A. Cruise Narrative A.1 Highlights A.1.a WOCE designation Leg 1: PR6, PRS1, and P15N Leg 2: P15N A.1.b EXPOCODE Leg 1: 18DD9403/1 Leg 2: 18DD9403/2 A.1.c Chief Scientist Leg 1: John Garrett Institute of Ocean Sciences P.O. Box 6000 9860 West Saanich Road Sidney, B.C. V8L 4B2 Canada Telephone: 604-363-6574 Telefax: 604-363-6479 Leg 2: Howard Freeland Institute of Ocean Sciences P.O. Box 6000 9860 West Saanich Road Sidney, B.C. V8L 4B2 Canada Telephone: 604-363-6590 Telefax: 604-363-6746 A.1.d Ship John P. Tully A.1.e Ports of call Leg 1: Dutch Harbor, Alaska to Honolulu, Hawaii Leg 2: Honolulu, Hawaii to Pago Pago, American Samoa. A.1.f Cruise dates Leg 1: Sept. 6 to Oct. 10, 1994 Leg 2: Oct. 13 to Nov. 10, 1994 A.2 Cruise Summary Information A.2.a Geographic boundaries On September 6, the Tully sailed west from the mouth of Juan de Fuca Strait, along Line PR6. After completing 4 stations en route to Station PRS1, the vessel sailed for Dutch Harbor, Alaska, where it refueled. Section P15N started near Dutch Harbor and continued south along 165 W. At 24 N, we gradually shifted towards the West to coincide with a previous NOAA section and the planned route of P15S. Most of the scientific crew were changed in Honolulu after 35 days at sea. Leg 2 continued from 20 30 N, following a course that moved gradually westward to 168 45 W at 10(N. We remained on this longitude through the equator, then began a second southwestward course at 8 30 S that took us to 170 W at 10 S. At 15 S, Leg 2 ended and the vessel sailed to American Samoa. A.2.b Stations occupied CTD/rosette casts were done at 3 stations along PR6, PRS1 was reoccupied, and 70 CTD/rosette stations along P15N were done during the first leg. Two rosettes were used to collect 3225 samples for onboard analyses of salinity, oxygen, nutrients, CFCs, total CO2 and alkalinity. Additional samples were stored for 13C, 14C, 18O and CH4. Continuous measurements of air and seawater CO2 were taken from the scientific seawater supply (Uncontaminated Sea Water). USW was also sampled for salinity, nutrients and chlorophyll a at almost all cast stations, and each degree of longitude between PRS1 and Dutch Harbor. Tracers were occasionally collected from the USW supply. Table 1: Station Locations for USW ----------------------------------- -123.500000 48.266700 -124.002500 48.299800 -124.500300 48.449800 -125.011700 48.539300 -125.546800 48.578200 -126.000000 48.600000 -126.333300 48.616700 -126.665700 48.649200 -126.171700 48.693300 -127.686700 48.743300 -128.666700 48.816700 -129.165800 48.856200 -129.662000 48.892700 -130.166700 48.933300 -130.661700 48.966700 -131.664700 49.044000 -132.664500 49.122500 -133.659200 49.200000 -134.669700 49.283700 -135.670000 49.350000 -136.661500 49.415300 -137.666700 49.650700 -138.667200 49.566500 -139.666700 49.633000 -140.662700 49.701200 -141.669500 49.767000 -142.658300 49.835000 -143.603200 50.000000 -144.303700 50.001200 -144.984500 50.003000 -146.009200 50.206300 -147.003500 50.401000 -148.009500 50.596000 -149.003800 50.786500 -150.008300 50.979700 -151.218300 51.208300 -152.007300 51.359700 -153.007000 51.550000 -154.061500 51.748200 -155.000800 51.924500 -156.001500 52.112200 -157.000000 52.295500 -158.021700 52.488300 -159.000200 52.666800 -160.117800 52.874800 -161.128300 53.041700 -162.024200 53.183000 -163.000200 53.286800 -164.000800 53.394300 -164.998300 53.640800 -164.989500 53.920700 -164.989300 53.744700 -164.995700 53.500300 -165.015000 53.249000 -165.003700 52.998200 -165.003000 52.739800 -165.495700 52.238000 -165.141700 51.358300 -164.990800 50.967200 -164.993200 50.499000 -165.003000 50.000300 -164.999000 49.493500 -165.007300 49.004200 -165.000000 48.500200 -164.999300 47.999500 -164.991500 47.503800 -164.995500 47.012700 -165.000300 46.498000 -164.999700 45.991800 -165.162700 45.504000 -164.755700 44.996700 -164.790200 44.500200 -164.995200 43.995000 -165.009300 43.487200 -164.990000 43.013300 -164.999200 42.500000 -164.995200 41.999700 -164.997200 41.496800 -165.005800 40.997700 -165.023300 40.494300 -165.000000 40.001300 -164.907200 39.498200 -165.000300 38.999200 -164.998300 38.504800 -165.003300 37.998300 -165.001800 37.501800 -164.999300 36.998000 -165.006200 36.504700 -165.002000 35.998000 -165.004200 35.495000 -164.995300 35.000800 -165.000800 34.514700 -164.993800 34.001300 -165.000200 33.496300 -165.014500 32.995300 -164.995800 32.505000 -164.995700 31.997700 -165.006000 31.503200 -165.006500 31.003700 -165.000700 30.503200 -164.984300 30.006700 -164.994500 29.504500 -164.994200 29.001800 -165.000800 28.503700 -164.998700 27.999800 -164.974300 27.512700 -164.994200 27.008500 -165.001500 26.499200 -165.005800 25.995000 -164.996500 25.505000 -164.998500 25.005300 -165.000800 24.498200 -164.997000 23.995200 -165.317700 23.504800 -165.463200 22.917000 -165.567500 22.500700 -165.703200 21.986800 -165.994700 20.899200 -158.548000 21.178300 -166.086200 20.508800 -166.189300 20.016700 -166.317200 19.502200 -166.439200 19.002500 -166.691000 18.001500 -166.843200 17.479700 -166.994300 16.970500 -167.108200 16.494800 -167.228200 15.993000 -167.349800 15.498300 -167.496500 14.998800 -167.616300 14.494800 -167.750200 13.976200 -167.871200 13.493000 -167.982800 13.000300 -168.118800 12.496000 -168.250200 11.996200 -168.375300 11.493800 -168.512000 11.006300 -168.623200 10.499500 -168.746000 10.006800 -168.749000 9.494200 -168.751000 8.996300 -168.754300 8.501000 -168.743300 8.001800 -168.741200 7.493500 -168.730700 7.002800 -168.726200 6.503500 -168.742000 6.001800 -168.739300 5.478000 -168.747300 4.997300 -168.752000 4.484700 -168.750200 4.007200 -168.747700 3.496500 -168.760000 3.004200 -168.755700 2.523300 -168.750300 2.010200 -168.762200 1.521500 -168.753200 