coefficients a1 = -1.1552376e+1 a2 = 7.014388e-3 a3 = -1.236572e-5 a4 = 7.641595e-9 a5 = -2.052136e-12 a6 = 2.544142e-16 dp = a1 +a2*p +a3*p**2 +a4*p**3 +a5*p**4 +a6*p**5 p = p + dp Temperature pre-cruise calibration coefficients a1 = -2.99299 a2 = -7.18462e-4 a3 = 4.44174e-5 a4 = -1.43668e-6 a5 = 2.67305e-8 dt = a1 +a2*t +a3*t**2 +a4*t**3 +a5*t**4 t = t + dt the post-cruise calibration data are the same correction of the CTD-conductivity data with the bottle-samples ( conductivity of the salinometer data ) evaluation of the coefficients of each station -------------------------------------- CD = ( CONDUCTIVITY SALINO - CONDUCTIVITY CTD ) * 1000 COND :== CONDUCTIVITY SALINOMETER -------------------------------------- CD = A0 + A1*COND + A2*PRES + A3*PRES**2 -------------------------------------- station no. A0 A1 A2 A3 03501 -0.51872E+02 0.24728E+01 -0.63940E-02 0.79995E-05 03601 -0.51872E+02 0.24728E+01 -0.63940E-02 0.79995E-05 03901 -0.51872E+02 0.24728E+01 -0.63940E-02 0.79995E-05 04001 -0.51872E+02 0.24728E+01 -0.63940E-02 0.79995E-05 04101 -0.51872E+02 0.24728E+01 -0.63940E-02 0.79995E-05 04201 -0.59161E+02 0.26925E+01 -0.35827E-02 -0.59052E-05 dc = A0 + A1*COND + A2*PRES + A3*PRES**2 C(ctd) = C(ctd) + dc/1000. correction of the CTD-conductivity data with the bottle-samples evaluation of the coefficients with the running mean of 10 stations -------------------------------------- CD = A0 + A1*PRES + A2*PRES**2 + A3*PRES**3 + A4*PRES**4 -------------------------------------- station no. A0 A1 A2 A3 A4 4301 0.16057E+02 -0.53003E-02 0.36477E-05 -0.77356E-09 0.43815E-13 4401 0.16057E+02 -0.53003E-02 0.36477E-05 -0.77356E-09 0.43815E-13 4501 0.16057E+02 -0.53003E-02 0.36477E-05 -0.77356E-09 0.43815E-13 4601 0.16060E+02 -0.52277E-02 0.35370E-05 -0.75885E-09 0.44722E-13 4701 0.16060E+02 -0.52277E-02 0.35370E-05 -0.75885E-09 0.44722E-13 4801 0.16275E+02 -0.59179E-02 0.41748E-05 -0.97715E-09 0.69451E-13 4901 0.16108E+02 -0.60083E-02 0.49328E-05 -0.13678E-08 0.12189E-12 5001 0.16102E+02 -0.54978E-02 0.43413E-05 -0.11653E-08 0.99760E-13 5101 0.16899E+02 -0.77574E-02 0.66678E-05 -0.20257E-08 0.20231E-12 5201 0.16881E+02 -0.59944E-02 0.44888E-05 -0.13842E-08 0.14902E-12 5501 0.17761E+02 -0.70108E-02 0.56046E-05 -0.17661E-08 0.19017E-12 5601 0.17937E+02 -0.75108E-02 0.63627E-05 -0.20726E-08 0.22755E-12 5701 0.18022E+02 -0.64782E-02 0.53523E-05 -0.16870E-08 0.17910E-12 5801 0.18156E+02 -0.62368E-02 0.50660E-05 -0.15814E-08 0.16690E-12 5901 0.18156E+02 -0.62368E-02 0.50660E-05 -0.15814E-08 0.16690E-12 6001 0.18178E+02 -0.63440E-02 0.54099E-05 -0.17589E-08 0.19218E-12 6101 0.18370E+02 -0.59355E-02 0.48751E-05 -0.15619E-08 0.16985E-12 6201 0.18148E+02 -0.42419E-02 0.30712E-05 -0.86105E-09 0.82874E-13 6301 0.17937E+02 -0.26588E-02 0.15897E-05 -0.37211E-09 0.30423E-13 6401 0.17782E+02 -0.17227E-02 0.63312E-06 0.26379E-11 -0.17070E-13 6501 0.17723E+02 -0.12923E-02 0.25428E-06 0.12091E-09 -0.28589E-13 6601 0.17461E+02 -0.67162E-03 0.21007E-06 -0.21894E-10 0.11939E-14 6701 0.17694E+02 -0.13889E-02 0.65721E-06 -0.12674E-09 0.94644E-14 6801 0.17450E+02 -0.97850E-03 0.27286E-06 -0.15240E-10 -0.48745E-15 6901 0.17563E+02 -0.15356E-02 0.71896E-06 -0.15865E-09 0.15453E-13 7001 0.17563E+02 -0.15356E-02 0.71896E-06 -0.15865E-09 0.15453E-13 7101 0.17479E+02 -0.96447E-03 -0.73640E-07 0.16015E-09 -0.23761E-13 7201 0.17006E+02 -0.11719E-03 -0.62758E-06 0.27564E-09 -0.29867E-13 7301 0.16916E+02 -0.78963E-03 -0.29516E-07 0.39261E-10 -0.17887E-15 7401 0.16904E+02 -0.21073E-02 0.12650E-05 -0.40022E-09 0.48944E-13 7501 0.16726E+02 -0.18753E-02 0.10196E-05 -0.34344E-09 0.46267E-13 7601 0.16753E+02 -0.19489E-02 0.99166E-06 -0.30502E-09 0.39144E-13 7701 0.16940E+02 -0.26189E-02 0.15238E-05 -0.44051E-09 0.49389E-13 7801 0.16764E+02 -0.97997E-03 -0.79946E-08 0.76954E-10 -0.96646E-14 7901 0.16953E+02 -0.13147E-02 0.11905E-06 0.74029E-10 -0.12693E-13 8001 0.16250E+02 -0.28762E-03 -0.63608E-06 0.30982E-09 -0.38113E-13 8101 0.16592E+02 -0.93415E-03 -0.59756E-07 0.10940E-09 -0.14970E-13 8201 0.16592E+02 -0.93415E-03 -0.59756E-07 0.10940E-09 -0.14970E-13 8301 0.16971E+02 -0.19752E-02 0.84813E-06 -0.16722E-09 0.12449E-13 8401 0.17508E+02 -0.21779E-02 0.61323E-06 0.24780E-10 -0.18108E-13 8501 0.17608E+02 -0.13212E-02 -0.44565E-06 0.46132E-09 -0.74966E-13 8601 0.17806E+02 -0.95871E-03 -0.10371E-05 0.69309E-09 -0.10154E-12 8701 0.17901E+02 -0.50715E-03 -0.16823E-05 0.97189E-09 -0.13764E-12 8801 0.17782E+02 -0.15468E-03 -0.16149E-05 0.82369E-09 -0.10936E-12 8901 0.17752E+02 -0.12688E-02 -0.54494E-06 0.46368E-09 -0.68610E-13 9001 0.17595E+02 -0.44907E-03 -0.13521E-05 0.75085E-09 -0.10213E-12 9101 0.17818E+02 0.10371E-02 -0.27966E-05 0.12559E-08 -0.16210E-12 9201 0.17739E+02 0.92340E-03 -0.21876E-05 0.93502E-09 -0.11655E-12 9301 0.17696E+02 0.18375E-02 -0.32648E-05 0.13364E-08 -0.16358E-12 9401 0.17379E+02 0.36388E-02 -0.52546E-05 0.21307E-08 -0.26343E-12 9501 0.16627E+02 0.44116E-02 -0.55975E-05 0.21872E-08 -0.26592E-12 9601 0.16501E+02 0.44658E-02 -0.55051E-05 0.21473E-08 -0.26200E-12 9701 0.16684E+02 0.44739E-02 -0.55477E-05 0.21310E-08 -0.25597E-12 9801 0.17031E+02 0.31220E-02 -0.38486E-05 0.14558E-08 -0.17342E-12 9901 0.16900E+02 0.39229E-02 -0.47820E-05 0.17983E-08 -0.21271E-12 10001 0.16896E+02 0.38833E-02 -0.53216E-05 0.21346E-08 -0.26184E-12 10101 0.16874E+02 0.37733E-02 -0.54502E-05 0.22433E-08 -0.27886E-12 10201 0.16902E+02 0.37003E-02 -0.55233E-05 0.23019E-08 -0.28783E-12 10301 0.17029E+02 0.29472E-02 -0.48717E-05 0.21078E-08 -0.26871E-12 10401 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 10501 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 10601 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 10801 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 10802 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 10901 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 11301 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 11401 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 11402 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 11501 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 11502 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 12001 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 12101 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 12102 0.16995E+02 0.16188E-02 -0.32527E-05 0.15057E-08 -0.19816E-12 04502 0.16057E+02 -0.53003E-02 0.36477E-05 -0.77356E-09 0.43815E-13 04802 0.16275E+02 -0.59179E-02 0.41748E-05 -0.97715E-09 0.69451E-13 05602 0.17937E+02 -0.75108E-02 0.63627E-05 -0.20726E-08 0.22755E-12 06302 0.17937E+02 -0.26588E-02 0.15897E-05 -0.37211E-09 0.30423E-13 07502 0.16726E+02 -0.18753E-02 0.10196E-05 -0.34344E-09 0.46267E-13 09402 0.17379E+02 0.36388E-02 -0.52546E-05 0.21307E-08 -0.26343E-12 -------------------------------------- dc = A0 + A1*PRES + A2*PRES**2 + A3*PRES**3 + A4*PRES**4 C(ctd) = C(ctd) + dc/1000. -------------------------------------- CTD-Files column 5 : number = -9 :== unknown data , it was not possible to restore this data NOTES ON THE NUTRIENT DATA FILES FOR SWGS 90 (ANTIX/2) From: M. Consuelo Carbonell-Moore Joe C. Jennings, Jr. Louis I. Gordon STATIONS WITH MISSING NUTRIENTS: STATION MISSING NUTRIENT BOTTLE 040 NH4 ALL 043 PO4 3;13-16 044 NH4 1-4 046 NH4 ALL 062 NH4 3 066 NH4 14 067 PO4 6 067 N + N 6 072 PO4 ALL 073 PO4 5,6 075 N + N 14 078 Si(OH)4 10,11 083 NH4 ALL 084 PO4 ALL 087 N + N 4 087 NH4 1-8 090 N + N 6 090 NH4 4,6 091 PO4 ALL 092 PO4 ALL 092 NH4 4,7 093 NH4 21 096 PO4 18,19 098 NH4 ALL 099 NH4 ALL 105 PO4 ALL 106 PO4 ALL 106 NH4 1-4 115 PO4 ALL NOTES ON NITRITE (NO2) AND AMMONIUM (NH4): Because deep ocean nitrite and ammonium values are usually near the limit of detection, small shifts in baseline and/or blank levels can lead to the calculation of concentrations which are negative. Although these negative nitrite and ammonium values are physically impossible, we report them as an indication of the imprecision associated with the analysis. NOTES ON PHOSPHATE (PO4): Low phosphate values in stations 050 and 051 might be doubtful as there was and equipment change after station 049. Values at station 053 agree with those at station 049. There is a wide spread in deep phosphate values: 2.19 micromol/liter to 2.42 micromol/liter, many stations showing high values, higher than those from Wepolex and Ant V/2 cruises in the same region, but lower than WWGS 89. Deep phosphates increase in concentration from station 60 through station 83, increase which we can not account for. These high values might be an artefact from a change in blank values due to changes in either the deionized water or in the low nutrient seawater used to prepare standards. There is no information in the laboratory notebooks, logs or recorder charts that allows us to either correct or delete these data. However, they are of doubtful quality. The increase of phosphate values in these stations is 0.1 micromol/liter. Nitrate concentration values did not show the same trend. PRELIMINARY RESULTS The hydrographic features measured along the transect are presented as sections of potential temperature and salinity (Figure 2.6). Below a shallow surface layer of WW which deepens significantly towards the shelf edge, a temperature and salinity maximum due to the WDW is found. It is more pronounced at the boundaries than in the interior with temperatures up to 0.8% in the east and 0.4% in the west evidencing the inflow in the east and the outflow in the west. The largest part of the water column with potential temperatures between 0 and -0.8°C and salinities from 34.67 to 34.64 is classified as AABW. Below we find WSBW with temperatures colder than -0.8°C which extends in the West in a shallow layer over the continental slope indicating the outflow of this freshly formed water mass. The young age of this water mass is suggested by the high oxygen content (Figure 2.7). In the forthcoming analysis we will quantify the transformation which occurs south of our transect of inflowing water masses in the east into the outflowing ones in the west. Seasonal changes on that transect are most evident in the near surface layers. Relatively warm air temperatures (Figure 2.8 top) and weak winds (Figure 2.8 bottom) indicate the onset of spring. A comparison of surface layer temperatures and salinities measured in September and October during WWGS '89 with the ones obtained during the present cruise indicates a much more pronounced springtime warming in the west than in the east (Figure 2.9 top). The salinity decrease due to ice melting was more intense in the east than in the west (Figure 2.9 bottom). In the deeper layers fluctuations of a wide spectral range are expected to be at least as intense as the seasonal cycle. Consequently no seasonal change can be identified in the comparison of the two sections. From CTD data on a straight section only geostrophic current shear can be estimated. Absolute currents can be obtained by the use of mass conservation of geostrophic currents in and out of a closed area or by the Beta-spiral method. Therefore, in the area of the gyre centre, which is indicated by the doming of the isotherms, a second section normal to the main section was carried out with a length of about 275 km (Figure 2.10, top). The estimate of absolute geostrophic current velocities by use of the Beta-spiral method will yield additional information on the location of the gyre center complementary to the moored current meter data. However, this method requires the calculation of the second derivative of isopycnals with respect to horizontal and vertical coordinates and is very sensitive to fluctuations. Thus, quantitative estimates need to be carried out with the final data. The transects of the potential temperature along the Beta-cross (Figure 2.10, top) show smoothly inclined isolines which seem to reflect the doming of the Weddell Gyre. The temperature maximum of the WDW increases towards the north. This can be taken as an indication that there is a southward component in this level and consequently the center of the gyre has to be located further to the west. The interaction with the ice shelf was studied by means of a CTD profile which was measured in an inlet of the Quarisen northeast of Kapp Norvegia (Figure 2.1 1, top). The temperature profile shows cold WW above a slightly warmer layer centered at 200 m depth which tops a colder bottom layer (Figure 2.1 1, bottom). The salinity increases from top to bottom. Presently it is not possible to conclude if the deeper layer is the remnant of a WW-layer which reached to the bottom and is separated from a slightly warmed surface layer by an intrusion of warmer water from offshore, or if it represents water which emanates from under the ice shelf. Tracer data measured from the water samples will be used to answer this question. Figure 2.6: Vertical section of potential temperature (top) and salinity (bottom) from Joinville Island (left) to Kapp Norvegia (right) carried out during Polarstern"-cruise ANT IX/2. Figure 2.7: Vertical section of dissolved oxygen from Joinville Island (left) to Kapp Norvegia (right) carried out during "Polarstern"- cruise ANT IX/2. Figure 2.8: Three-hour averages of air temperature (top) and wind speed (bottom) measured during CTD-stations on "Polarstern" during ANT IX/2. Figure 2.9: Surface layer temperatures (top) and salinities (bottom) measured with the CTD in 10 m water depths during winter 1989 (WWGS '89, dotted line) and spring 1990 (ANT IX/2, solid line). Figure 2.10: Cruise track and station locations in the "Beta-cross" area during "Polarstern"-cruise ANT IX/2 (top) and vertical sections of potential temperature (bottom) along the track lines. Figure 2.11: Location of the station in the inlet of the Quarisen during "Polarstern"-cruise ANT IX/2 (top) and vertical profiles of potential temperature (stippled line) and salinity (solid line) in the inlet (bottom). 