R/V Chofu Maru Cruise NC9401 1 Cruise Narrative 1.1 Highlights Expedition Designation Chofu Maru Cruise NC9401 Chief Scientist Kan Kimura, NMO Ship R/V Chofu Maru Port of Call None Cruise Dates Leg 1: January 18 to January 24, 1994 1.2 Cruise Summary Observations of PR18 were carried out as a part of the R/V Chofu Maru Cruise NC9401 Leg 1. The ship sailed from Nagasaki at 0600 UTC on 18 January, 1994. By 1012 UTC on 19 January, the ship was at the first station of a section PR18. The cruise track and station locations are shown in Figure 1. The observations of PR18 finished at 1141 UTC on 21 January. Water sampling on the cruise included measurements of salinity both by CTD and by water bottle samples, CTD temperature, bottle sample oxygen determination, and nutrients (nitrates, nitrites, and phosphates). 1.3 Principal Investigators for All Measurements The principal investigators for all the parameters measured on the cruise are listed in Table 1. Table 1. Principal Investigators for All Measurements Name Responsibility Affiliation T. Tomiyama CTD,S NMO K. Kimura O2,Nutrients NMO 1.4 List of Cruise Participants The cruise participants are listed in Table 2. Table 2. Cruise Participants Name Responsibility Affiliation NC9401 Leg 1 Nagasaki to Naha 18 Jan. to 24 Jan. K. Kimura Chief Scientist, NMO O2,Nutrients T. Hinata CTD Software NMO T. Shiga S NMO N. Nagai O2 NMO T. Shimizu O2,Nutrients NMO J. Jifuku O2,Nutrients NMO T. Chagihira CTD Software NMO M. Suzuki CTD Hardware NMO H. Fukushima Maritime Meteorology NMO Y.T 2. CTD The NBIS Mark III B CTD (1600 dbar sensor without oxygen sensor) mounted on the 12 x 1.7 Liter General Oceanics rosette multisampler frame was used for all of the vertical CTD work. The performance of the CTD and multisampler were good throughout the cruise. The details of the data collection and data processing methods are described in "CTD Full Sampling and Data Processing Method Used at Nagasaki Marine Observatory". These methods were based on Millard and Yang ( 1992 ). The results of the laboratory calibration for the temperature and pressure are shown in Table 3. Table 3. CTD calibration constants at laboratory Temperature; linear fit Time Bias Slope Pre -Cruise 6 Oct. 1993 0.0001789 1.0000217 Pressure increasing (0-1600 dbar range); linear fit Time Bias Slope Pre -Cruise 6 Oct. 1993 -0.5510073 0.9990991 Pressure decreasing (0-1600 dbar range); linear fit Time Bias Slope Pre -Cruise 6 Oct. 1993 -1.4895741 0.9998088 The conductivity scaling factor given in Table 4 is derived from a linear fit of CTD data to water sample data and were used for the final data load. The salinity determination of the water samples was with the Guildline AUTOSAL 8400A. Standard Seawater batch of P121 was used to standardize the AUTOSAL. The precision of the salinity determination of the water samples was 0.0002 PSS derived from the standard deviation of the twenty-one water samples collected from the same bottle. Table 4. The conductivity scaling factor; linear fit Station No. Bias Slope PN-1 - PN-9 0.003349 0.999866 A temperature time lag was decided using the CTD time constant decision program, time lag was 0.192 seconds. The ITS-90 scale was used for the temperature and potential temperature scale. Y.T 3. Oxygen measurements The determination of dissolved oxygen was done by the modified version of the Winkler method described in "Kaiyou kansoku shishin (Manual of Oceanographic Observation)" published by the Oceanographical Society of Japan (1970). The reagent blank was not subtracted. The results of the estimation of precision are shown in Table 5. No estimation of accuracy has been made. Table 5. The precision of oxygen analyses by four analysts Sample Number Average One sigma precision umol/l umol/l % Analyst A 10 217.7 0.28 0.13 Analyst B 10 218.2 0.15 0.07 Analyst C 10 218.4 0.31 0.14 Analyst D 10 218.5 0.13 0.06 K.K 4. Nutrient analyses The nutrients analyses were done by the Technicon Auto Analyzer II described in "Kaiyou kansoku shishin (Manual of Oceanographic Observation)" published by the Oceanographical Society of Japan (1970). Sampling for nutrients followed