1.009300 -168.760700 0.489000 -168.750700 -0.003200 -168.752500 -0.510800 -168.747800 -1.011800 -168.750700 -1.506800 -168.742800 -2.010300 -168.749000 -2.506800 -168.757000 -3.003300 -168.741200 -3.496300 -168.754800 -3.997800 -168.742200 -4.489200 -168.752800 -5.004700 -168.755200 -5.503800 -168.759200 -6.018000 -168.755800 -6.503800 -168.746000 -7.013000 -168.747800 -7.500500 -168.747200 -8.008300 -168.747200 -8.503500 -169.000200 -9.003500 -169.004200 -9.507300 -169.501300 -10.002300 -170.015500 -10.498200 -169.997500 -11.004300 -170.000000 -11.506500 -170.494200 -11.999000 -169.991500 -12.503800 -169.988500 -13.019000 -169.995300 -13.498800 -169.995500 -14.007200 -169.998300 -14.497500 -169.999500 -15.001300 ---------------------------- A.2.c Floats and drifters deployed At 4 stations, a total of 15 Argos drifters, 7 shallow (20 m drogues) and 8 deep (120 m drogues), were deployed. A single meteorological drifter was deployed for Department of the Environment near 47 N. About 2 dozen wine bottles with postcards inside were deployed at locations selected by a local school class. A.2.d Moorings deployed or recovered No moorings deployed or recovered A.3 List of Principal Investigators TABLE 2: Principal Investigators Principal Investigator Parameters Institution ----------------------------------------------------------------------- Howard Freeland Climate change, XBTs, IOS ADCP C.S. Wong Climate chemistry IOS TCO2, AT, CFCs, 13C, 14C, 18O, underway pCO2 Ron Perkin Physical measurements IOS CTD, salinity Frank Whitney Chemical measurements IOS Oxygen and nutrients, chlorophyll a, meteorology, bathymetry, thermosalinograph ----------------------------------------------------------------------- A.4 Scientific Programme and Methods Features such as the Alaska Stream, sub-arctic front, 2200 m silicate maximum (37 to 43 N), shallow oxygen minimum north of the equator, equatorial upwelling, flow of Antarctic water through the Samoan Gap, etc. are readily identified in this data set. Surface waters in the subarctic region of the Pacific are evidently a strong sink for CO2 in September. Our deep ocean winch, rosette/CTD and heave compensation equipment worked very well to 6000 m, the first test it has had below 4200 m. Sampling from the Tully was equally successful. The ship was able to hold station in 40 knot winds, and aft deck sampling proved comfortable and safe in most conditions. Sampling was suspended whenever the rosette unweighted excessively, as recorded on a load sensor mounted between the rosette and cable. A.5 Major Problems and Goals not Achieved Several stations were omitted due to high winds (reaching 70 knots), and CTD casts only were attempted at another 12 stations in marginal conditions. Thus there is a gap in the hydrographic sampling between 47 N and 43 30 N. Sampling intervals were spaced to 250 or 500 m below 3000 m at many stations, allowing us to save time by carrying out only a single rosette cast. This spacing should result in negligible loss of information, since there is little structure in North Pacific deep waters. Our deep ocean winch was damaged beyond repair following a cast at 10 S. Subsequent sampling was restricted to a maximum depth of 3800 m. CFC instrumentation caused us continual grief, although about 75% of the stations were successfully analyzed. We had to return to Honolulu to pick up a replacement Gas Chromatograph at the beginning of Leg 2, costing us 3 days of ship time. There were some difficulties encountered throughout the cruise that hampered obtaining optimal results for CFC-11 and CFC-12. A problem with the consistency of the quality of the carrier gas meant having to subtract higher than normal stripper blanks. The results of stations 83 to 97 may show zero at the 300 to 400 m depth because the threshold was initially set as per the 5890 GC program. This was modified for later stations in order to have very small peaks integrated. Thus these zero values may be a factor of threshold setting rather than a complete absence of CFCs. During some of the earlier stations we encountered samples affected by some sort of interference. This resulted in the F11 peak being split or at other times summed, usually in the fifty meter sample. Neither using the split value or a summed value seemed to give a reasonable result so these samples were flagged as questionable or bad. This problem was also encountered on the first leg of the cruise. Phosphate samples were frequently contaminated during the second half of the first leg. A nitrate reagent containing phosphoric acid was spilt on September 30 when Stations W044, W045, and W046 were analyzed. On October 1 it was noted in the nutrient log that the crew were washing the deck with soap - Stations W047, W048 and W049 were analyzed on this day. Our water demineralizing system failed during Leg 2, which forced us to use low nutrient sea water 1) to establish a baseline during analyses, and 2) for the preparation of standards. Each day, a sample of 3.2% NaCl in double run Milli-Q water was analyzed to assess the zero concentrations for each nutrient. Silicate and phosphate in wash water typically was 2 and 0.2 mM higher than the clean salt water solution. All data have been corrected for this baseline offset. LNSW was also used as a rinse after acid cleaning. The nitrite line developed a problem with crystal buildup at Station W123 and continued to the end of the cruise. This resulted in higher than expected values for deep samples and all data for Stations W123 - W137 has been labelled data quality 3 for both nitrite and nitrate. Nitrate data is questionable due to the doubtful subtraction of 0.1 to 0.3 umol/kg nitrite. A.6 Other Incidents of Note A.7 List of Cruise