2.3. Distribution of dissolved inorganic nutrients in the water column J.M. Krest, A.A. ROSS (OSU) Objectives By obtaining high quality nutrient data from late winter and early spring, we will improve on the sparse historical data set of the central Weddell Sea. The repeated "Polarstern" transects should permit the seasonal and interannual variability of the major water masses to be assessed. This data set will be used to study the evolution of WW which is the mixed layer beneath the seasonal pack ice. WW properties change with length of time under the ice due to continuous mixing of warmer, higher nutrient waters (WDW) from just below the pycnocline. From the analysis of nutrients in this surface layer, we plan to extend and refine our earlier estimates of net primary productivity in the Weddell Sea. Work at sea At 88 CTD casts, water samples were taken and analyzed for silicic acid, phosphate (Ortho-Phosphate), nitrate + nitrite (N+N), nitrite, and ammonium. Analyses were performed using the ALPKEM RFA-300 continuous flow analysis System. The entire water column was sampled for nutrients, but at this time, only the surface water in the primary northwest-to-southeast transect has been examined for silicic acid, phosphate and N+N. Preliminary Results Contour plots of nutrients in the upper 500 meters (Figure 2.12) show a fairly well defined layer of WW from approximately 50°W to 14°W. In the WW-layer which occupies the top 100 meters of the water column silicic acid concentrations range from 70 to 80 µM, N+N concentrations from 28 to 30 µM, and phosphate concentrations from about 2.0 to 2.1 µM. Underlying this WW-layer is a reasonably strong nutricline, varying in depth from 100 to 150 meters. In this nutricline, silicic acid increases in concentration to 110 micromolar, N+N increases to 33 µM, and phosphate increases to 2.3 µM. For all three nutrients, concentrations are most elevated in the center of this gyre, indicating a general upwelling trend. At two locations, 40° and 32°W, the contour plots for all three nutrients indicate strong vertical mixing between the WW and the underlying water mass. At the Western and eastern boundaries, intense vertical mixing causes nearly vertical nutrient isolines. In the WSBW a tongue of low concentration silicic acid can be seen which extends laterally more than halfway across the Weddell Sea Basin at a depth of approximately 4500 to 5000 meters. Initial comparisons were made with data obtained by Oregon State University's group during WWGS '89 and show good agreement. Figure 2.12: Vertical sections of nutrients from Joinville Island to Kapp Norvegia carried out during "Polarstern'-cruise ANT IX/2. 2.4. Tritium and Helium measurements R. Well (FPB) Objectives Within the scope of the physical oceanography programme the tritium and helium-isotope contents of the water samples serve as tracers for water mass characteristics. In addition, they can yield information about the time scales of exchange of the water masses within the Weddell Gyre. On this cruise - for the first time - we degassed water samples at sea. This procedure is expected to reduce the contamination caused by longtime storage and can simplify the handling of the sample containers. For this purpose we tested new degassing equipment on board and will compare the results with those obtained with the traditional method. Work at sea We took water samples at 6 CTD-stations on the shelf and continental slope of the Antarctic Peninsula in water depths of about 400, 1000, 2200, 2500, 3550 and 4200 m, at 3 CTD-stations in the central Weddell Sea at water depths of about 4700, 4760 and 4860 m and at 4 CTD- stations on the eastern continental slope off Kapp Norvegia in water depths of about 4400, 2400, 1600 and 500 m. Altogether about 50 double-samples were taken. One half of them were degassed on board, the other half will be degassed after our return in the laboratory, the helium- and neon-isotope contents will be compared. Preliminary Results As the measurements of the samples have to be done with a mass spectrometer in the laboratory we can not present data or quantitative results of the intercomparison here. The degassing technique on board did not show serious technical problems. Some problems occurred with the melting off procedure of the glass ampoules so that presently we can not generally guarantee that the extracted gas is well caught in the glass ampoule. 2.5. Water level measurements C. Buxhoeveden (ITBA), E. Fahrbach, R. Plugge (AWI), E. Schütt Objectives Water level measurements and deployments of water level recorders were carried out during ANT IX/2 for two reasons: to obtain further information on the tides in the Weddell Sea and to study low frequency fluctuations such as coastal trapped waves or basin modes, for a better understanding of the fluctuations observed in the moored current meter records. Work at sea To obtain time series long enough for a detailed tidal analysis and to study lower period fluctuations, two current meter moorings on the western and the eastern shelf respectively (215, 214/2) were equipped with Aanderaa water level recorders (WLR). It was planned to recover mooring 214/1 with a WLR, but due to the heavy ice conditions off the eastern shelf, this was not possible and the mooring had to be recovered during the following leg. During the stay in the Atka-Bight a short period study took place to check a tidal prediction made by members of the Meeresphysik section at AWI on the basis of previous measurements. With this aim soundings of the navigational echo sounder were evaluated and a current meter was moored 50m below the hull of "Polarstern" through the moon pool (Figure 2.13). Preliminary results The short term study over 36 hours allowed us to compare the predicted and observed tidal range as well as the times of high and low water. It appears that they agree to the accuracy of the measurements. The times of the extrema can be determined to about 10 min which corresponds to the difference in the predictions. The determination of the tidal range is affected by the influence of lower period fluctuations of the sea level and the motion of the ship due to the unloading and later ballasting which changes the location and inclination of the echosounder. Both effects add up to an uncertainty of about 15 cm in the determination of the tidal range which is about 10% of the observed range. Within this range predicted and measured data correlate. The correlation between tidal current and sea level is less clear. Whereas during 18 December high and low water seems to correlate with maximum and minimum tidal current, on the 17th no correlation is found. This agrees with observations from moored current meters where nontidal current variability is as strong as the tidal one. Figure 2.13: Records of the current speed (open circles) in 50 m water depth and the navigational echo sounder from "Polarstern" during the visit to Atka-Bight. 2.6. Optical properties of sea water R. Plugge, V. Strass (AWI) Objectives The optical properties of sea water vary with its constituents of biological origin. Observational methods based on the variations of the optical properties allow measurements of biological variables at the same high sampling rate as temperature and salinity, and thus can be used for underway data recording. Data sets including both biological and physical variables collected in this way allow for statistical studies of the dependency of the biological realm on the physical environment. During the present cruise a sensor package for measuring temperature, salinity, chlorophyll, fluorescence, Mie backscatter and yellow substance was employed; the optical measurements allow determination of the concentration of phytoplankton biomass and particles and zooplankton concentration/activity. Work at sea The hydrographic-optical sensor package (named COMED, developed in the Meeresphysik section at the AWI) was mounted in the ship's well at hull depth (11 m), where the data were collected at a rate of 1 cycle per 10 seconds. Measurements were taken during two periods: the first starting on 18 November and ending on 22 November, the second period starting on 20 December and ending on 29 December. During both periods the ship crossed the Antarctic Circumpolar Current with the Polar Front: the first time on the southward leg from Punta Arenas towards Bellingshausen-Station, the second time on the northward leg from GvN- Station towards Cape Town. During the period in between the ice conditions required the COMED System to be switched off and to cover the sensor package with a protective lid in order to avoid damages. 2.7. Underway measurements of current profiles, XBTs and the thermosalinograph T. Behmann, J. Dehn, E. Fahrbach, M. Knoche, T. Markus, V. Strass (AWI), H.-J. Brosin, M. Schmidt (IfMW), C. Buxhoeveden (ITBA), M. Harder, H.-H. Hinrichsen, H. Schäfer U. Sterr, A. Wisotzki (FPB) Objectives The Antarctic Circumpolar Current is subject to a wide range of temporal and spatial variability. The repeated crossings of "Polarstern" are used to obtain a data set which is suitable to address longer term variability of the thermal field and spatial variability of the velocity field. The temperature profiles are inserted in the Integrated Global Ocean Services System (IGOSS). Work at sea This goal is approached by usage of the Vessel Mounted Acoustic Doppler Current Profiler (VM-ADCP, manufactured by RD Instruments, San Diego) which allows us to monitor the current profile in the upper 350m of the water column from the ship moving at full speed. The corresponding thermal structures were measured by means of XBTs using T-7 probes. Sea surface temperature and salinity is recorded by a thermosalinograph. By use of the ADCP a cross section of the upper ocean velocity profile through the Circumpolar Current was recorded through Drake Passage to the Antarctic Peninsula. A set of calibration data were collected by running a cross-shaped course pattern on the shelf of the Antarctic Peninsula. During the calibration courses the ADCP was operated in its bottom track mode; a variety of control parameter settings were used during the measurements in order to optimise the instrument's performance. The data sampled were transferred to the ship's VAX Computer for processing and plotting. During the measurements the ADCP was run without the occurrence of major problems. However, during a later phase of the cruise no more data were obtained for two reasons. First, in its mode of operation the ADCP's transducer sits at hull depth (approx. 11 m) in the ship's well without any protection against mechanical damage by ice floes pushed under the ship. When the ship moves through the ice the transducer is protected by a lid consisting of two stainless steel sheets of 8 mm thickness. With the transducer behind the protective lid the ADCP not able to function. Consequently, no ADCP measurements of current profiles could be obtained along the Weddell Sea cross section. Second, it appeared that the protective lid was not strong enough to withstand the collisions with ice floes. When we tried to reactivate the ADCP in ice-free waters after having left the GvN-Station, we noticed that the lid was deformed by the impacts from ice floes and the transducer assembly was severely damaged. All four transducer heads were scoured off at their outer periphery, and in one case the metal cage embedding the transducer face was torn. Moreover, two of the transducer heads were loosened from their proper connection to the transducer electronics housing because the connecting bolts had been lengthened by leverage, leading to gaps of up to 3 mm wide between the transducer heads and the electronics housing. Through these gaps sea water flooded the electronics housing. Because of the severeness of the damages, there was no way of repairing the transducer assembly on board of the ship and to employ the ADCP during the further parts of the cruise. The thermal structure of the upper 700 to 800 meters was measured by 194 XBT-profiles which were recorded with a Nautilus-system. Times and locations of the individual profiles are given in Table 2.3 and 2.4. Comparison between 8 XBT and CTD measurements at the same stations confirmed the accuracy of 0.2 K given by the manufacturer. The data obtained are depicted as vertical sections in Figure 2.14. Sea surface temperature and salinity were recorded continuously in the bow thruster channel at about 5 m depth with a thermosalinograph supplied by Meerestechnik-Electronik (ME). The data were controlled by salinity samples taken at the inlet to the instrument and the temperature measurements of the CTD. The following corrections have to applied to the recorded data: Ttrue=0.921 Trecorded- 0.253 Strue=0.949 Srecorded- 1.772 The corrected data will then be accurate to 0.03 K and 0.03. However, it has to be taken into account that occasionally a water-ice mixture is flowing in sensor head which results in erroneous data. The error is obvious by the reduced conductivity due to the ice. Therefore we do not use the thermosalinograph data along the transect but refer to the CTD-data in 10 m depth (Figure 2.9). The T/S-profiles across Drake Passage and from Antarctica to South Africa are shown in Figure 2.15. Table 2.3: XBT-Section C. San Juan - King George Island St. Date Time Position Depth No. GMT Lat Long m S W (uncorr.) ------------------------------------------------ 1 18.11.90 2357 54°39' 63°31' 122 2 19.11.90 0112 54°54' 63°19' >1800 3 0203 55°07' 63°08' 2639 4 0307 55°20' 62°57' 4171 5 0403 55°34' 02°48' 4141 6 0518 55°48' 62°35' 4090 7 0625 56°01' 62°25' 3953 8 0745 56°15' 62°11' 4040 9 0850 56°29' 62°00' 4100 10 0958 56°42' 61°48' 3000 11 1058 56°56' 61°39' >3000 12 1158 57°09' 61°27' 3819 13 1258 57°23' 61°14' 3845 14 1405 57°38' 61°02' 3631 15 1456 57°50' 60°52' 3601 16 1601 58°04' 60°42' 4305 17 1739 58°28' 60°21' 3073 18 1831 58°31' 60°12' 3600 19 1930 58°44' 60°03' 3715 20 2035 58°58' 59°50' 6428 21 2135 59°11' 59°39' 4090 22 2250 59°25' 59°27' 4298 23 20.11.90 0004 59°40' 59°13' 2142 24 0108 59°52' 59°02' 5930 25 0209 60°06' 58°49' 3490 26 0321 60°20' 58°36' 3868 27 0421 60°33' 58°23' 3912 28 0526 60°47' 58°11' 4266 29 0633 61°00' 57°58' 4910 30 0739 61°14' 57°45' 2499 31 0840 61°27' 57°33' 903 32 0945 61°41' 57°18' 399 33 1042 61°54' 57°10' 259 34 1201 62°06' 57°26' 743 35 1315 62°13' 58°02' 1280 36 1403 62°17' 58°24' 1100 37 1501 62°17' 58°44 464 Table 2.4: XBT-Section Antarctica - South Africa St. Date Time Position Depth No. GMT Lat Long m S W (uncorr.) ------------------------------------------------ 106 20.12.90 0406 68°11' 04°28' 4086 107 1000 67°45' 03°09' 4283 108 1435 67°32' 01°04' >4000 109 1717 67°15' 00°24' 3451 110 1920 67°00' 00°52' >4500 111 2220 66°30' 01°49' 4080 112 21.12.90 0005 66°15' 02°21' 3680 113 0155 66°00' 02°51' 3390 114 0340 65°45' 03°17' 3669 115 0625 65°15' 03°21' 2627 116 0744 65°00' 03°23' 2530 117 0906 64°45' 03°26' 118 1031 64°30' 03°29' 2177 119 1157 64°15' 03°31' 2600 120 1316 64°00' 03°34' 3159 121 1411 63°45' 03°36' 4365 122 1601 63°30' 03°37' 4940 123 1722 63°15' 03°41' 5055 124 1844 63°00' 03°44' 5360 125 2001 62°45' 03°31' 5340 126 2125 62°30' 03°16' 5378 127 2240 62°15' 03°02' 5372 128 2355 62°00' 02°49' 5380 129 22.12.90 0120 61°45' 02°34' 5378 130 0230 61°30' 02°20' 5376 131 0350 61°15' 02°07' 5122 132 0510 61°00' 01°53' 3341 133 0607 60°48' 01°42' 5400 134 0745 60°30' 01°27' 4181 135 0902 60°15' 01°15' 4303 136 1136 59°45' 00°51' 4924 137 1245 59°30' 00°39' >4200 138 1517 59°00' 00°14' 4488 139 1637 58°45' 00°02' 4599 140 1800 58°29' 00°12' 4428 141 1905 58°15' 00°22' 3885 142 2010 58°00' 00°34' 3900 143 2135 57°45' 00°45' 4210 144 2250 57°30' 00°58' 3905 145 23.11.90 0006 57°15' 01°10' 3368 146 0235 56°45' 01°33' 3563 147 0350 56°30' 01°44' 4187 148 0504 56°15' 01°55' 4045 149 0640 55°58' 02°09' 3386 150 0745 55°44' 02°18' 3371 151 0855 55°30' 02°29' 2640 152 1013 55°15' 02°41' 2460 153 1124 55°01' 02°51' 3143 154 1244 54°45' 03°03' 2645 155 1356 54°30' 03°14' 2606 156 1835 54°20' 03°24' 2702 157 1915 54°15' 03°15' 2400 156 2120 54°00' 02°36' 2495 157 2317 53°45' 01°59' 2040 158 24.12.90 0110 53°30' 01°25' 2658 159 0305 53°15' 00°50' 2358 160 0416 53°05' 00°29' 2600 161 0454 53°00' 00°19' 2481 162 0645 52°45' 00°15' 2720 163 0820 52°30' 00°46' 2800 164 1015 52°15' 01°19' 2800 165 1204 52°00' 01°52' 2600 166 1355 51°45' 02°24' 3053 167 1545 51°30' 02°57' 3485 168 1735 51°15' 03°28' 3390 169 1825 51°00' 04°00' 3608 170 1950 50°57' 04°06' 3553 171 2125 50°45' 04°30' 3231 172 2314 50°30' 05°02' 3349 173 25.12.90 0145 50°15' 05°33' 3659 174 1120 50°00' 05°58' 3711 175 1300 49°45' 06°11' 3519 176 1440 49°30' 06°23' 3500 177 1625 49°13' 06°37' 3464 178 1830 49°00' 06°48' 3684 179 2036 48°45' 07°02' 3890 180 2245 48°29' 07°15' 2182 181 26.12.90 0039 48°15' 07°27' 2465 182 0247 47°59' 07°43' 4158 183 0430 47°45' 07°53' 3090 184 0630 47°30' 08°05' 2550 185 0819 47°15' 08°18' 1837 186 1004 47°00' 08°31' 3452 187 1152 46°45' 08°43' 3685 188 1337 46°30' 08°55' 4420 189 1520 46°15' 09°07' 4680 190 1655 46°01' 09°19' 4650 191 1850 45°45' 09°32' 4563 192 2230 45°30' 09°43' 4513 193 2220 45°15' 09°55' 4610 194 27.12.90 0005 45°00' 10°08' 4710 195 0144 44°45' 10°20' 4748 196 0321 44°30' 10°31' 4981 197 0509 44°15' 10°43' 4231 198 0647 44°00' 10°55' 4305 199 0930 43°45' 11°07' 4409 200 1120 43°28' 11°19' 4980 201 1250 43°15' 11°31' 4591 202 1430 43°00' 11°43' 4703 203 1610 42°45' 11°55' 4505 204 1742 42°30' 12°06' 4606 205 1933 42°13' 12°20' 3239 206 2048 42°00' 12°29' 5102 207 2217 41°45' 12°40' 3329 208 2349 41°30' 12°51' 2930 209 28.12.90 0013 41°15' 13°02' 2100 210 0140 41°00' 13°10' 4500 211 0322 40°45' 13°22' 4626 212 0506 40°30' 13°36' 4934 213 0652 40°15' 13°48' 4842 214 0835 40°00' 13°59' 4135 215 1010 39°45' 14°10' 4679 216 1321 39°29' 14°21' 4760 217 1453 39°13' 14°31' 4730 218 1514 39°00' 14°40' 4744 219 1657 38°57' 14°51' 4853 220 1830 38°29' 15°04' 4856 221 2253 37°51' 15°33' 4866 222 2335 37°45' 15°37' 4396 223 29.12.90 0104 37°30' 15°49' 4788 224 0229 37°15' 15°58' 4708 Figure 2.14: XBT sections across Drake Passage (top) and from Antarctica to South Africa (bottom) carried out during ANT IX/2. For location see Figure 2.1. Figure 2.15: T/S-profiles across Drake Passage (top) and from Antarctica to South Africa (bottom) measured with a thermosalinograph during ANT IX/2. For location see Figure 2.1. 