that for dissolved oxygen on average 10-20 minutes after the casts were on deck. Samples were drawn into 10 cm3 glass, narrow mouth, screw-capped bottles. Then they were immediately introduced on the sampler tray of the Technicon Auto Analyzer II for the analysis and generally the analyses were begun within one hour after the casts were on deck. If the delays were anticipated to be more than one hour, the samples were refrigerated. Samples were refrigerated and stored up to one hour on stations PN-9, PN-7, PN-4', PN-4 and PN-3'. The precisions of the onboard Nitrate and Nitrite analyses estimated from the standard deviation of the five samples from the same working standard solution on each analysis are shown in Table 6. The precision of the onboard Phosphate analysis estimated from the standard deviation of the five samples from the same working standard solutions are also shown in Table 6. The concentrations of the working standard of nitrate, nitrite and phosphate were 40 umol/l, 2 umol/l and 3 umol/l, respectively. No estimation of accuracy have been made. Table 6. The median and the range ( in the parentheses ) of the precision of the onboard nutrients analyses. Nitrate Nitrite Phosphate unit:% 0.390 0.209 0.539 (0.264-0.793) (0.079-0.515) (0.239-0.771) The concentrations in umol/kg of oxygen, nitrate, nitrite and phosphate were converted from the concentrations in umol/l using the density calculated from the room temperature and salinity of the water samples. The laboratory temperature for each station are given in Table 7. Table 7. Laboratory temperature for each station.*********** Station Temp. Station Temp. Station Temp. PN-9 31.3 PN-8 31.3 PN-7 31.1 PN-6 31.1 PN-5 30.5 PN-4' 31.7 PN-4 30.4 PN-3' 29.4 PN-3 29.6 PN-2 29.8 PN-1 31.6 K.K 5. Notes for the --.SUM, --.SEA and --.CTD files The first 2 characters of the file name of --.SUM, --.SEA and --.CTD files are NC for R/V Chofu Maru of Nagasaki Marine Observatory. These characters are followed by the last two digits of year, the month and character R (R for PR18) or character S (S for PR19) for the --.SUM and --.SEA files. In addition, the leg of the cruise is appended in the file name of --.SEA files. For the -- .CTD files the characters NC are followed by the unique station number and the cast number given in the Comments. The file names of the --.SUM and --.SEA for this cruise are as follows; NC9401R.SUM, NC9401R1.SEA 5.1 --.SUM Since some of the water depth of the cast were not recorded, we leave the column of them blank. Since the surface water samplings were by a stainless steel water bucket, "Number of bottles" includes this bucket sampling. The unique station numbers given by the Japan Meteorological Agency with the cast numbers, which are used as the --.CTD files name, are given in the "Comments". 5.2 --.SEA We leave "the sample number (SAMPNO)" blank because the sample numbers are different among the salinity, oxygen and nutrients on our assignments. Since the surface water samplings were by a stainless steel water bucket, we leave the column of "The Bottle Number (BTLNBR)" at the surface layer blank. All water sample quality flags for the oxygen during this cruise were "3" because the precision did not exceed the WOCE standard of 0.1% and no estimation of accuracy has been made. 5.3 --.CTD The files name were given in the Comments of --.SUM files. Y.T 6. GPS For examine the accuracy of the position data of the GPS systems, standard deviations were calculated in after cruise. The position data were good throughout the cruise. The results are shown in Table 8. Table 8. Standard deviation of position data Date Port Standard deviation Latitude Longitude Jan. 18 Nagasaki 18.3m 18.3m Y.T 7. References Aoyama,M, S.Saito, T.Kobuchi and S.Shiraishi, 1993: CTD full Sampling and Data Processing Method Used at Nagasaki Marine Observatory. (Draft) Millard,R and Keqi Yang, 1992: CTD Calibration and Processing Methods used by Woods Hole Oceanographic Institution.(Draft) Oceanographical Society of Japan, 1970: Kaiyou kansoku shishin (Manual of Oceanographic Observation). Ed. by the Japan Meteoro- logical Agency. (in Japanese)