Participants TABLE 3: Cruise Participants Individual Responsibility Institution -------------------------------------------------------------------- Leg 1: John Garrett chief scientist IOS Frank Whitney coordinator, hydro. data IOS Dario Stucchi CTD data processing IOS John Love electronics, sampling, salinity IOS Bernard Minkley sampling, salinity IOS Reg Bigham sampling IOS Tim Soutar sampling IOS Ron Bellegay sampling IOS Valerie Knight carbonates IOS Galina Pavlova carbonates POI Linda White nutrients IOS Andrei Andreev nutrients POI Pavel Tishchenko CFCs POI Ruslan Chichkin CFCs POI Leo Rebele CFCs student Sarah Thornton Oxygen student Marie Robert sampling IOS Louise Timmermans sampling student Mary-Beth Derube sampling IOS Leg 2: Howard Freeland chief scientist IOS Ron Perkin CTD data IOS Bernard Minkley hydro data IOS John Love electronics, sampling, salinity IOS Reg Bigham sampling IOS Neil Sutherland sampling IOS Dennis Sinnott sampling IOS Hugh Maclean sampling UBC Keith Johnson carbonates IOS Marty Davelaar carbonates IOS Janet Barwell-Clarke nutrients IOS Mary OBrien nutrients IOS Wendy Richardson CFCs IOS Carol Stewart CFCs IOS Tracy Feeney CFCs student Bob Wilson Oxygen IOS Taimi Mulder sampling student Rhiannon Johnson sampling student Robin Brown sampling IOS Abbreviations: IOS Institute of Ocean Sciences, Sidney, B.C. Canada POI Pacific Oceanological Institute, Vladivostock, Russia UBC University of British Columbia Vancouver, B.C. Canada B. Underway Measurements B.1 Navigation and bathymetry A SAIL (Standard ASCII Interface Loop) system onboard ship poles several sensors at 2 min intervals. Data is stored on a micro computer and is subsequently processed in a format that is accessible for general use. Ships speed, heading, and position plus ocean depth are logged. B.2 Acoustic Doppler Current Profiler (ADCP) A hull mounted current profiler logged upper layer currents every 5 min throughout the cruise. B.3 Thermosalinograph and underway dissolved oxygen, etc Temperature and conductivity sensors are installed near the intake of a sea water line that is used as a scientific supply in the laboratory. Data is logged on SAIL. Uncontaminated Sea Water (USW) was continuously pumped to the laboratory and used for half hourly measurements of pCO2, continuous fluorometry (chlorophyll a) and discrete sampling at stations. An infrared analyzer was used to measure air, sea water and standard CO2 concentrations every 30 minutes throughout the cruise. Sea water was equilibrated within a trapped air space to provide samples for measurements of pCO2 in surface sea water (DOE 1994). Chlorophyll a samples were collected from the USW supply at most stations, and filtered through Whatman GF/F filters. Samples were then frozen for transport back to IOS. B.4 XBT and XCTD XBTs (Type T-5, 1830 m) were used at several stations when bad weather prevented use of CTDs. B.5 Meteorological observations Logged on SAIL are wind speed and atmospheric pressure. B.6 Atmospheric chemistry C. Hydrographic Measurements C.1. Water sampling 1. A 23 bottle rosette with a Guildline Model 8737 CTD was our primary sampling system (Niskin bottles numbers 1 to 23). 2. An 11 bottle rosette with a Guildline 8705 CTD was used for shallow casts (Niskin bottles number S1 to S11). Water samples were collected from rosettes by both CFC analysts (Freons only) and sampling teams. Samples were drawn in the order CFCs, oxygen, carbonate suite (TCO2, alkalinity, 13C, 14C) and methane, then nutrients, salinity and 18O in any order. CFC samples were drawn into 100 ml glass syringes that were thoroughly rinsed in a continuous stream of sample. CFC samplers checked each Niskin bottle for leaking by pushing in the sample spigot before opening the air vent. Gas samples were drawn through amber or Tygon tubing and were all allowed to overflow from one to two volumes. Carbonate samples were poisoned with 200 ml of saturated HgCl2 solution per 250 ml. Methane samples were drawn through amber tubing into glass bottles. Rubber septa with syringe needles piercing their centers, were used to eliminate air from the samples. Septa were crimp sealed in place and samples were refrigerated. Other sample containers were rinsed 3 times and filled as required. Nutrient samples were refrigerated until analysis. Salinity samples were warmed to lab temperature before being analyzed. 180 samples were tightly stoppered and refrigerated. Standard Deviation of Pairs (Sp) Standard Deviations of Pairs (Sp) were calculated from replicates drawn from Niskin bottles tripped within 2.3 db of each other using the following formula. Sp = {(summation of d**2)/2k}**0.5 where d = differences between pairs and k = number of pairs. Using this as a measure of precision includes all discrepancies introduced by leaking water samplers, sample collection, sample storage and analysis. TABLE 4: Standard Deviation of Pairs (Sp) Parameter Range Sp k ----------------------------------------------------------- Salinity (PSS-78 ) 33.576 - 35.923 0.003 46 Oxygen (umol/kg) 20.86 - 203.41 1.02 45 Silicate ( umol/kg) 0.02 - 149.8 0.34 46 Nitrate (umol/kg) 0 - 42.9 0.11 44 Nitrite (umol/kg) 0 - 1.406 0.008 46 Phosphate (umol/kg) 0.04 - 3.13 0.02 46 CFC-11 (pmol/kg) 0.415 - 2.587 0.076 11 CFC-12 (pmol/kg) 0.263 - 1.359 0.040 11 ----------------------------------------------------------- C.2 WOCE Line P15N: CTD Calibrations The P15N data was calibrated and processed to the stage of one metre average files using laboratory calibrations done before and after the cruise. The data were then examined for changes which may have occurred during the cruise, consistency between the three CTD’s used and agreement with bottle salinities. The findings are given