3. CHEMISTRY 3.1. Measurements of biogenic sulfur compounds and their reaction products in sea water and the marine atmosphere R. Staubes (IfMG) Objectives Oceanic emissions of biogenic sulfur gases like dimethyl sulfide (DMS), carbonyl sulfide (COS), carbon disulfide (CS2) and methyl mercaptan (CH3SH) constitute a major flux of sulfur to the atmosphere, a source which is believed to be responsible for the background levels of SO2, non-sea salt sulfate and methanesulfonic acid. These compounds are important factors in cloud chemistry and global climate as contributors to cloud condensation nuclei. The dominant sulfur compound released from the oceans and thus the most important precursor of non-sea salt sulfate is considered to be DMS which is produced from metabolic processes in certain algae. Work at sea During ANT IX/2 we performed simultaneous measurements of dimethyl sulfide (DMS), carbonyl sulfide (COS), carbon disulfide (CS2) and methyl mercaptan (MeSH) in sea water and the atmospheric boundary layer. The concentrations of the main reaction products sulfate and methanesulfonate in aerosols in the atmosphere were determined. The air samples were collected at the front of the ship's upper deck; to minimize the influence of the ship two outriggers were fixed at the rail. Aerosols were sampled on filters; the analysis of the ion concentration in the aerosols will be carried out in the laboratory in Frankfurt. The seawater samples were taken from the ship's continuous seawater pumping System. The concentration of atmospheric and dissolved DMS, COS, CS2 and MeSH were analyzed by means of a gas chromatographic system equipped with a flame photometric detector. Biological data of the seawater have been collected during the cruise to aid the Interpretation of the findings. Due to our participation in the cruise legs ARK Vll/2, ANT IX/1 and ANT IX/2 of "Polarstern" the concentration profiles of atmospheric and dissolved DMS, COS, CS2 and MeSH could be examined from 82°N to 71°s. Preliminary results The data show that DMS is the dominant sulfur gas in all sea water samples examined, with smaller amounts of COS, CS2 and MeSH in sum accounting for less than 20% of the observed sulfur in seawater. Atmospheric DMS in the boundary layer was characterized by a significant spatial variability, while COS was distributed fairly homogeneously along the cruise. Traces of biogenic sulfur gases other than DMS and COS were found only in a limited number of atmospheric samples. 3.2. Measurements of the concentration of Nitric acid, Ammonia and Ammonium Nitrate in the marine atmosphere T. Papenbrock (RUB) Objectives Nitric acid (HNO3) is a final, stable product of atmospheric NOx and HOx chemistry. One third of the acid rain is caused by nitric acid. Hence, nitric acid is an important indicator for two of the most important cycles in clean and polluted air. Ammonia (NH3), one of the most important bases in air, is mainly produced by biological processes, It has been found in clean and polluted air, even in the marine atmosphere, for example in the Sargasso Sea. Ammonium nitrate participates in the acid-base equilibrium with gaseous nitric acid and ammonia. This equilibrium depends on temperature and relative humidity of the air masses. For a better understanding of the concentration distribution of these three components and the equilibrium in the atmosphere, it is important to do simultaneous measurements. Work at sea Our method for measuring the concentration of nitric acid and ammonia in air is based on laser photolysis yielding excited OH and NH radicals. The fluorescence intensities of the two species are taken as a measure for the nitric acid and ammonia mixing ratios in the atmosphere. At present the detection limits for long integration times (one hour) is 0.04 ppbv for nitric acid and 0.3 ppbv for ammonia, respectively. Our method allows direct and continuous measurements. To examine the concentration of ammonium nitrate in air we took Denuder probes with sampling times between 40 and 64 hours. The air was sampled at the front of the ship's upper deck and pumped through an 8- meter long Teflon tube to the photolysis cell. The analysis of the samples will be performed in our home laboratory after the cruise. Preliminary results The highest nitric acid and ammonia concentrations were measured in the Strait of Magellan after leaving Punta Arenas. The maximum values were 250 pptv for nitric acid and 600 pptv for ammonia, respectively. During the following days the concentrations slowly decreased with north-westerly winds. Then the wind changed direction and we measured air masses coming from the east. The concentrations decreased very quickly with the values often below the detection limits. Due to our participation in the cruise legs ARK VII/2 and ANT IX/1 and 2 of "Polarstern" in 1990, the concentration profiles of atmospheric gaseous nitric acid and ammonia could be examined from 82°N to 70°s. 3.3. Organobromine compounds in the ocean and atmosphere T. Bluszcz, O. Schrems (AWI) Objectives A considerable amount of the bromine which is present in the atmosphere originates from natural sources. The oceans are important sources for methyl bromide (CH3Br) and bromoform (CHB3). These are compounds which are produced by marine macro-algae. Anthropogenic emissions of organobromine compounds like the halons 1301 (CF3Br) and 1211 (CF2ClBr), however, are responsible for the increase of the bromine concentration in the stratosphere due to their long life times. So far, halons have very low concentrations in the atmosphere, but show an increasing tendency. Increasing production and emission rates of these chemicals can be expected in the future. Therefore, these anthropogenic source gases are a potential reservoir for stratospheric bromine radicals which are efficiently involved in the catalytic ozone depletion cycles. On the other hand a significant ozone depletion potential of the biogenic organobromine compounds has to be considered for the lower stratosphere. The objective of our work is to obtain horizontal concentration profiles of various volatile organobromine compounds during legs 1, 2 and 4 of the "Polarstern"- cruise ANT/IX. The profiles will provide information about the global distribution of these compounds, as well as information about the biogenic and anthropogenic contributions to stratospheric ozone depletion catalyzed by bromine radicals. In order to investigate the air-sea exchange of bromine compounds we collected also surface water samples for later analysis. Work at sea The air samples were taken 20 m above sea level through a short 1/4" Teflon tube. Gas chromatographic analyses of the samples were performed in the air chemistry container at the upper deck of the ship. During sampling the wind direction was carefully checked in order to avoid contamination of the air samples by the ship. The applied sampling method was cryogenic preconcentration of the samples by means of liquid argon as coolant. The air was pumped at a constant flow rate through a U-tube (filled with silylated glass wool) which was kept in a dewar containing liquid argon. In this way the trace gases were frozen out inside the U-tube. Prior to the condensation of the trace gases the air moisture was removed by means of a permeation gas dryer or a cold trap kept at -20°C The samples were transferred from the U-tube to a focusing column and from there injected into the GC. The gas chromatographic separation of the components was achieved with a fused silica capillary column. For the analyses of these halogen-containing samples the GC was equipped with a highly sensitive electron capture detector (ECD). During the leg ANT IX/2 about 120 air samples were directly measured with the gaschromatograph installed in the air chemistry container. For control measurements and application of other analytical methods in the home laboratories an additional air sample was collected daily, sealed and stored at low temperature. Gas chromatography-mass spectrometry (GC-MS) coupling and GC-FTIR coupling will be applied at home for the complete identification of the peaks in the gaschromatogrammes. For the investigation of the air-sea exchange of the bromine species water samples have been taken from the seawater line at about 60 stations and also kept at low temperature. These samples will also be analysed in the home laboratory. Preliminary results At the beginning of the cruise we tested several variations of our air sampling technique. Removal of the air moisture by means of a cold trap (-20°C) prior to the condensation of the trace gases turned out to be the most suitable procedure for preparing the air samples. By comparison with calibrated standards of CH3Br, CHBr3, CF3Br and CF2ClBr we could perform a preliminary quantification of the samples. It was found that these compounds are present in the marine troposphere at concentrations in the low pptv range. A listing of the compounds according increasing concentrations provides the following order: CF3Br < CF2CIBr < CH3Br < CHBr3. The final evaluation and statistical treatment of the gaschromatogrammes will be performed in the home laboratory. 3.4. Biogeochemistry of Silica L. Goeyens (VUB), J. Krest, A. ROSS (OSU), A. Leynaert, B. Quéguiner, O. Ragueneau (IEM), L. Lindner (RUU) Objectives During EPOS Leg 2, high biogenic silica production rates have been measured in the marginal ice zone of the western part of the Weddell Sea and at one station in the Scotia Sea. Comparison with previous studies conducted in the Antarctic Circumpolar Current and in the Ross Sea indicated that the dynamics of silicon in the above mentioned subsystems are quite different. The present study was initiated to bring more information on the importance of the Weddell Sea ecosystem in the silicon budget of the Southern Ocean. Work at sea Eleven stations were sampled in the Weddell Sea (from 63°12'S, 53°41'W to 71°06'S, 11°23'W) at depths ranging from 0 to 300 m. For production experiments, sampling depths were determined with reference to quantameter profiles (respectively 100%, 25%, 10%, 3%, 1% and 0.1% of surface incident light measured as PAR). 24h incubations were conducted in a deckincubator where in situ light was simulated by using different transmission neutral filters. The deck-incubator was cooled by running surface water. Additional depths were sampled to obtain complete profiles of particulate organic carbon, particulate organic nitrogen, biogenic silica, chlorophyll a and nutrients (silicate, nitrate, nitrite, ammonium, phosphate) in the upper 300 m at each station. At each photometric depth the production of biogenic silica was measured by means of stable silicon (30Si) and radioactive silicon (32Si) uptake experiments. For the latter, size-fractionation (on 0.4 and 10 µm filters) was performed at the 25% light level. The radioactive 32Si- silicate enables us to measure phosphorus uptake rates also because it decays into radioactive 32P-phosphate. Dissolution rates of biogenic silica were followed in parallel with production measurements by using the stable 29Si method. The carbon production was measured with the classical 14C method. The nitrogen production was measured only in surface water using the 15N procedure. Phytoplankton samples were collected (lugol fixation) only at depths where production experiments were done and further phytoplankton samples were taken by means of a vertical net in order to estimate the Al/Si content of diatoms. Preliminary results For most of the stations production results must be considered as maximum potential production rates because of the importance of ice cover during the cruise (especially for Sta. B3 to B9). In those conditions natural phytoplankton populations experience a different light regime (with periods of darkness under ice) from the one used during incubations. The distribution of major nutrients indicates weak biological activity during the study period. Surface water silicate, nitrate and phosphate concentrations were respectively about 80 µM Si-Si(OH)4, 30 µM N-NO3, 2 µM P-PO4. As far as ammonium is concerned the measured concentrations were always very low. They almost never amount more then 0.2 µM N-NO4; some stations, near 65°S - 66°S, show, however, a slight increase in ammonium concentration and a corresponding decrease in surface nitrate. But still nitrate concentrations are as high as 27 µM N-NO3 in this area. In general these stations were also characterized by a slightly increased phytoplankton production. Preliminary results of 14C uptake experiments indicate low levels of primary production. Maximum uptake rates in a given depth were encountered in surface waters (range : 0.15-0.54 mmol C.m-3d-1). The lowest rates were observed at the ice-shelf station where the euphotic layer reached down to 138 m. Maximum rates were measured at station B5 (31°47' W, 66°07' S) and ice-edge station B11 (03°57' W, 68°00' S). Depth-integrated production rates (Table 2.5) ranged between 12.2 and 26.2 mmol C m-2d-1 (146-314 mg C m-2d-1). These low values can be related both to the importance of the ice cover and the low temperatures which must prevent the emergence of large phytoplankton developments at this period of the year. First results obtained by the 32Si method indicate low uptake rates both for phosphorus and silicon (Table 2.5), as well as for carbon uptake. Silica production rates range between 0.62-8.02 mmol Si m-2d-1. The highest rate was observed at station B1 and must be taken as characteristic of coastal water rather than the Weddell Sea. At this station the >10 µm fraction accounted for 86.1% of silica uptake rates. The other stations fall within the lower part of the range of production rates that were measured during EPOS Leg 2. The same trend is observed for phosphorus for which the uptake rates range between 0.08-0.61 mmol P m-2d-1. At station B7 the 32Si/32P uptake experiment was conducted on brine (incubated under daylight conditions) and indicated uptake rates one order of magnitude higher than in the water column. Preliminary assimilation ratios, calculated from depth-integrated production rates, are given in Table 2.6. With the exception of station B4, C/P ratios range between 101.5-168.8, close to the Redfield ratio (C/P = 106). Sta. B1 to B3 exhibit the highest Si/P ratios which suggest the dominance of diatoms in phytoplankton populations. This is also indicated by the high Si/C ratios measured at Sta. B2 and B3. Sta. B5 and B6 are quite different with regards to the three ratios and exhibit low silicon uptake as compared to carbon and phosphorus which can be related to different phytoplankton populations (dominance of non-siliceous phytoplankton). Sta. B4 is different from the other stations, showing high phosphorus uptake relative to carbon and silicon but the high Si/C ratio which suggests the dominance of diatoms in phytoplankton as for the first stations. Table 2.5: Depth-integrated carbon, silicon and phosphorus production rates (in mmol C m-2d-1, mmol Si m-2d-1, mmol P m-2d-1, respectively) N° Sta. C prod. Si prod.* P prod.(data from 32Si method) ------- ------ --------- ------------------------------ B1 - 8.02 - B2 13.9 1.64 0.14 B3 13.0 1.11 0.08 B4 17.9 2.35 0.38 B5 22.0 1.17 0.19 B6 18.1 0.62 0.11 B7 13.1 - - B8 22.5 0.33 B9 26.2 0.33 B10 19.8 0.38 B11 12.2 Table 2.6: C/Si/P assimilation ratios calculated from depth-integrated production rates No Sta. Si/C Si/P C/P ------ ---- ---- ----- B1 - 13.0 - B2 0.12 12.0 101.5 B3 0.09 14.4 168.8 B4 0.13 6.1 46.5 B5 0.05 6.1 115.8 B6 0.03 5.4 157.4 3.5. Biogeochemistry of Barium L. Goeyens (VUB) Objectives Particulate Ba, as well as other elements like Ca, Sr and Si, trace former biological activity in the marine environment. More than for particulate carbon or nitrogen, the longer turnover time of particulate barium is of interest for its tracer properties. Whether Ba is taken up by organisms in an active or passive way is still a matter of debate. On the one hand active uptake was described in the literature, but on the other hand it was stressed that Ba precipitates in small microenvironments of cell and detritus aggregates as barite crystals. In any case barite crystals represent the major part of particulate Ba in the total suspended matter. During the remineralization process the organic matrix (of cells and/or aggregates) decays and sets the barite crystals free in the sea water, where sedimentation and slow dissolution take place. The presence and distribution of particulate Ba in the marine environment is, however, very dependent on assimilation and break down processes. In general a vertical Ba profile shows peak concentrations in the surface water and very often secondary peaks near the oxygen minimum. For this reason the study of the biogeochemical cycle of Ba is of interest for other parameters such as nutrients, oxygen, particulate carbon and nitrogen, chlorophyll a, and species distributions, but also for flux studies such as nutrient assimilation and regeneration. Work at sea The filtration of total suspended matter for particulate Ba, Ca, Sr, AI and Si analysis demands large amounts of sea water. Normally 10 liters are filtered; on previous cruises even more than 20 l were filtered. The total suspended matter (TSM) is collected on membrane filters, Millipore cellulose acetate filters or Nuclepore polycarbonate filters. They are simply dried at 60°C on board and stored in Petri dishes until analysis in the home lab. During the ANT IX/2 cruise samples for TSM were taken at 9 stations. At every station the samples were selected according to the plankton distribution study, carried out by Baumann and Brandini. In general sampling covered the upper 500 to 600 m. The analyses will be carried out in the home lab by dissolution of the samples (filters) after LiBO2 fusion and determination of the Ba (Ca, Sr, AI and Si) concentrations by ICP. 4. MARINE BIOLOGY 4.1. Energy flux at the base of the Antarctic food web M. Baumann, F. Brandini, F. Kurbjeweit (AWI), L. Goeyens (VUB), J. Krest, A. ROSS (OSU), B. Quéguiner (IEM) Objectives The information concerning the Antarctic food web is mostly based on descriptive work such as spatiotemporal distributions of nutrients, primary production, phytoplankton biomass (chlorophyll), and zooplankton. To our knowledge, the energy flux from the primary producers to the primary consumers within the pelagic ecosystem is estimated only by means of such a descriptive approach. As an attempt to gain a more precise picture of the trophic relationships among the planktonic communities in Antarctic regions, we focused on the quantitative nitrogen transfer at the first and second trophic level using the stable isotope 15N as a tracer. This study was carried out in terms of unialgal culture experiments using the common Antarctic copepod Metridia gerlachei as a primary consumer and six 15N-labelled algal species as primary producers. Work at sea Five diatoms (Thalassiosira spp., Nitzschia curta, Porosira glacialis, Rhizoso- lenia alata, Chaetoceros socialis) and a prymnesiophyte (Phaeocystis spp.) were isolated from the plankton in the Weddell Sea. The species were grown in natural sea water without the addition of nutrients etc., except EDTA as a chelator. To one liter of 0.2 µm filtered sea water, 3.72 mg of EDTA were added. The stock cultures were stored at 1°C and 30 µE m-2d-1 continuous light. The copepod Metridia gerlachei was caught by means of a bongo net with mesh width of 100 µm. The animals were transferred by pipette into filtered seawater and allowed to starve for 48 hours before starting the experiments. The experiments were carried out in 5-1 Duran flasks at 1°C and 30 µE m-2d-1 continuous light. Every 24 hours the unialgal cultures were spiked with about four micromoles of 15NH4+ (97% 15N). It was assumed that after three days the algae were labeled through out. A mixture of 500-ml aliquots of each experimental vessel served as a seventh culture. For the grazing experiment, 20 female copepods were added to each bottle. Sampling was performed according to Table 2.7. Table 2.7: Sampling scheme during the phytoplankton grazing experiment Parameter 0h 24h 48h 72h* 96h 120h ------------------ -- --- --- ---- --- ---- POC/PON, NH4+ x x x nutrients x x x x x x cell number x x x x x x Chl a x x 15N in PON x x 15N in NH4+ x x 14C - Assimilation x x 15NH4+ - Addition x x x x * Addition of 20 animals to each culture. Due to the fact that most of the analyses will be done in the home labs, no results can be given here. However, we hope that the experiments will provide information on the ammonia uptake of 6 of the common Antarctic phytoplankton species and on the extent Metridia gerlachei feeds on these species. 4.2. Phytoplankton biomass and species distribution M. Baumann, F. Brandini (AWI) Objectives In marine environments, the availability of light and nutrients are important preconditions for the onset of phytoplankton development. The melting of ice along the marginal ice zones of the Weddell Sea during the spring/summer period increases both the mean light penetration and the vertical stability of the water column. Therefore, phytoplankton cells are maintained within the euphotic layer for longer periods, increasing the primary production along the receding ice edge. Moreover due to intense upwelling of the Warm Deep Water, the Weddell Sea is considered as one of the nutrient-richest waters of the World Ocean and there seems to be no evidence that the macro- nutrient concentrations may ever limit phytoplankton growth. During ANT IX/2 our objective was to examine the distributions of phytoplankton, chlorophyll, and particulate organic carbon and nitrogen (PON and POC) on a large-scale northeast-southwest transect across the Weddell Sea with special regard to the marginal ice zone. Due to the almost complete ice Cover in the area of the transect we could not perform more stations within the ice edge in order to resolve precisely the spatial gradients of biological Parameters usually observed in these areas. Most of our stations were located in heavily ice covered areas (8/10 to 10/10) with very low biological activity in the water column compared to the ice edge zones and to the ice associated communities. Work at sea A total of 21 stations were vertically sampled (10 depths) by means of a rosette sampler with an integrated CTD system, to determine phytoplankton biomass in terms of chlorophyll, cell counts, and PON/POC measurements. For the microscopical analyses of species composition, samples were obtained by vertical net hauls, with a mesh size of 20 µm. The microscopic analy- ses of unpreserved net samples were performed immediately after sampling. Light attenuation was estimated at each station with the Secchi-disk, not in order to determine the euphotic zone, but to get an idea about cell abundance. Preliminary results At three stations (39, 43 and 101) no meaningful estimate of the Secchi depth could be determined due to darkness and/or rough sea. The lowest value (17 m) was obtained on the western shelf at station 40, indicating a more developed state of the phytoplankton community, and the highest (55 m) was found on the shelf off the Antarctic Peninsula (Figure 2.16). Net samples were very poor during the whole transect and usually dominated by diatoms. At the first stations of the northeastern Part (e.g. Sta. 40, 45), species were dominated by Corethron criophilum, Thalassiosira, Odontella, Nitzschia, Porosira glacialis, Rhizosolenia, Chaetoceros, and Coscinodiscus. In the deep waters of the gyre, Nitzschia spp, Rhizosolenia alata, Chaetoceros socialis and dinoflagellates, such as Gyrodinium and Gymnodinium, were most frequent, whereas in the southeastern sector mainly Coscinodiscus, Chaetoceros and Rhizosolenia appeared. Figure 2.16: Secchi depths measured during ANT IX/2. The nano-size cells were observed in the middle of the gyre (Sta. 66 and 75) after filtration of 500 ml of seawater from the euphotic zone on membrane filters (Sartorius Inc., 0.8 µm). The material was transferred to microscopic slides and observed under x1000 magnification. It turned out that mainly phytoflagellates of different groups (dinoflagellates, cryptophycean, prasinophycean) but also zooflagellates (choanoflagellates) dominated the samples. Within the smaller size category (< 10 µm) the diatoms were dominated by Nitzschia cylindrus. Ice algae samples were obtained at three different stations located in deep, near -slope, and the shelf areas along the cruise track. Ice algal communities over deep water were totally dominated by Phaeocystis spec. - no other algae could be found. The near-slope sample contained both Phaeocystis and diatoms, mainly Nitzschia longissima, N. curta, and other pennate species; the shelf sample was dominated by diatoms, the most characteristic species being N. stellata, N. curta, N. closterium, Odontella weissflogii, Amphiprora spec.. Phaeocystis could not be found in this sample. It might be suggested that species composition in the ice algae assemblages are related to depth of the water column, but this should be confirmed in further investigations. 4.3. DMS - Production by Antarctic phytoplankton species M. Baumann, F. Brandini (AWI), R. Staubes (IfMG) Objectives It is well established that the oceans are a significant source of organic sulfur compounds, which are largely biogenic. The most important one is probably dimethyl sulfide (DMS), which is also produced by marine phytoplankton. It is suggested that DMS production is due mainly to dinophyceae and prymnesiophyceae. However, the importance of diatoms in this connection is still unclear and especially in polar regions has this aspect not been investigated. During ANT IX/2 the DMS production of eight dominant Antarctic phytoplankton species under several light- and temperature conditions was tested. Figure 2.17: Production of DMS by 7 Antarctic diatom species at 1°C and 6 different light conditions in 36 h. Because the initial value was subtracted, negative values occur in those samples where DMS was not produced. Work at sea Seven diatom species (two Thalassiosira spp., Nitzschia curta, Porosira glacialis, Rhizosolenia alata, Rhizosoleni spp, Chaetoceros socialis) and a prymnesiophyte (Phaeocystis spp.) were isolated from the plankton of the Weddell Sea. The species were grown in natural seawater without the addition of nutrients etc., except EDTA as a chelator. 3.72 mg of EDTA were added. to one liter of sea water filtered with 0.2 µm. The stock cultures were stored at 1°C and 30 µEm- 2s-1 continuous light. For the experiments, a 2 I culture medium with cells was shaken vigorously and distributed in 100 ml flasks. One aliquot was kept for a quantitative cell analysis and another for the determination of the initial DMS content. The experiments were carried out in an incubator which allowed the choice of six light conditions (350, 160, 100, 50, 18, and 3.5 µEm-2s-1) and two temperatures (1°C and -1.6°C). The DMS released by the algae after three days was analyzed according to the method described in 1.3.1. Figure 2.18: Production of DMS by Phaeocystis spp. at 1°C and six different light conditions. Preliminary results Figure 2.17 shows the preliminary results of DMS produced by the diatoms at 1°C Although the values still have to be related to cell numbers, one can see that except Thalassiosira- and the Rhizosoleni spp., all diatoms produced DMS; Rhizosoleni alata obviously released the greatest amount. Compared to diatoms, the prymnesiophyte Phaeocystis sp. produces significantly more DMS (Figure 2.18). While values for the diatoms range from 0.1 to 1.5 ng DMS/ 10 ml, the Phaeocystis culture produced up to 20 ng DMS/10 ml. Later we intend to express the results as DMS production per cell surface for better comparisons of production rates among species. 