below. Instruments The three CTD’s used were all Guildline CTD’s, the primary instrument being the WOCE model (WOCE CTD) which was used for most of the deep casts using the 24 bottle rosette. The 12 bottle rosette used for shallow casts was equipped with a standard Guildline Digital CTD (OP CTD sn 58483). In weather too rough for launching a rosette, a modified Guildline Digital CTD was used (CTD6). WOCE CTD, Guildline Model 8737 , SN 59901 This CTD was used for most of the casts in this cruise usually mounted in a bottle slot on a custom made 24 bottle rosette. It was interfaced to a GO pylon which triggered the 10-liter bottles in the 23 remaining slots; data gathering was not interrupted by the bottle triggers. Sensor data was digitally compensated for the effects of the electronics temperature which was monitored at all times. Additional sensors were a load cell giving the wire stress at the Rosette and two thermistor temperature sensors logged every half second. Pressure The Paros pressure sensor model 410K-101, Serial No. 50395 was calibrated on May 1, 1994 against a factory calibrated reference Paros pressure sensor. The correction was -1 +/-1 dbar for the entire range with no hysteresis. No correction was applied. Temperature Temperature calibrations are referenced to the triple point of water(.01 C) and the triple point of phenoxybenzene (26.868 C, IPTS-68, National Physical Laboratory, UK). Interpolation was done by a set of six reference thermistors calibrated at the National Research Council of Canada’s temperature standards lab. The thermistors were offset to match their calibrations at the triple point of water. Slope changes to match the high temperature triple point amounted to a change of -.0019 C at 30 C, the highest temperature measured. (Note: all WOCE data is converted to ITS-90) The main temperature sensor is a copper resistance thermometer, SN 51429. Through three years of use this sensor has been stable +/-.0065°C with no slope correction necessary. It was calibrated in May, 1994 giving an offset of -.005C and in Jan., 1995 giving an offset of -.0065°C. Calibration shifts were tracked by two complementary calibration thermistors using a separate housing, interfacing and digitizing circuitry and scanned every half second. These sensors are slower than the main sensor and were corrected for a 3 second time constant. Data from low gradient regions, deeper than 2000 m, were used to track any calibration shifts which occurred during the cruise. Because of factory changes in the internal circuitry done between the pre-cruise calibration and the start of the cruise, the post-cruise calibration was used and changes to the main temperature sensor were back-tracked using the calibration thermistors. Six digital SIS reversing thermometers were used on the rosette as an additional check. Of these, one failed to track the other sensors and others showed a tendency to drift to lower temperature. Three, #451, #647 and #679 were chosen by their consistency with each other and the reference thermistors and the fact that they were used in low gradient regions below 2000 m where time constant problems were minimal. Calibrations on the reversing thermometers were done in March ‘94. Temperature Corrections Using the post-cruise calibration, new corrections for internal electronics temperature were computed for temperature(Tmain), conductivity and the two reference thermistors (th1 and th2). Calibration constants were determined as follows and used to re-process the data: Table 5: Calibration Coefficients ------------------------------------------------------------- CONDUCTIVITY CORRECTION FACTORS FOR P AND T g#(0) = -.0000032 g#(1) = .0000001 TEMPERATURE U(0) = -5.91775 - .0065 U(1) = 7.7834E-05 / 2 U(2) = 1.92916E-13 / 4 CONDUCTIVITY V(0) = -.000519# V(1) = 1.69181E-06 V(2) = 0 cELLK = 1! ‘CELL CONSTANT TO BE ADJUSTED FOR BOTTLE SALINITIES Nref = rawdata&(13) - 3956 ‘Nref IS PROPORTIONAL TO ELECTRONICS TEMP. Nc& = rawdata&(0) + Nref * (-.472) Conductivity Nt& = rawdata&(1) + Nref * 1.24 Temperature TEMPERATURE = calctemp(U(0), U(1), U(2), Nt&) conductivity = calccond(V(0),V(1),V(2),Nc&)*(1+g#(0)*TEMPERATURE+ g#(1)*PRESSURE) * cELLK therm1raw = rawdata&(8) + (-.0545) * TREF therm2raw = rawdata&(9) + (-.04) * TREF 'calculate thermistor resistance(ohms) according to post P15n cal. rt1 = 3591.57 - 6.540890000000001D-02 * therm1raw rt2 = 3628.768 - .0766183# * therm2raw th1 = thermtemp(.00101711365#, .000294395858#, .00000015683113#, rt1, th1off) th2 = thermtemp(.00104554083#, .000290301739#, .00000015888418#, rt2, th2off) '3 sec. slower thermistors. So with a +ve rate of change, they read colder. thermdelt = 3 * tgrad 'look back by one time const. diff. 'the thermistors are -.13 m below the Copper T sensor. IF dz > 0 THEN ZOFF = -.13 ELSE ZOFF = .13 IF ABS(dz) > .14 THEN thermdeld = -ZOFF * tgrad * dt / dz ELSE thermdeld = 0 'total correction to thermistors is: thcorr = thermdelt + thermdeld tcomp = TEMPERATURE - ((th1 + th2) / 2 + thcorr) PRINT #3, USING fprintf$; rawdata&(41); PRESSURE; TEMPERATURE; SALINITY; conductivity; th1 + thcorr; th2 + thcorr; TREF; temp; TCOMP; Frame(KK) -------------------------------------------------------------------------------- In a typical cast starting at close to 30C and ending close to 1°C, the internal temperature monitor, Nref, will change by about 350 units. Over this range, corrections are as follows: Tmain: (350*1.24*7.7e-5/2) = .016°C Cond.: (-.472*350*1.69e-6) = -.000279(-.0159 in salinity) Th1: (-.545*350*.065) = 12.3 ohms (.061 °C in temperature) Comparisons for calibration purposes were generally made in water deeper than 2000 m where changes in Nref are much smaller than 350 units, typically 30 units. Using