4.4. Effect of dissolved organic compounds derived from "brown ice" On the development of surface phytoplankton in the Weddell Sea M. Baumann, F. Brandini, (AWI); J. Krest, A. ROSS (OSU) Objectives The blooming of phytoplankton cells in the ice edge zones of the Antarctic Ocean has been associated with a vertical stabilization of the surface water layers during ice melting. More recently, the seeding hypothesis has been claimed to be crucial for increasing phytoplankton biomass in the near surface layers, as algae from the brown ice are released in great quantities during the receding of the ice in early spring. However, it should be mentioned that the water column not only receives particulate material from the ice but also dissolved organic compounds making the seeding process much more complex than it is assumed. According to recent studies on spatial distribution of phytoplankton in the ice edge zones, the dynamics of the blooming should be analyzed at two consecutive stages, starting with the ice associated species (Nitzschia spp., Navicula spp., Amphiprora spp., and Fragillaria spp.) immediately after the melting of the ice. Due to grazing pressure and the rapid sinking of cells - ice algae are strongly silicified and therefore heavier than planktonic species - the phytoplankton composition in the ice edge shifts from an ice algae characterized community to a more holoplanktonic community (Thalassiosira spp., Rhizosoleni spp., Chaetoceros spp., and Corethron criophilum). We believe that the development of this second stage is strongly related to the input of great amounts of dissolved organic compounds, derived from the "brown ice" community, into the surface water. The dissolved organic material possibly acts as chelators for essential trace metals (Fe, Mn, etc.), improving the development of planktonic diatoms. Although the stimulating effect of the melted "brown ice" on the phytoplankton development was previously mentioned, it seems that hitherto no proper attention has been paid to this. Therefore, during ANT IX/2 we decided to test the potential stimulating effect of dissolved organic material from "brown ice" on the development of the natural phytoplankton of the Weddell Sea. Work at sea For testing the effect of DOM from melted ice samples on the potential growth of natural phytoplankton populations, two different "brown ice" (BI 1, BI 2) samples were taken. The analysis of species composition and the contents of the macro-nutrients revealed that they differed both in microalgal community structure and nutrient contents. BI 1 was totally dominated by Phaeocystis colonies and BI 2 by a mixture of Phaeocystis and diatoms. The growth potential of natural phytoplankton from surface seawater was experimentally tested as follows: 1: 800 ml SSW1) + 200 ml FSW2) 2: 800 ml SSW + 200 ml FSW + EDTA 3: 800 ml SSW + 200 ml melted BI 1 4: 800 ml SSW + 200 ml melted BI 2 1) surface seawater 2) filtered seawater All experiments were done in duplicates (A, B). 200 ml of SSW were added to the control (1 A/B) and EDTA flasks to avoid dilution effects of initial cell concentrations. The experimental flasks were kept at 1°C and 30 µEm-2s-1. Sampling for cell counts and nutrient concentrations (nitrate, phosphate and silicate) was performed every two days for two weeks. Cell numbers were estimated on board after filtration of 50 ml culture medium on cellulose acetate filters (pore size 0,8 µm). If performed very gently, the cells are not destroyed by this procedure and can be counted with a standard microscope directly on the filters. Total nano-size and macro-size diatoms were counted in the same unit area of the filters and hence results are expressed on a relative basis. Nutrient analyses were carried out on board with the aid of an autoanalyzer. Preliminary results Initial cell concentrations in all experimental flasks averaged 200 relative units, and were dominated by Nitzschia curta, N. cylindrus, N. kerguelensis, Chaetoceros dichaeta, Chaetoceros spp., Pseudonitzschia spp., Corethron criophilum, unidentified centric and pennate diatoms. Total diatoms and two different size classes of Nitzschia spp. were considered to represent biomass development. The nano-size Nitzschia cylindrus numerically dominated all the experimental approaches. Figure 2.19 shows clearly the stimulating effect of DOM, derived from both melted BI 1 and BI 2 on growth rates in comparison with the control and EDTA-added flasks. From the differences between cell concentrations after 12 days it might be assumed that DOM derived from diatom - dominated "brown ice" (4 A,B) had a stronger effect on cell doubling rates than DOM from Phaeocystis - dominated "brown ice". In contrast to that no significant differences can be observed when the control and the EDTA added bottles are compared. Initial nutrient concentrations (Figure 2.20) may not be considered limiting for phytoplankton growth as phosphate, silicate, and total inorganic nitrogen averaged respectively 2.0, 66.9, and 27.8 µmol l-1. Ammonium was significantly higher in the DOMIB II- flasks (4 A,B), but decreased to comparatively low concentrations in all experiments after 48 hours. From these preliminary results it may be concluded that DOM released from the "brown ice" of the Weddell Sea certainly has a stimulating effect on cell growth that hitherto has been neglected. We believe that these results represent baselines for future experimental approaches to provide a more detailed picture of the seeding mechanism and its impact on the blooming of the phytoplankton along the receding ice edge zones of polar seas. Figure 2.19: Cell increase during the DOM - experiment Figure 2.20: Changes in nutrient concentrations during the DOM - experiment 4.5. Reproduction and life cycles of dominant copepods in the Weddell Sea F. Kurbjeweit (AWI) Objectives Besides krill (i.e. Euphausia superba) and salps, copepods play the most important role as secondary producers in the pelagic System of the Antarctic and the Weddell Sea. Several Papers have dealt with the distribution and abundance of calanoid copepods in the Antarctic in general, but our knowledge about their distribution, abundance, reproduction and their life cycles are sparse concerning the Weddell Sea. The first aim of this investigation is to examine the distribution and abundance of dominant calanoid copepods such as Metridia gerlachei, Microcalanus pygmaeus, Stephos longipes, Calanus propinquus and Calanoides acutus in space and time in the Weddell Sea during spring and summer. Due to the short period of primary production in this area, it is of major interest to investigate their reproduction Pattern and to obtain if their reproduction is food limited quantitatively as well as qualitatively. With additional biochemical Parameters and Information about the hydrography it might be possible to develop schemes for their life cycles and their role as secondary producers in the pelagic System. Work at sea During ANT IX/2 on the transect from the Antarctic Peninsula to Atka Bay the distribution and abundance of dominant copepods in the upper 1000m of the water column was examined on 13 stations by means of a multinet (100 µm mesh size, 0.25m2 opening area). Samples from five depth Strata at each station were preserved in 4% buffered formaldehyde for future investigation of Stage distribution of the above mentioned copepod species and the examination of gonadal development of their females. For the second part of the investigation a bongo net (10Opm mesh size; 60cm diameter) was lowered on 10 stations to 300m for getting undamaged females for reproduction experiments. Females from the most abundant copepod species were incubated on four stations under in situ conditions in surface water. In addition females of C. acutus, M. gerlachei and S. longipes were starved in 0.2 pm Nucleopore filtered seawater for up to two weeks. Later On, enhancement of reproduction was attempted with high concentrations of mixed algae, mainly diatoms and the prymnesiophyte Phaeocystis sp.. On two stations respiration of female copepods of S. longipes, C. acutus, C. propinquus and M. gerlachei were measured to evaluate their metabolic demands. As additional parameters for the Interpretation of the reproductive potential of the animals under investigation, samples were taken for dry weight, CIN-content, digestive enzymes (trypsin and amylase) and lipids, which will be examined in the laboratory at home. Preliminary results The small copepod species S. longipes was found on merely three stations in high numbers, namely on the first station (station 40) on the shelf of the Antarctic Peninsula and on the last two stations close to the ice shelf in the southeast (Sta. 108, 11 5). M. pygmaeus, the other small calanoid copepod of about one millimeter in length, was found only on two stations in low numbers (63 and 94), while C. acutus and M. gerlachei were abundant on almost all stations. C. propinquus was dominant only on stations in the central part of the Weddell Gyre. Besides these copepods on almost all stations cyclopoid copepods of the genera Oncaea spp. and Oithona spp. were predominant in the micro- and smaller meso-zooplankton size classes. However, radiolarians were also important on all stations, partly clogging nets and acting as a trap for most of the other zooplankton organisms. On station 115 in an inlet at the ice shelf juveniles of Pleuragramma antarcticum (pers. comm. Kellermann) dominated the haul. In situ egg production experiments on five stations (63, 87, 94, 108, 115) carried out for over 24hrs in ambient surface water showed that C. acutus, C. propinquus and M. gerlachei produced well in the southeastern Weddell Sea close to the ice shelf (Sta. 108 and 115), whereas the reproduction of these species decreased with increasing distance from it (Figure 1.22). Except on station 63, where none of the four incubated copepod species reproduced (M. Iongipes was used only here) C. propinquus laid the most eggs followed by C. acutus and M. gerlachei (Figure 2.21). The maximum egg production per day of C. propinquus was 15.8, of C. acutus 10.1 and for M. gerlachei 7.6, respectively. Whether a correlation with chlorophyll concentrations in the water column exists, still has to be proved. Figure 2.21: Intubation of the four dominant copepods Calanus propinquus, Calanoides acutus, Metridia gerlachei and Microcalanus pygmaeus (only on Sta. 63) on a transect from the central part (Sta. 63) of the Weddell Sea to Atka Bay in the southeast (Sta. 115). Egg production experiments with S. longipes (station 40) under starvation in egg separation chambers showed no significant egg production within 7 days. After the addition of mixed algae, mainly diatoms a) without and b) with Phaeocystis sp., the mortality rate was higher in the latter one, but in both incubation series no eggs were laid. In contrast, S. longipes was able to produce 2.8 eggs per day (sd = ±2.0) in tissue culture vessels of only about 3ml volume for three days with Chaetoceros socialis as food source. Its maximum clutch size was 8. Furthermore, Microcalanus pygmaeus produced an average of 7.5 eggs per day (sd = ±3.0) even without food supply to the culture vessels for four days. After that time the mortality rate increased dramatically and no eggs were produced anymore. Its maximum clutch size was 11. On two stations, 45 and 48, 16 females of C. acutus were incubated in 0.2 µm Nucleopore filtered seawater to see for how long they could sustain egg production from preconsumed energy reserves. Although variability in egg production was high on both stations, the cumulative egg production for all females combined for each station leveled off after 10 to 11 days (Figure 2.22). The maximum number of eggs produced on station 45 and 48 was 1355 and 955, or 253 and 195 as maximum numbers for a single female, respectively. Figure 2.22: Cumulative egg production of pooled females of Calanoides acutus On Sta. 45 (open squares) and 48 (filled squares). The respiration measurements showed that small calanoid copepods such as S. longipes respired between 0.065 and 0.081 µI O2 per animal per hour, while large animals as C. acutus respired between 0.244 and 0.456 µI O2 per animal and hour. Respiration of C. propinquus and M. gerlachei ranged somewhere in between. Eggs from all five copepod species under investigation, incubated in filtered seawater at 0°C under dim light conditions (5µEm-2s-1) showed quite different developments. While eggs of C. acutus needed 8 to 10 days to reach 50% of the NI population, those of M. gerlachei needed 3 to 4, and M. pygmaeus only 1 to 2 days. Eggs of C. propinquus from several hatches did not develop at all. 4.6. Comparative studies on the temperature dependence and kinetics of digestive enzymes in crustaceans B. Dittrich (AWI) Objectives As mediators between food uptake and metabolic turn-over, enzymes play a decisive role in ensuring long-term survival of a species as well as of an individual. As highly sensitive proteins their functioning depends not only on nutritional factors but also directly on environmental conditions. Although a variety of investigations has been devoted to nutritional adaptations in zooplankton organisms, few studies have been carried out on thermal acclimation of their digestive enzymes. Most of the proteases known today show an optimum of activity at about 40-50°C Generally, increasing as well as decreasing temperatures result in a decrease of activity which is - in temperate and tropical species - about zero when approaching the freezing point of water and when exceeding 60°C The main interest of the present study is focused on the question of how polar species cope with these extreme unfavorable conditions that exert a lethal effect on all other, not cold-adapted species. The postulation that the nutritional adaptability is a function of the metabolic needs is obviously valid also for thermal adaptability. Work at sea Crustaceans from different systematic groups - decapods, isopods and amphipods - as well as pantopods were obtained by means of an Agassiz- trawl, towed at a depth of 140 - 270 m near King George Island (62°35'S, 55°25'W and 62°54'S, 54°24'W) and near Kapp Norvegia (71°05'S 11°32'W) After collecting and sorting the animals, a large portion was dissected immediately; their midgut glands and gastric fluids were deep-frozen at -80°C and will remain stored at this temperature until further analyses on temperature dependence and kinetics will be carried out at the AWI. After arrival at Cape Town, some of the samples were transported on dry-ice to Germany while the others remained on board "Polarstern". Several individuals of isopods, collected from the Agassiz-trawl off King George Island, were kept individually without any food supply in a temperature-controlled container at 0°C; a small number of them was prepared after each week to obtain information on the resistance to starvation and the influence of such unfavorable nutritional conditions On the enzymatic equipment and activity. Preliminary Results Analysis on midgut glands and digestive fluids in the stomachs of crustaceans collected in the course of EPOS 3 in Austral summer 1988/89, were supplemented by samples from the Skagerrak, the German Bight and the coast of Kenya. The results indicate - at least in the trypsin-like Protease - characteristic differences in the temperature dependence and kinetics, which become obvious especially in the low- temperature range. Temperature optima of the investigated enzymes do not differ significantly from each other and were found at about 40- 50°C. However, the most striking mechanisms of adaptation to permanent low temperatures in the predominantly cold-stenothermic Antarctic species were found to be (1) the high activity even at temperatures near freezing-point which may amount up to 15% of the maximum activity at the temperature optimum and (2) the reduction of activation energy which was found to be only a third of that in temperate and tropical species. Distinct species-specific changes in the enzyme activity after application of selected effectors suggest decisive alterations in the molecular structure of the enzyme protein. However, further detailed analyses on Antarctic species will prove if the results characterize a general phenomenon. 4.7. 32Si applied to marine biology M. Baumann, B. Dittrich, F. Kurbjeweit (AWI), L. Lindner (RUU) Objectives During EPOS leg 2, pilot experiments had already been carried out to underscore the potential of radioactive 32Si. This is a follow-up on the previous studies. 32Si is a weak beta emitter (t1/2=174 y) and is the parent of radioactive 32P (t1/2=14 d). Work at sea Part of the 32Si waste (32Si-silicate in radioactive equilibrium with daughter 32P-phosphate contained in filtered sea water) produced in the course of the 32Si uptake experiments (c.f. section 3.4 ) was used for labeling of a mixed culture of sea algae. This 32Si-32P-labelled culture was subsequently used for grazing studies with an amphipod, an isopod and a copepod, respectively. Preliminary results After 11 days of incubation, the first culture had taken up about one third of the available 32P; the uptake of 32Si was considerably less. A second culture (the first one with additional, nutrient rich, waste water) had after several days of incubation two thirds of the 32P incorporated (and seemingly also more 32Si than in case of the first culture). The results show again that with an adequate selection of the type of culture (preferably of diatoms only) 32Si can be recovered from its waste solutions (however, with a lower specific activity). The previous EPOS experiments with krill had shown them to be a nearly ideal specimen for 32Si studies. Unfortunately, due to the lack of krill during this cruise three other animals were tested. Instead we used an amphipod, an isopod and a copepod. Contrary to all expectations, both starved benthic animals were happily feeding on (labeled) phytoplankton. Dissection of the animals after several days of grazing was followed by radioactive counting of the different tissues. The activities measured in the digestive systems were low, in contrast to that in the exoskeleton and the muscles combined. Only the amphipod produced several greenish slimy faecal pellets with considerable activity, much of it 32P but also 32Si. The copepod (Calanoides acufus, 8 mm) was measured alive at regular intervals during the grazing/fasting cycles, counting the Cerenkov radiation of 32P taken in. This made it possible to estimate the uptake of phytoplankton (on the order of 1% of the available biomass during a period of a week). No faecal pellets were observed to be produced. The earlier hypothesis, given in the above mentioned krill studies, that the mechanical and physiological digestive processes of diatoms being grazed form a first and possibly important step in the remineralization of silicon, seems to find additional support in the present observations. 5. MARINE GEOLOGY 5.1. Bathymetry U. Goldkamp, J. Monk, S. Vucelic (AWI) Objectives During "Polarstern"-cruise ANT V/4 in 1987 a channel-like structure was discovered at 65°40'S, 38°45'W by means of Seabeam fansweep system. The course of the channel was expected to run from SW to NE; accordingly, a rectangular pattern of measurements was planned to investigate the extent and the shape of the channel over a larger distance. From these data the origin of and significance to northeastward bottom water transport will be derived. In addition to this area of special interest, the cruise track was used to continue charting the Weddell Sea. Work at sea Starting November 19th the Hydrosweep system was put in operation and worked for more than 9000 profile-kilometers. Due to technical problems, no hydrosweep data were recorded from 29 November, 12.00 until 30 November, 21.30. After leaving the Georg-von-Neumayer-Station measurements were continued while passing Maud Rise and heading for Cape Town until the end of the leg. After reaching the known position of the channel at 65°40'S and 38°45'W and passing the first turning points of the survey pattern, the track had to be modified, because the ice conditions made it impossible to follow a prescribed course. Nevertheless, the width of the channel was recorded in its whole extent along the channel axis from east to west which was possible because frequently leads were aligned along the channel axis. At the eastern part of the survey, large ice floes prohibited following the course of the channel. The hydrosweep screen on the bridge allowed changes in the course to be made in a way, that the survey of this part of the channel was achieved despite the ice cover. The channel was surveyed over a total length of 144 kilometers with a track line of 500 kilometers. Figure 2.23: Ships track (heavy line) and axis of the deep sea channel in the northwestern Weddell Sea M219 indicates the location of a current meter mooring and PS stand for minicorer samples. On the shelf and the continental slope off Kapp Norvegia, several hydrosweep profiles could be run in spite of unfavorable ice- conditions to supplement data in the area east of the Wegener Canyon. The route to Atka Bight was used to run a profile parallel to former courses. For the passage to Cape Town a course crossing over the eastern slope of Maud Rise from south to north was chosen. The online constructed isoline-plot showed small cone-like structures in this area, even above Maud Rise. During the complete leg, GPS satellites could be used for positioning. Offsets, positioning errors and failing data were recorded, which were due to changes in position of the satellite, inter-satellite constellation and the time free of GPS. Offsets and positioning errors were corrected within one day. Therefore, post processing resulted in an exact positioning of the fansweep profiles and isobaths crossings of Hydrosweep profiles. 5.2. Sediment distribution M. Weber (AWI) Objectives The program can be subdivided in three parts: - a Parasound survey, carried out jointly with the bathymetric group, from Bellingshausen to the Agulhas Basin. - the investigation of the structure, origin and significance of a deep sea channel at 65°40'S, 38°45'W in the northwestern Weddell Sea with Hydrosweep and Parasound. - the development of a minicorer based on the principle of a multicorer, which is fixed under the CTD with a 20 m stainless steel wire, to obtain a large number of geological samples in combination with the oceanographic station with no need of additional ship time. Figure 2.24: Minicorer sampling stations during ANT IX/2. Circles stand for geological and triangles for geochemical sampling Work at sea Parasound and Hydrosweep surveys were carried out in cooperation with the bathymetry group. In addition to the acoustic measurements, two sediment samples were taken using the minicorer and also the current meter mooring 219 was deployed in the center of the channel to get information about the flow velocity (Figure 2.23). This minicorer enabled us to take 37 samples from the sediment surface (Figure 2.24, Table 2.8), mostly on the transect between Bellingshausen and Kapp Norvegia. The use of the minicorer combined with the CTD saved more than four days of ship time normally needed for extra geological stations. Preliminary results Over the length of 144 km (Figure 2.23) the structure occurs at a water depth of about 4650 m. The channel depth relative to its surroundings increases from 60 m up to 100 m. Most of he channel has an asymmetric geometry with a steep and a smooth slope. In the middle and eastern part of the studied area it is a rather small meandering feature (1 to 3 km wide). In the western part, the channel axis straightens and the channel widens to more than 10 km. The quality of the surface samples from the minicorer is the same as from the multicorer. Further investigations including sedimentological, palaeontological and geochemical analysis will be done in the AWI. Table 2.8: Geological sampling during ANT IX/2 Station AWIGELO Date Time geogr. geogr. Water MIC MIC MIC Nb. Nb. Latitude Longitude depth Penetra- Length stored Cruise 18/ (m) tion (m) (m) (m) ---------- --------- -------- ----- ----------- ----------- ---- -------- ------ ------ 042 PS 1952-1 22.11.90 13:40 63°29,92' S 52°08,02' W 924 0,02 0,00 0,00 044 PS 1953-1 23.11.90 09:33 63°44,59' S 50°55,36' W 2413 0,20 0,20 0,04 048 PS 1954-1 24.11.90 23:30 64°24,37' S 45°48,21' W 4434 0,28 0,25 0,04 050 PS 1955-1 25.11.90 22:39 64°49,21' S 42°30,22' W 4684 0,26 0,25 0,25 053 PS 1956-1 27.11.90 15:07 65°54,32' S 40°15,47' W 4607 0,10 0,01 0,01 055 PS 1957-1 28.11.90 09:48 65°40,29' S 37°44,63' W 4727 0,12 0,12 0,04 056 PS 1958-1 28.11.90 20:48 65°11,99' S 39°22,31' W 4757 0,32 0,31 0,04 057 PS 1959-1 29.11.90 06:38 65°24,71' S 37°54,80' W 4736 0,28 0,25 0,25 058 PS 1960-1 29.11.90 19:52 65°38,27' S 36°28,42' W 4770 0,24 0,24 0,04 059 PS 1961-1 30.11.90 02:41 65°43,18' S 35°26,86' W 4777 0,25 0,24 0,04 061 PS 1962-1 30.11.90 22:34 65°59,51' S 33°24,71' W 4760 0,26 0,25 0,25 063 PS 1963-1 01.12.90 17:40 66°07,27' S 31°47.09' W 4786 0,25 0,24 0,04 065 PS 1964-1 02.12.90 06:26 66°16,60' S 30°17,80' W 4800 0,25 0,25 0,04 067 PS 1965-1 02.12.90 19:46 66°27,98' S 28°45,30' W 4850 0,25 0,25 0,04 069 PS 1966-1 03.12.90 06:15 66°37,58' S 27°07,48' W 4860 0,25 0,25 0,25 075 PS 1967-1 05.12.90 10:10 65°57,41' S 30°04,25' W 4847 0,21 0,20 0,04 079 PS 1968-1 06.12.90 09:31 67°28,70' S 31°06,61' W 4625 0,29 0,25 0,25 080 PS 1969-1 06.12.90 15:39 67°18,95' S 29°57,50' W 4682 0,25 0,24 0,04 081 PS 1970-1 06.12.90 22:10 67°08,54' S 28°47,76' W 4815 0,25 0,22 0,04 082 PS 1971-1 07.12.90 04:46 66°57,20' S 27°36,63' W 4819 0,24 0,23 0,04 083 PS 1972-1 07.12.90 11:19 66°45,47' S 26°24,15' W 4854 0,18 0,14 0,04 084 PS 1973-1 07.12.90 17:18 66°53,47' S 25°32,89' W 4841 0,25 0,25 0,04 086 PS 1974-1 08.12.90 06:59 67°13,33' S 24°08,78' W 4857 0,12 0,11 0,04 088 PS 1975-1 08.12.90 21:04 67°30,49' S 22°31,29' W 4893 0,27 0,26 0,04 090 PS 1976-1 09.12.90 09:41 67°50,47' S 20°50,65' W 4919 0,27 0,25 0,25 092 PS 1977-1 09.12.90 00:40 68°17,06' S 19°20,42' W 4838 0,27 0,25 0,04 094 PS 1978-1 10.12.90 15:28 68°50,37' S 17°53,60' W 4795 0,10 0,09 0,04 096 PS 1979-1 11.12.90 04:30 69°22,01' S 16°29,80' W 4735 0,08 0,07 0,04 098 PS 1980-1 12.12.90 02:29 69°48,23' S 15°14,07' W 4741 0,04 0,00 0,00 100 PS 1981-1 12.12.90 11:35 70°07,90' S 14°15,21' W 4526 0,26 0,25 0,04 101 PS 1982-1 12.12.90 19:53 70°18,75' S 13°42,09' W 4366 0,26 0,25 0,04 102 PS 1983-1 13.12.90 02:16 70°23,27' S 13°32,57' W 2968 0,26 0,25 0,04 104 PS 1984-1 13.12.90 08:09 70°29,80' S 13°08,31' W 2407 0,26 0,25 0,25 106 PS 1985-1 13.12.90 16:38 70°47,72' S 12°22,24' W 2074 0,22 0,20 0,04 108 PS 1986-1 14,12.90 00:25 70°59,39' S 11°50,73' W 1135 0,23 0,21 0,04 114 PS 1987-1 15.12.90 14:37 71°04,87' S 11°33,72' W 273 0,20 0,19 0,04 118 PS 1988-1 23.12.90 17:42 54°19,84' S 03°24,10' W 2704 0,17 0,17 0,17 5.3. Particle flux in the water column E. Schöffmann M. Segl (FGB) Objectives To quantify the particle flux from the photic layer to the sediment and to monitor the seasonality of sediment build-up over several years. Work at sea At five positions moorings with sediment traps were deployed; two on the western and eastern slope (206 and KN4), one in the center of the Weddell Sea (208), west of Bouvet Island (B0 1) and in the area of the Polar Front (PF 4) (Figure 2.25). Three sediment trap moorings were recovered in the western and the central Weddell Sea and at the Polar Front (Figure 2.26). On board, smear slides were prepared from the trap samples. The samples were then stored in a cool room at 4°C. Further investigations on the sediment trap material including biological, geological and isotopic analysis will be carried out at the AWI and at the FGB. Preliminary results The sediment traps in the Weddell Sea operated since 20 September 1989 (mooring 206) and 5 November 1989 (mooring 208), respectively. The sample bottles were changed every 15 days in spring and summer and every 30 days during the winter. The trap in mooring 206 sampled only until May 1990 because of electronic problems. The upper trap in mooring 208 worked well, the lower trap did not work at all. The flux to the traps showed a maximum during February and March. The traps in the Polar Front operated since November 1989. The maximum flux was in March. In the upper trap, the cups from the winter months contained about 118 to 114 of the material that was collected in the summer months. In the lower trap the winter cups were nearly empty. This leads to the conclusion that in winter most of the material present in the photic zone is reworked in the water column and does not reach the sediment. 5.4. Stable isotopes in the water column E. Schöffmann M. Segl (FGB) Objectives Stable oxygen and carbon isotopes are used in marine geology to reconstruct the paleoceanographic history by measuring the 18O/16O and 13C/12C in the shells of marine organisms and the 13C/12C in the organic material, and to quantify the influence of bio-activity. Work at sea Samples to determine the isotopic composition of the dissolved CO2 (13C/12C) and of the water itself (18O/16O) were taken from the rosette on all biological stations. Samples of 250 ml and 100ml were put into glass bottles, avoiding air bubbles in the sample. The 250 ml samples for 13C measurements were poisoned with HgCl2 to avoid further CO2 production. These samples, as well as the 100 ml samples, were then sealed with wax and stored in a cool room at 4°C. The isotopic composition of the samples will be measured at the stable isotope laboratory of the AWI. Figure 2.25: Schematic representation of the mooring recovered in the Polar Front Figure 2.26: Schematic representation of moorings deployed in the Polar Front and West of Bouvet Island 5.5. Natural radioactive isotopes in the water column E. Schöffmann M. Segl (FGB) Objectives Investigations on sediment samples from the area off West Africa and from the Polar Front show that in areas with high biological activity, the flux of radioisotopes such as 10Be and 230Th to the sediments increases the production of the isotopes. This is due to scavenging of the isotopes by settling particles. This causes a concentration gradient of the isotopes from high to less productive areas which might allow former biological activity to be deduced. Work at sea To quantify these effects, samples for 10Be measurements were taken on 4 stations of the Weddell Sea transect. The investigations on these samples will be linked to investigations on 230Th in the Weddell Sea by the geochemistry group of the AWI, and to results of measurements of 10Be and 230Th in the South Atlantic by the FBG. To get the 30 l of water needed for a 10Be analysis, water from different depths within the same water layer was combined. A well known amount of 9Be carrier was added and Be, together with Mg and other elements, was precipitated at a pH of 8 - 9. The water was decanted, and the precipitate will be prepared for measurements with the accelerator mass spectrometer of the ETH Zürich. Additionally at all the minicorer-stations 10Be samples have been taken from the sediment surface. 