the re-processed data, the average difference between th1 and Tmain were computed for each cast only for data below 2000 dbars. For the last 26 casts, th1 and Tmain agreed within .001C so the post cruise calibration was deemed valid for these casts. Systematic changes in the comparison through the course of the cruise were attributed to the main sensor because of its more sensitive construction. However, it was noticed that the correction was different for down and up casts by about .001°C and different by about .0049°C depending on whether or not the load cell used to monitor line stress at the Rosette was attached. These offsets were very stable and consistent. Removal of the load cell also removed the difference between down and up casts and resulted in good agreement between the CTD sensors and reversing thermometers. Although this effect has not been fully explained, tests in the shop show that there appears to be some interference between the sensors and the load cell. Work is proceeding to eliminate it but, for the purposes of this cruise, a compensating offset was applied. Although Thermistor 2 was in good agreement(+/- 0.02 C) with thermistor 1, it did not fit the calibration bath thermistors or the main sensor as well as thermistor 1. So Thermistor 1 was used to track calibration shifts during the cruise. Its temperatures were offset to compensate for the .0049 C shift on casts with the load cell, the majority of the data. The temperatures measured by the reversing thermometers were corrected according to their calibrations of March, 1994 and compared with Tmain (corrected for high and low triple points). There was a great deal of scatter in the comparisons so once again comparisons were limited to depths below 2000 m and three of the sensors were eliminated because of apparent drift problems or the depth limitation already mentioned. The remaining three (#451, #647 and #679) were in good agreement with the corrections determined by Thermistor 1 although #647 had apparently drifted by about .003C by the end of the cruise. A spot check on #647 a year later showed a change of .005C at low temperature. In general, these sensors are not as stable as they should be and some further work is being done to remove solder flux from the sensor areas. More frequent calibrations are also necessary. Conductivity The conductivity sensor is a 4-electrode Guildline Pyrex glass sensor. Conductivity data was corrected for the effects of pressure and temperature on Pyrex glass(Bennett, A. S., 1976, Conversion of in situ measurements of conductivity and salinity., D.S.R., vol. 23, pp. 157 to 165.); conductivities derived from bottle salinities were used to correct the cell constant as described below. Calibration samples were drawn from the 10-liter Niskin bottles into Pyrex bottles and analyzed within a few days on board. Bottle salinities were determined using a Guildline Portasal salinometer referenced to Batch P121 standard seawater. The internal precision of the Portasal exceeds +/-.001 C in salinity. Duplicate samples to test the precision of the procedure agreed with in .002 C. Other sources of error include sampling errors and mis-triggers and are thought to be either small or to have been corrected by visual inspection of outliers in the resulting salinity and chemical data. After determining the temperature corrections above and recomputing salinity, comparisons were made at the bottle points. Upcast and downcast salinities were compared to bottle salinities and systematic pressure-dependent trends were removed. For the downcast data, an additional correction of P*(3E-8) was added to the conductivity to account for a small pressure dependency. For the upcasts, the trend was removed with a correction of P*(-1E-8). Possible causes of this effect are errors in the compensation for internal temperature, possibly due to thermal transients which would be stronger on the downcast. In order to compare with bottles collected on the upcast, down cast salinities were interpolated to the matching upcast temperature to compensate for the vertical movement caused by internal waves during the roughly 3.4 hours of a cast. This was done by comparing temperatures in the appropriate depth range and offsetting salinity to the bottle temperature using the local TS slope estimated over a 10 dbar range. A careful processing, shown in the table below, of an example cast, #97, produced salinity agreement ±.002°C from 5826 dbar to 200 dbar. Higher errors near the surface are expected because of the instability of the water column, including the TS correlation. Table 6. Hand processing of a typical down cast removes the effect of internal waves by interpolating to the temperature at which the bottle was triggered on the up cast. Agreement between bottle salinity and CTD salinity is good from 200 dbar down. P15N Cast 97 BOTTLE Depts up cast Down Salinity data cast data Error UP P Cruise T Corr.T T(P-5) T(P+5) S(P-5) S(P+5) Sinterp Sbott Bott-Interp ----------------------------------------------------------------------------------------------------------------------- 11.56 23.0931 23.0994 23.07697 23.07167 34.59999 34.57936 34.68732 34.5555 -0.13182 49.02 16.0177 16.024 16.48648 15.08266 34.46396 34.44395 34.45737 34.3999 -0.05747 100.18 12.8362 12.8425 12.8824 12.66911 34.38542 34.36216 34.38107 34.3713 -0.00977 199.96 10.8816 10.8879 11.1023 10.90042 34.21864 34.18872 34.18687 34.1845 -0.00237 299.91 10.0152 10.0215 10.20157 10.08747 34.19784 34.1877 34.18183 34.1822 0.000369 399.98 8.6104 8.6167 8.464675 8.272387 34.08092 34.06794 34.09119 34.0905 -0.00069 601.26 5.4378 5.4441 5.278873 5.119783 34.00744 34.01951 33.99491 33.998 0.003088 799.94 4.0703 4.0766 4.089046 4.046349 