6. POST INSTALLATION WORK ON THE COMPUTER SYSTEM H. Pfeiffenberger-PertI (AWI) Objectives A new central computer system and two local area networks were installed aboard "Polarstern" in October 1990. Five VAX-VMS systems of different capabilities, configured as a duster, replace one older VAX- VMS computer. The local area networks, using ethernet and localtalk cabling, provide the possibility to connect PCs and Workstations in all locations used for scientific purposes to each other, the central system and its resources, i.e. printers, plotters, etc. The most important objective of the work at sea was to observe this rather complex system under real conditions, in order to see - if the concepts leading to its hardware and software configuration do work, - how the system is utilized by the scientists, how its utility could be improved, - which problems are encountered and how to fix them. The result of this work should be a users manual for scientists and support personnel on board that provides advice on this specific installation in the most compact way possible. Work at sea The information necessary to meet the objectives was collected while giving advice or help to scientific users and support personnel. Some programming was necessary to fix problems, support routine operation of the system and to meet requests from scientists for access to specific data. The documentation most urgently needed was written. Preliminary results In general the VAX systems worked as planned. The most important task, the quasi-realtime data logging and processing on one of these machines, worked without problems. The disc and file services for PCs were made available on board in the same way as at the institute. Due to a much higher data transfer demand between VAX-, IBM-compatible and Macintosh-systems, yet unknown problems appeared. They could be solved by a file conversion utility and some documentation giving recipes. Observations on the use of publicly available PCs led to the conclusion that these will produce more work for the support personnel (or less utility to the scientists) than the VAX-systems, if - their users are not very disciplined and - they are managed as personal PCs Further work has to be done on this problem. 7. WEATHER CONDITIONS H. Erdmann, H. Köhler, H. Sonnabend (DWD) At the beginning of the cruise the main cyclonic activity was located west of the Antarctic Peninsula. On 17 November, the steering cyclone moved slowly eastward with a minimum pressure below 960 hPa. Secondary lows passed the Drake Passage quickly and affected "Polarstern" with northwesterly winds Bft 8 and seas up to 5 m. South of the Polar Frontal Zone, visibility deteriorated due to northerly winds Bft 7. On 20 November, "Polarstern" reached Bellingshausen Station with northwesterly winds Bft 7 and Snow showers. Due to catabatic influence, the wind increased up to Bft 9 near the station; in spite of the unfavorable weather conditions, helicopter service was possible. Due to the permanent influence of the wide-spread and stable low-pressure System with minimum pressure still below 960 hPa at the southwestern part of Bransfield Strait, wind turned from northwest to southeast Bft 5 on 21 November, while "Polarstern" left Bransfield Strait heading for the Weddell Sea. Snowfall coming up caused bad visibly later on and a decrease of air temperature down to -4°C. In the early evening, "Polarstern" approached an area densely covered with sea ice. During the following next four days, the ship operated within a low pressure area between the steering Weddell Sea cyclone and secondary lows in the north and northeast. Therefore, the pressure gradient as well as the winds were generally weak. Cold air mass advection gave rise to good visibility but was accompanied by some snow showers. On 26 and 27 November, the dominant cyclone remained stable over the northwestern Part of the Weddell Sea and began to fill slowly. Therefore, "Polarstern" was affected by stronger cold air advection in the northwestern section accompanied by numerous polar cumulonimbus clouds and heavy snow showers. On 28 November a new gale center developed in the western part of the Drake Passage and moved to the South Shetlands. On 29 November its frontal systems approached "Polarstern" near 66°S, 37°W while activity was decreasing. Therefore, wind turned northeasterly while decreasing to Bft 3 to 4. Occasionally occurring snowfall diminished visibility until the end of November. At the beginning of December, a flat high developed in the central Weddell Sea. Therefore, the wind was light and varying, the visibility very good and the clouds dissolved. A small-ranged but heavy cyclonic development north of "Polarstern's" operating area caused heavy snowfall on 3 December, which was accompanied by strong easterly winds up to force Bft 7. Therefore helicopter service was not possible on this day. During the night of 4 December, the cyclone moved south while decreasing and crossed the position of "Polarstern" to the west. The wind was backing to the north and caused low level warm air advection with rising dew point near 0°C. As a consequence, fog persisted for about 4 hours. On the same day, another but stronger cyclonic development evolved near South Georgia. This new storm center moved quickly southeast; with its rear and southerly gales up to force Bft 9 it affected "Polarstern" in the central Weddell Sea during 4 December. The maximum wind speed measured on board at the marine meteorological station was 55 knots within gusts. The chill temperature was -27°C and rendered open air work almost impossible. A small wedge within the advanced polar air gave rise to better weather conditions on 5 December but caused decreasing temperatures with morning minimum temperatures near -8°C. In the course of the next 3 days, weather remained fair, sometimes even sunny with only light winds generally from west, due to the influence of a relatively high pressure center north of. the ship's position. During the night hours, ice covering fog patches developed due to heat loss and disappeared when sun rose. In the eastern section of a quasi-stationary but developing low, strong warm air advection mainly in the upper troposphere produced widespread snowfall also in the operation area of "Polarstern" near 67°S, 23°W on 9 December. During the next 24 hours, temperatures rose to 0°C and wind turned northerly with force up to Bft 7. From 10 to 14 December, a dynamic high developed above the northern part of the Antarctic continent with its center (1004 hPa) near 70°S 05°W. Therefore, a strong Inversion near 1000 m-level caused overcast stratocumuli with some snow showers and light winds. On 15 December "Polarstern" reached Kapp Norvegia in sunshine and light winds produced by the still stationary high near Neuschwabenland. The weather conditions were still good when "Polarstern" was stationed at the shelf ice near Georg-von-Neumayer-Station for unloading. In spite of overcast sky with a ceiling near 800 feet and occasional "whiteout" conditions, helicopter service was not affected. When "Polarstern" left for Cape Town on 19 December, the synoptic situation changed. The dominant high at Neuschwabenland moved southwest while weakening and the low system east of South Georgia moved east. Therefore an easterly wind increased up to force Bft 6 accompanied with some snowfall and bad visibility. On 20 December "Polarstern" left the closely packed sea ice near 68°S, 03°W. On the southern edge of a heavy steering low near 60°S 05°W (958 hPa), which moved eastsoutheast very slowly, wind increased up to force Bft 7 to 8 while turning from east to southeast for some hours. Next day wind turned southwest while decreasing slowly. Wind seas and swell of about 3 m affected the voyage of "Polarstern" only little. On 24 December a new low developed northeast of South Georgia moving southeast slowly. Its frontal systems affected "Polarstern" on 25 December north of Bouvet Island with northerly gales Bft 8 to 9 turning northwest but decreasing slowly. Shortly before arrival in Cape Town, light winds, sunshine and warm temperatures were encountered. 8. ICE CONDITIONS H.-J. Brosin, D. Zippel (IfMW) Visual observations of the ice conditions were performed between 22 November and 20 December according to instructions given by the Glaciological Section of the Alfred-Wegener-Institute. Altogether 236 observations were realized together with an additional 70 observations on the distribution of algae in the ice. The first iceberg was observed on 20 November at the position 62°12'S, 57°56'W, the last one on 23 December. The ice edge was crossed at 63°30'S, 51°30'W 150 km distant from the nearest shoreline on 22 November. It was passed again at the position 68°S, 04°W on 20 December. The shelf ice edge was reached for the first time at 71°07'S, 11°23'W on 15 December. The portion of white ice amounted to 40 to 100% of the total ice cover. The thickness mostly varied between 0.5 and 1.5 m and was estimated to be up to 2 m in a few cases. A distinct increase of the size of ice floes to a diameter of more than 1 km was observed at the position 65°39'S, 39°W, an evident reduction of the floe size occurred only close to the end of the observations at 70°25'S 13°25'W. The thickness of the snow cover on the ice varied between 20 and 50 cm. Marked melting effects at the bottom layers of ice floes were observed for the first time at the position 66°22'S, 29°32'W On 2 December. Local new ice formation (nilas, grey-white ice) were repeatedly observed after a larger decrease in air temperature. A wide spread occurrence of icebergs was observed particularly at the western edge of the working area between 64° and 65°50'S, 49° and 40°W (up to 41 icebergs within the field of view) and at the southeastern edge from 69°15' to 70°30'S, 16°45' to 10°W (up to 52 icebergs seen simultaneously). 9. ACKNOWLEDGEMENTS When we left "Polarstern" in Cape Town, we felt that we had had an extremely successful cruise and an enjoyable life on board. We are aware that master Jonas together with officers and crew took good care of our needs with a dedication and patience which guaranteed efficient work and good humour. 10. REFERENCES Unesco, 1983. International Oceanographic tables. Unesco Technical Papers in Marine Science, No. 44. Unesco, 1991. Processing of Oceanographic Station Data. Unesco memorgraph By JPOTS editorial panel. 11. WHPO SUMMARY Several data files are associated with this report. They are the ANTIX.sum, ANTIX.hyd, ANTIX.csl and *.wct files. The ANTIX.sum file contains a summary of the location, time, type of parameters sampled, and other pertinent information regarding each hydrographic station. The ANTIX.hyd file contains the bottle data. The *.wct files are the ctd data for each station. The *.wct files are zipped into one file called ANTIX.wct.zip. The ANTIX.csl file is a listing of ctd and calculated values at standard levels. The following is a description of how the standard levels and calculated values were derived for the ANTIX.csl file: Salinity, Temperature and Pressure: These three values were smoothed from the individual CTD files over the N uniformly increasing pressure levels. using the following binomial filter- t(j) = 0.25ti(j-1) + 0.5ti(j) + 0.25ti(j+1) j=2....N-1 When a pressure level is represented in the *.csl file that is not contained within the ctd values, the value was linearly interpolated to the desired level after applying the binomial filtering. Sigma-theta(SIG-TH:KG/M3), Sigma-2 (SIG-2: KG/M3), and Sigma-4(SIG-4: KG/M3): These values are calculated using the practical salinity scale (PSS-78) and the international equation of state for seawater (EOS-80) as described in the Unesco publication 44 at reference pressures of the surface for SIG-TH; 2000 dbars for Sigma-2; and 4000 dbars for Sigma-4. Gradient Potential Temperature (GRD-PT: C/DB 10-3) is calculated as the least squares slope between two levels, where the standard level is the center of the interval. The interval being the smallest of the two differences between the standard level and the two closest values. The slope is first determined using CTD temperature and then the adiabatic lapse rate is subtracted to obtain the gradient potential temperature. Equations and Fortran routines are described in Unesco publication 44. Gradient Salinity (GRD-S: 1/DB 10-3) is calculated as the least squares slope between two levels, where the standard level is the center of the standard level and the two closes values. Equations and Fortran routines are described in Unesco publication 44. Potential Vorticity (POT-V: 1/ms 10-11) is calculated as the vertical component ignoring contributions due to relative vorticity, i.e. pv=fN2/g, where f is the coriolius parameter, N is the buoyancy frequency (data expressed as radius/sec), and g is the local acceleration of gravity. Buoyancy Frequency (B-V: cph) is calculated using the adiabatic leveling method, Fofonoff (1985) and Millard, Owens and Fofonoff (1990). Equations and Fortran routines are described in Unesco publication 44. Potential Energy (PE: J/M2: 10-5) and Dynamic Height (DYN-HT: M) are calculated by integrating from 0 to the level of interest. Equations and Fortran routines are described in Unesco publication 44. Neutral Density (GAMMA-N: KG/M3) is calculated with the program GAMMA- N (Jackett and McDougall) version 1.3 Nov. 94. 