34.16306 34.17121 34.16544 34.1641 -0.00134 1000.49 3.4009 3.4072 3.405389 3.37939 34.29684 34.30184 34.29649 34.294 -0.00249 1250.35 2.8679 2.8742 2.842024 2.819325 34.42956 34.43389 34.42342 34.421 -0.00242 1499.69 2.4731 2.4794 2.461347 2.439049 34.51694 34.51789 34.51618 34.5127 -0.00348 1750.54 2.1319 2.1382 2.145267 2.136668 34.56895 34.57033 34.57008 34.5699 -0.00018 1999.78 1.9248 1.9311 1.92798 1.919581 34.60301 34.60434 34.60251 34.6014 -0.00111 2250.18 1.7762 1.7825 1.77219 1.76839 34.62828 34.62888 34.62667 34.6259 -0.00077 2499.08 1.6601 1.6664 1.663897 1.661197 34.64509 34.64527 34.64493 34.6433 -0.00163 2748.77 1.5847 1.591 1.594001 1.590901 34.65649 34.65697 34.65695 34.6582 0.001246 2999.49 1.5395 1.5458 1.543304 1.542004 34.66485 34.66508 34.66443 34.6643 -0.00013 3500.81 1.4817 1.488 1.489108 1.487808 34.67585 34.67623 34.67617 34.6767 0.000525 3998.45 1.4721 1.4784 1.479308 1.478308 34.68221 34.68241 34.68239 34.6818 -0.00059 4499.44 1.4903 1.4966 1.495207 1.495507 34.68624 34.68627 34.68638 34.686 -0.00038 4999.78 1.5273 1.5336 1.532005 1.532705 34.68889 34.68897 34.68908 34.6884 -0.00068 5499.6 1.5753 1.5816 1.580302 1.581402 34.69106 34.69094 34.69092 34.691 8.35E-05 5826.5 1.6071 1.6134 1.6129 1.6115 34.6914 34.6914 34.6914 34.6911 -0.0003 ----------------------------------------------------------------------------------------- Bulk processing of the data using local TS slopes estimated over 40 dbars produced a similar improvement although not quite as much as the detailed processing of cast #97. Below is a plot of the cell constants computed from each bottle at or below 2000 dbars for the whole cruise. These cell constants were averaged for each cast in order to compensate for the small systematic and random differences between the casts. Differences from this average cell constant were computed for each bottle and are shown plotted below on the same graph. This CTD was used as a backup to the WOCE CTD and is also equipped with a Paros sensor for accurate pressure determination. It was used by itself when the weather was too rough to safely launch the Rosette so there are not many bottle samples to use for comparison. However, at Station W108, it was used in a cast to 5000 m with a set of 11 bottles from 1750 dbar to 5000 dbar. These bottles were used to determine the cell constant. In addition to the comparisons to the on-board thermistors, the temperatures were compared to the adjacent casts at stations W107 and W109 to verify the temperature calibration (see the section on temperature). Finally, the TS properties of CTD6 casts taken near the end of the cruise were compared with the set of corrected WOCE CTD temperatures and their matching bottle salinities as shown below in the section on conductivity. Table 7 The initial calibration on which these changes take effect is given below: __________________________________________________________________ *CALIBRATION $TABLE: RAW CHANNELS !Name Units Fmla Pad Coefficients !-------------------------- --------------- ---- ------ ------------ Time_stamp none 10 n/a (0 1) Temperature:Analog_Probe n/a 10 n/a (0 1) Voltage:reference n/a 0 ' ' Voltage:reference:2 n/a 0 ' ' Temperature 'DEG C (ITS68)' 10 -9 (0 1) Conductivity_ratio n/a 63 -9 (0 1) Pressure DBAR 10 -9 (-10 1) Temperature:thermistor1 n/a 34 -9 (4722.61 0.203168 0.1051772E-02 0.2894819E-03 0.155711E-06 0) Temperature:thermistor2 n/a 34 -9 (4826.07 0.2058 0.1027592E-02 0.2916148E-03 0.1542955E-06 0) Temperature:digiquartz n/a 10 -9 (0 1) Temperature:2 n/a 0 -9 Transmissivity n/a 0 -9 Conductivity_ratio:2 n/a 0 -9 $END __________________________________________________________________________________________________ Pressure Pressure The Paros pressure sensor model 410K-101, Serial No. 50500 was calibrated before the cruise on Aug. 26, 1994. At 22°C, the pressure correction was -3 dbar and at 3 C, the pressure correction was 0 dbar. There was no hysteresis. No correction was applied beyond the -10 dbar correction from absolute to gauge pressure. Temperature The main temperature sensor is a copper resistance thermometer. It is complemented by two calibration thermistors in a separate housing using separate interfacing circuitry. These sensors are slower than the main sensor and serve to track any calibration shifts which may occur during the cruise. CTD6 agreed well with its second thermistor +/-.002°C but not with the first which read .01C high. Thermistor 2 indicated an average correction of -.002 C. Below is the temperature comparison at Stn. 108 which shows good agreement with the WOCE CTD values at adjacent stations (these were later corrected up by .001 C). At depths near 4000 dbar, the CTD6 temperatures seem to be a bit too high. Application of the above correction of -.002 C would bring the three casts into good agreement. Therefore, CTD6 temperatures were corrected by -.002 C. CTD6 was used near the end of the cruise without the benefit of bottle salinities. Comparison with bottles collected on other casts done with the WOCE CTD. The effect of applying the cell constant of .99984 results in good agreement in TS space between the two data sources. Ocean Physics CTD (OP CTD) This CTD was used mainly for casts with the 12-bottle Rosette to depths not exceeding 1500 dbar. Its main function was to provide temperature and pressure data for the bottles since each station was covered by full depth profile by one of the other CTD’s. Comparisons in the upper 1500 m of the water column with the other CTD’s showed a great deal of scatter due to water column variability so a lowered accuracy is claimed for this data. The calibration originally used was: Table 8: More Calibration coefficients _____________________________________________________________________________ *CALIBRATION $TABLE: RAW CHANNELS ! Name Units Fmla Pad Coefficients ! -------------------- --------------- ---- ------ ------------ Pressure DBAR 10 -99 (0 3000) Temperature 'DEG C (ITS68)' 10 -99 (0.47653E-01 0.99872) Conductivity_Ratio n/a 10 -99 (0.62E-03 0.99898) $END _______________________________________________________________________________ Pressure The pressure sensor was calibrated before the cruise and during the cruise with a reversing pressure sensor. Of 25 calibrations, the average offset determined by the reversing pressure sensor was -4.6 dbar with a standard deviation of 2.1 dbar. The pressures for this CTD were therefore offset by -4.6 dbar. Temperature The main temperature sensor is a copper resistance thermometer. Comparison with reversing thermometer #679 and #647 gave a mean correction of .0076C. The scatter on temperature comparisons as a result of water column variability suggests an accuracy of .007 for these data. Table 9. In-Situ calibrations for OP CTD ( sn 58483) REVERSING SENSORS Bottle CTD CTD Bottle Sensor Sensor Pressure Temp. Salinity Trev Prev Trev Trev-Tctd Prev-Pctd # (dbar) (°C) (psu) (°C) (dbar) (°C) (°C) (dbar) ------------------------------------------------------------------------------- 103 1002.97 2.994 34.3459 2.994 996.4 2.99924 0.00524545 -6.57 513 603.15 4.311 34.101 4.313 599 4.31847 0.00747693 -4.15 593 594.83 4.574 34.0393 4.571 593.3 4.57652 0.00252221 -1.53 671 496.05 6.363 33.9955 6.482 487 6.48785 outlier -9.05 830 603 5.363 34.0015 5.372 598.2 5.37766 0.01466279 -4.8 910 598.42 6.124 33.9983 6.109 595.3 6.11479 -0.00920787 -3.12 944 600.3 6.284 33.9929 6.31 595.6 6.31582 outlier -4.7 1001 599.02 5.899 33.9925 5.913 594.1 5.91875 0.01975773 -4.92 1058 795.6 4.201 34.1374 4.205 790.3 4.21045 0.00945798 -5.3 1115 799.5 4.31 34.1314 4.314 796.8 4.31947 0.00947711 -2.7 1172 601.88 6.306 34.0223 6.317 596.5 6.32863 0.01682863 -5.38 1229 1002.75 3.813 34.3584 3.822 997.3 3.82739 0.01439076 -5.45 1295 605.85 6.795 34.043 6.778 603.2 6.78390 -0.01109046 -2.65 2686 1000.35 4.667 34.5512 4.664 995.9 4.67579 0.00879269 -4.45 ------------------------------------------------------------------------------ averages 0.0074 -4.6 Conductivity As previously mentioned, bottle comparisons in the upper 1000 m produced noisy data. However, comparison of downcasts with corresponding up cast bottle data resulted in the following data for determining the cell constant for this CTD. The low value for the first cast, which was at Stn. P, was to some extent due to temporal variation because the upcast gave values near 1.0000. Based on these findings and accounting for the compression of the conductivity cell, the cell constant was set at 1.0001 and the accuracy of the salinity determinations was downgraded to .01, equivalent to .00025 in the cell constant. SUMMARY Processing was done according to the calibrations constants determined during the cruise. Salinity accuracy is estimated below for each CTD except in regions of the profiles where strong temperature and conductivity gradients result in errors due to sensor mismatches. Salinity spikes have been removed by hand in some profiles. Using bottle samples, on-board thermistors and reversing temperature and pressure sensors additional calibration constants were determined as follows: WOCE CTD No change to pressure. The WOCE CTD was initially calibrated with the post-cruise calibration of (offset, slope) = (-.0015, .999938). To account for changes which occurred during the cruise the temperature offsets listed in the following table were applied. Down cast salinities were matched to corresponding bottle salinities with a separate cell constant determined for each rosette cast (see table below). Agreement to a standard deviation of less than .001 in salinity with bottle samples below the 2000 dbar horizon was achieved. Temperature accuracy is estimated at .002C , salinity at .002. CTD6 No pressure correction. Temperature correction: -.002 C. Cell constant: .99984 Temperature accuracy is estimated to be .002 C and salinity accuracy to be .005. OP CTD (58483) Pressure correction: -4.6 dbar Temperature correction: .0074 C. Cell constant: 1.0002 Temperature accuracy is estimated to be .007 C and salinity accuracy to be.01 Calibration instructions for the WOCE CTD. Processing of .1ma files. The .1ma files have been edited to remove spikes, therefore, salinity cannot be recomputed from corrected temperatures and conductivities derived from the raw files. However, the conductivity has not been corrected for the pressure and temperature effects on the conductivity cell. In addition, three calibration steps are necessary to correct the data: · a pressure-dependent conductivity correction · a temperature offset and slope · a cell constant to produce agreement with bottle salinities. Since corrections are to be applied to the conductivity, it is easiest to generate a new conductivity using the despiked salinity and the SAL78 routine. The other alternative is to compute a salinity correction but because of the interaction of the temperature and conductivity corrections, this would be much harder and may lead to errors. The conductivity cell correction can be combined with the pressure-dependent conductivity correction: Rcorr = R1ma(1 + P*(1.3E-7) + T*(-3.2E-6)) The temperature offset should be applied in two steps: 1. add .004C to all WOCE CTD casts after 94030219.1ma to remove the old change in offset. This amounts to resetting the A0 in the temperature polynomial to -5.92425 for all casts. 