12. CTD DATA QUALITY EVALUATION Robert Millard November 27, 1995 ANTIX: CTD Data Quality Comments General: The range of potential temperature for the ANTIX data set is narrow (-1.87 to 1.89°C) and salinity varies from 33.92 to 34.72 psu. The potential temperature versus salinity plot for all stations is shown in figure 1. Removing station 121 reduces temperature/salinity range further with the warmest temperature below 0.9°C and the minimum salinity increased to 34.1 psu. I found the 2 decibar CTD data to be well calibrated to the water sample data and the data was also well edited to remove questionable data values. The informal CTD data documentation (I'm not referring to the Cruise report 17 edited by Eberhard Fahrbach) that accompanied the CTD data was sketchy and contained little information on processing procedures. It would be helpful to have more information on calibration and processing methods used with this data set. Perhaps there is a technical report available that can be referenced? An overall assessment of the quality of the CTD and water sample data, including a few plots, would be helpful. There is one figure (2.5) in the cruise report (17) comparing the Autosal and CTD salinities. The data assessment might have information such as which water sample data were used in for the CTD conductivity calibration. A more detailed data report along with more extensive use of the quality word to flagged data that are either questionable or altered both in the water sample file and individual 2 decibar station files would be helpful to secondary users of the data. There are no CTD oxygens in either the water sample or individual 2 decibar CTD data files. There is no assessment of the oxygen data in this report. The down profile 2 decibar CTD data are free of spurious data values as the density inversion check below indicate. The data quality word in the 2 decibar CTD data files is not always utilized. For example, an interpolation on station 50 for salinity is carried out between 4000 & 4500 decibars without flagging in the quality word. The CTD salinity observations are very well matched to the water sample data except as noted below. The CTD salinity in the water sample file differs from the down-profile salinity data and water sample salinities for many stations, particularly in the deep water. Specific comments on the CTD data processing documentation: Note: This is a separate document from the formal cruise Report 17 (July 1991) edited by Eberhard Fahrbach. The CTD conductivity calibration is varied on a station by station basis to matched the individual station water sample data. The conductivity calibration coefficients are smoothed over 10 stations without explanation. The correction of the CTD conductivity to match the water samples involves up to a fourth order polynomial in pressure. The coefficients of the conductivity correction polynomial are tabulated in the data documentation. I don't understand why it was necessary to use such a high order polynomial in pressure to obtain well calibrated CTD salinities. Are all of the pressure correction terms of these polynomials significant? Was the CTD conductivity cell geometry correction applied (see the formula below)? Were these corrections used and found not to work well? Again, more detailed in the data report would be useful. CTD Conductivity Cell geometry corrections as recommended by the manufacture. Were these applied to this data set along with a fourth order polynomial in pressure?? The CTD conductivity cell pressure and temperature deformation effects for the Mark III with an alumina conductivity cell are: C = G* (1+alpha* (T-T0) +beta* (P-P0)) where G = CTD conductance alpha = -6.5E-6 beta = 1.5E-8 T0 and P0 are expansion values. 2.8°C and 3000 dbars typically. We find that the conductance G drift can be modeled with a linear station dependent change conductivity slope variation (not always necessary) G = A+ B*g+C*g*s "g" = is the observed CTD conductance and "s" is station related. A = bias, B = slope and C = station dependent term. I found the data report description of the terms in the formula (see below) to be confusing. The conductivity correction term is referred to as both "CD and "dc'). What is the definition of CONDUCTIVITY SALINO: Is it the conductivity of the lab salinometer or is it an "instu conductivity derived from the water sample salinity by using the CTD temperature and pressure? ------------------- from informal CTD document ------------------ The following is taken from the ANTIX data report section that I found to be confusing as indicated by (????). dp = al +a2*p +a3*p**2 +a4*p**3 +a5*p**4 +a6*p**5 p = p + dp???? : This implies that dp = 0.0. (i.e. p-p=dp=0.0.) The same is true for t-t+dt ????. I think these corrections were meant to be p = pu + dp; where Pu is the uncorrected pressure. correction of the CTD-conductivity data with the bottle-samples (conductivity of the salinometer data) evaluation of the coefficients of each station ------------------------------------------------- CD = ( CONDUCTIVITY SALINO ???? - CONDUCTIVITY CTD ) * 1000 COND :== CONDUCTIVITY SALINOMETER ------------------------------------------------- CD = A0 + A1*COND + A2*PRES + A3*PRES**2 ------------------------------------------------- station no. A0 Al A2 A3 03501 -0.51872E±02 0.24728E±01 -0.63940E-02 0.79995E-05 dc = A0 + A1*COND + A2*PRES + A3*PRES**2 C(ctd) = C(ctd) + dc/1000. correction of the CTD-conductivity data with the bottle-samples evaluation of the coefficients with the running mean of 10 stations ------------------------------------------------- CD = A0 + A1*PRES + A2*PRES**2 + A3*PRES**3 + A4*PRES**4 Water sample file: The CTD salinity data in the water sample file is compared to the water sample salinities (CTD minus WS) and displayed versus station number for all depth levels in figure 2a and for those below 900 decibars in figure 2b. Individual stations such as stations 46, 47, 69, 75, 76, and 93 show large differences but a closer examination indicates that the problem is with the water sample data as the potential temperature/salinity plot shown in figure 3 for stations 68-78 indicates. It is difficult to know which water sample data were used for the CTD calibration as all water sample salinity data (i.e. column labeled "SALNTY" are flagged with "3" indicating that they are considered questionable). A histogram of the salinity differences (CTD-WS) less than =/- 0.01 psu is given in figure 4 and appears to have a reasonable distribution. The mean difference is -0.0005 psu and the standard deviation is 0.0028 psu both again appear reasonable. The plot of salinity differences (CTD-WS) versus pressure, figure 5, shows a slightly odd behavior at and below 3000 dbars. A clustering of positive salt differences, mainly below 4000 dbars, is apparent. The down-profile CTD salinities show no corresponding systematic behavior indicating perhaps that the polynomial pressure correction for conductivity was developed for the down-profile (should be addressed in the data documentation) and doesn't necessarily work well for the up-profile salinity data. These CTD salinities in the water sample file should be flagged as questionable. 2-decibar CTD profiles (___.WCT) The down-profile CTD salinities are well matched to the water sample salinities but this does not always carry over to the up-profile CTD salinities in the water sample file particularly in the deep waters (as mentioned already). A plot of down and up CTD and water sample salinities for stations 57-60 again illustrated the up salinity mismatch in figure 6 (circles are CTD salinity from WS file). These CTD salinities need to be flagged as questionable or bad (they are currently marked as good!!!). There are a number of salinity interpolations apparent in the 2 decibar data files. I found that stations 50, 58, 59, 64, and 74 had significant intervals in the deep water that appear to be interpolated (see figures 7a-d). There are probably others that I have missed. These need to flagged in the quality word (value =6) as described in the WHP Office Report 90-1 [see page 55] Finally the stability of all data points were checked and a plot of unstable levels in excess of -.001 kg/m3/dbar (x) and -0.0015 kg/m3 per decibar (*) are indicated in figure 8. Note that in the table below the units of density gradient are given as kg/m3 per 2 decibars corresponding to the vertical pressure interval. A list of the 47 point with negative density gradients exceeding -.002 kg/m3 per 2 decibars are given below. The data set is remarkably free of density inversions as only 3 levels exceeding -0.003 kg/m3 per 2 decibar. This is due, in part, to the narrow range of salinity and temperature variations in the vertical. The station numbers in the table includes a decimal location within the station. dsg/dp > -.002 kg/m3 per 2 decibar dsg/dp station # Prs dbars -4.1938465e-003 4.0111765e+001 5.9400000e+002 -3.8449577e-003 4.0140000e+001 7.3800000e+002 -2.2512519e-003 4.0143137e+001 7.5400000e+002 -2.0012428e-003 4.0152549e+001 8.0200000e+002 -2.2761947e-003 4.1328627e+001 1.6900000e+003 -2.2156429e-003 4.2094510e+001 5.0800000e+002 -2.0093994e-003 4.2159608e+001 8.4000000e+002 -2.0330352e-003 4.2175686e+001 9.2200000e+002 -2.0348226e-003 4.2204314e+001 1.0680000e+003 -2.0110160e-003 4.3222353e+001 1.1720000e+003 -2.0117508e-003 4.4061961e+001 3.5000000e+002 -2.0152598e-003 4.4666667e+001 3.4340000e+003 -2.0399616e-003 4.5290980e+001 1.5120000e+003 -2.0422801e-003 4.6274118e+001 1.4220000e+003 -2.4128358e-003 5.0011765e+001 1.0200000e+002 -3.1532004e-003 5.0012157e+001 1.0400000e+002 -2.9423388e-003 5.0014118e+001 1.1400000e+002 -2.0102297e-003 5.0050588e+001 3.0000000e+002 -2.1142905e-003 5.0091765e+001 5.1000000e+002 -2.0107781e-003 5.4066275e+001 3.7800000e+002 -2.0113735e-003 5.4103529e+001 5.6800000e+002 -2.0107581e-003 5.5083137e+001 4.6600000e+002 -2.0106812e-003 5.7069020e+001 3.9800000e+002 -2.0123969e-003 6.1210196e+001 1.1340000e+003 -2.1120462e-003 6.6076863e+001 4.5600000e+002 -2.0108038e-003 6.6121569e+001 6.8400000e+002 -2.9807854e-003 6.7989804e+001 1.4000000e+001 -2.0106718e-003 6.8101176e+001 5.8400000e+002 -2.7478252e-003 6.9962745e+001 4.9900000e+003 -2.0130675e-003 7.1242745e+001 1.3120000e+003 -2.4672703e-003 7.4006667e+001 1.1400000e+002 -2.3746039e-003 7.4009804e+001 1.3000000e+002 -2.5816618e-003 7.5010196e+001 1.3400000e+002 -2.6604134e-003 7.5014902e+001 1.5800000e+002 -2.0106403e-003 7.5127843e+001 7.3400000e+002 -2.8358944e-003 7.9002353e+001 1.1200000e+002 -2.1278849e-003 8.1022353e+001 2.2000000e+002 -2.0105649e-003 8.2118824e+001 7.1400000e+002 -2.7795357e-003 8.4012157e+001 1.7400000e+002 -2.0654205e-003 9.1005882e+001 1.5400000e+002 -2.1225245e-003 9.2053725e+001 3.9800000e+002 -2.0096993e-003 9.2153725e+001 9.0800000e+002 -2.0536578e-003 9.3014510e+001 2.0200000e+002 -2.0068535e-003 9.3068235e+001 4.7600000e+002 -2.0090439e-003 9.3144706e+001 8.6600000e+002 -2.0314412e-003 9.4152941e+001 9.1000000e+002 -2.0321519e-003 9.4164314e+001 9.6800000e+002 -2.0107911e-003 9.7218039e+001 1.2480000e+003 -3.8238614e-003 9.9976078e+001 8.0000000e+000 -2.0341040e-003 1.0017843e+002 1.0420000e+003 -2.0276837e-003 1.0111961e+002 7.5400000e+002 dsg/dp > -.0015 kg/m3/dbar dsg/dp station # Prs dbars -4.1938465e-003 4.0111765e+001 5.9400000e+002 -3.8449577e-003 4.0140000e+001 7.3800000e+002 -3.1532004e-003 5.0012157e+001 1.0400000e+002 -3.8238614e-003 9.9976078e+001 8.0000000e+000 13. CCHDO DATA PROCESSING NOTES Date Person Data Type Action Summary ---------- --------- ------------ -------------- ---------------------------------- 1999-03-15 Diggs, S. He/Tr/Ne Submitted not yet merged w/ btl data SR04 (06AQANTIX_2): we now have unmerged Helium, Neon and Tritium data for this repeat. 2001-05-30 Uribe, K. BTL Website Update Exchange file online Bottle has been put into exchange format. There was a station/cast number 121 not included in the bottle file which was removed from the sumfile in order to put the data into exchange. Bottle and sumfile links on website remain the same new exchange file has been added to website. 2001-12-12 Uribe, K. CTD Website Update Exchange file online CTD has been converted to exchange using the new code and put online. 2012-08-15 Barna, A. He/Tr Website Update Available under 'Files as received' File Ant9_2.woc containing Helium and Tritium data, submitted by Dr. Birgit Klein via email on 1999-03-12, available under 'Files as received', unprocessed by CCHDO. 2013-07-10 Berys, C. HE-TRIT Website Update Exchange, NetCDF, WOCE files online =========================================================== 06AQANTIX_2 processing - BTL/merge - HELIUM, TRITUM, DELHE3 =========================================================== 2013-07-10 C Berys .. contents:: :depth: 2 Submission ========== ========== ============ ========== ========= ==== filename submitted by date data type id ========== ============ ========== ========= ==== Ant9_2.woc Birgit Klein 1999-03-12 He/Tr None ========== ============ ========== ========= ==== Parameters ---------- Ant9_2.woc ~~~~~~~~~~ - CTDPRS - CTDTMP - CTDSAL [1]_ - SALNTY [1]_ - OXYGEN [1]_ - SILCAT [1]_ - NITRAT [1]_ - NITRIT [1]_ - PHSPHT [1]_ - TRITUM [1]_ - HELIUM [1]_ - DELHE3 [1]_ - NEON [1]_ - NEONER - HELIER - TRITER - DELHER .. [1] parameter has quality flag column Process ======= Changes ------- Ant9_2.woc ~~~~~~~~~~ - converted to WHP Exchange format - TRITIUM changed to TRITUM - DELHE3 and DELHER units changed from % to PERCNT Merge ----- Ant9_2.woc ~~~~~~~~~~ Merged Ant9_2.woc into sr04_b_hy1.csv using hydro 0.8.0-10-ge326027 :New parameters: HELIUM, HELIUM_FLAG_W, NEON, NEON_FLAG_W, NEONER, TRITER, HELIER, TRITUM, TRITUM_FLAG_W, DELHER, DELHE3, DELHE3_FLAG_W All comment lines from original file copied back in following merge. sr04_b_hy1.csv opened in JOA with no apparent problems. Conversion ---------- ================= ======================== ======================= file converted from software ================= ======================== ======================= he-trit_hy1.csv Ant9_2.woc, sr04_bsu.txt hydro 0.8.0-10-ge326027 sr04_b_nc_hyd.zip sr04_b_hy1.csv hydro 0.8.0-10-ge326027 sr04_bhy.txt sr04_b_hy1.csv hydro 0.8.0-10-ge326027 ================= ======================== ======================= All converted files opened in JOA with no apparent problems. Directories =========== :working directory: /data/repeat/southern/sr04/sr04_b/original/2013.07.10_HE-TRIT_CBG :cruise directory: /data/repeat/southern/sr04/sr04_b Updated Files Manifest ====================== - sr04_bhy.txt - sr04_b_nc_hyd.zip - sr04_b_hy1.csv 2013-07-12 Berys, C. CTDTMP-UNITS Website Update Corrected Exchange, netCDF and WOCE files online ====================== 06AQANTIX_2 processing ====================== 2013-07-12 C Berys .. contents:: :depth: 2 Process ======= Changes ------- - CTDTMP units changed from 'ITS-90' to 'IPTS-68' Conversion ---------- ================= ============== ======================= file converted from software ================= ============== ======================= sr04_b_nc_hyd.zip sr04_b_hy1.csv hydro 0.8.0-10-ge326027 ================= ============== ======================= All converted files opened in JOA with no apparent problems. Directories =========== :working directory: /data/repeat/southern/sr04/sr04_b/original/2013.07.12_CTDTMP-UNITS_CBG :cruise directory: /data/repeat/southern/sr04/sr04_b Updated Files Manifest ====================== - sr04_bhy.txt - sr04_b_nc_hyd.zip - sr04_b_hy1.csv 2013-10-23 Kappa, J. CrsRpt Website Update Updated TXT version online I have added a new version of the cruise report: sr04_bdo.txt to the directory http://cchdo.ucsd.edu/data/repeat/southern/sr04/sr04_b/ Updates include • CTD data report, • CTD DQE report by Robert Millard • CCHDO Summary Page • Data Processing Notes.