2. add the temperature offset in the list supplied to each cast and apply slope of .999938 to all temperatures to compensate for high temperature triple point correction on the bath thermistors. The offset correction was included in the A0 figure quoted above. Apply the cell constant in the supplied list to the conductivity. Rfinal = Rcorr * Cellk Recompute salinity using the the final values of R, T and P. Table 10. WOCE CTD Corrections Relative to the post-cruise consec# celk_avg Temp offset ----------------------------------- 1 0.999874 0.008967 2 0.999874 0.008967 3 1.000084 0.008967 4 1.000084 0.008967 5 0.999975 0.008967 6 0.999975 0.008967 7 0.999952 0.007873 8 0.999952 0.008565 9 0.999952 0.007528 10 0.999952 0.007528 11 0.999952 0.007528 12 0.999952 0.007528 13 0.999952 0.007528 14 0.99998 0.007528 15 0.99998 0.008247 16 0.99998 0.007452 17 0.99998 0.007452 18 0.99998 0.007452 19 0.99998 0.007452 20 0.99998 0.007452 21 0.99998 0.007452 22 1.000003 0.007452 23 1.000003 0.007491 24 1.000003 0.007323 25 1.000003 0.007323 26 1.000003 0.007833 27 0.999915 0.006976 28 0.999915 0.008049 29 0.99996 0.006805 30 0.99996 0.008395 31 1.000006 0.00706 32 1.000006 0.008 33 1.000022 0.006856 34 1.000022 0.007994 35 1.000001 0.006858 36 1.000001 0.008517 37 0.999914 0.006794 38 0.999914 0.008112 39 1.000004 0.007239 40 1.000004 0.007831 41 0.999979 0.007011 42 0.999979 0.008248 43 0.999976 0.007022 44 0.999976 0.008251 45 0.999976 0.007333 46 0.999976 0.007333 47 0.999976 0.007333 48 0.999976 0.007333 49 0.999976 0.007333 50 0.999914 0.007333 51 0.999914 0.008126 52 0.999925 0.006856 53 0.999925 0.008557 54 0.999958 0.00672 55 1.000048 0.008258 56 1.000048 0.008069 57 1.000048 0.006733 58 1.000048 0.006733 59 1.000048 0.006733 60 1.000048 0.006733 61 0.999981 0.008607 62 0.999981 0.007265 63 1.000023 0.008451 64 1.000023 0.007009 65 1.000052 0.008704 66 1.000052 0.0085 67 1.000052 0.00729 68 1.000052 0.00729 69 1.000052 0.00729 70 1.000024 0.008214 71 1.000024 0.006935 72 1.000018 0.00845 73 1.000018 0.0067 74 1.000018 0.008257 75 1.000018 0.006689 76 1.000018 0.006689 77 1.000018 0.006689 78 0.99998 0.008199 79 0.99998 0.00683 80 0.999969 0.008258 81 0.999969 0.006682 82 0.999978 0.008042 83 0.999978 0.006981 84 1.000003 0.008231 85 1.000003 0.006532 86 1.000003 0.006532 87 1.000003 0.006532 88 0.999971 0.008156 89 0.999971 0.006674 90 0.999946 0.007911 91 0.999946 0.006303 92 0.999946 0.006303 93 0.999946 0.006303 94 0.999946 0.006303 95 0.999966 0.008344 96 0.999966 0.006289 97 0.999966 0.007755 98 0.999966 0.006223 99 0.999999 0.008071 100 0.999999 0.00636 101 0.999999 0.00636 102 0.999999 0.00636 103 0.999956 0.008208 104 0.999956 0.006075 105 0.999956 0.00797 106 0.999956 0.006163 107 0.999956 0.006163 108 0.999913 0.007599 109 0.999913 0.00592 110 0.999913 0.00592 111 0.999913 0.00592 112 0.99989 0.007439 113 0.99989 0.005707 114 0.999946 0.007031 115 0.999946 0.00535 116 0.999946 0.00535 117 0.999946 0.00535 118 0.999894 0.007352 119 0.999894 0.005468 120 0.99992 0.007035 121 0.99992 0.005618 122 0.99992 0.005618 123 0.99992 0.005618 124 0.99995 0.006594 125 0.99995 0.005225 126 0.99995 0.005225 127 0.999942 0.00733 128 0.999942 0.005769 129 0.999942 0.005769 130 0.999942 0.005769 131 0.999947 0.007092 132 0.999947 0.005238 133 0.999976 0.006334 134 0.999976 0.005268 135 0.999976 0.005268 136 0.999976 0.005268 137 0.999959 0.006557 138 0.999959 0.00538 139 0.999959 0.00538 140 0.999959 0.00538 141 0.999959 0.00538 142 0.999967 0.006914 143 0.999967 0.005579 144 0.999967 0.005579 145 0.999967 0.005579 146 0.999947 0.006437 147 0.999947 0.004717 148 0.999971 0.006279 149 0.999971 0.004864 150 0.999908 0.006209 151 0.999908 0.004681 152 0.999898 0.006197 153 0.999898 0.005034 154 0.999906 0.006135 155 0.999906 0.004743 156 0.999882 0.006066 157 0.999882 0.004782 158 0.999913 0.006024 159 0.999913 0.00525 160 0.999964 0.006435 161 0.999964 0.004984 162 0.999988 0.005913 163 0.999988 0.004589 164 0.999989 0.005864 165 0.999989 0.004678 166 0.999986 0.005753 167 0.999986 0.004637 168 0.999986 0.004637 169 0.999986 0.004637 170 0.999946 0.006031 171 0.999946 0.004525 172 0.999946 0.004525 173 0.999946 0.004525 174 0.999946 0.004525 175 0.999946 0.004525 176 0.999946 0.005627 177 0.999946 0.004717 178 0.999946 0.00577 179 0.999946 0.004102 180 0.999946 0.006606 181 0.999946 0.006542 182 0.999995 0.006774 183 0.999995 0.004974 184 0.999995 0.004974 185 0.999995 0.004974 186 0.999979 0.006897 187 0.999979 0.005886 188 0.999979 0.005886 189 0.999979 0.005886 190 0.999997 0.006928 191 0.999997 0.005113 192 0.999997 0.005113 193 0.999997 0.005113 194 0.999997 0.005113 195 0.999997 0.005113 196 0.999997 0.005113 197 0.999997 0.005113 198 0.999997 0.005113 199 0.999997 0.005113 200 0.999997 0.005113 201 0.999997 0.005113 202 0.999966 0.006938 203 0.999966 0.005147 204 0.999919 0.006827 205 0.999919 0.00519 206 0.999943 0.006884 207 0.999943 0.005562 208 0.999886 0.006935 209 0.999886 0.004688 210 0.999918 0.006777 211 0.999918 0.004838 212 0.999951 0.00643 213 0.999951 0.005236 214 0.999951 0.005236 215 0.999951 0.005236 216 0.999998 0.006688 217 0.999998 0.004688 218 0.999933 0.006314 219 0.999933 0.004831 220 0.999957 0.002581 221 0.999957 0.001114 222 0.999986 0.001947 223 0.999986 0.000596 224 0.999936 0.001738 225 0.999936 0.000237 226 0.99998 0.002004 227 0.99998 0.000515 228 0.999991 0.001325 229 0.999991 -0.00042 230 0.999956 0.00102 231 0.999956 -0.00056 232 0.999968 0.000492 233 0.999968 -0.0008 234 0.999982 0.000854 235 0.999982 -0.00054 236 0.999942 0.00079 237 0.999942 -0.00073 238 0.999926 0.000677 239 0.999926 -0.00107 240 0.999909 0.000873 241 0.999909 -0.00074 242 0.999952 0.000132 243 0.999952 -0.0008 244 0.999912 0.000461 245 0.999912 -0.00089 246 0.99993 0.000654 247 0.99993 -0.00093 248 0.99993 -0.00093 249 0.99993 -0.00093 250 0.999948 0.0005 251 0.999948 -0.00092 252 0.999915 0.001212 253 0.999915 -0.00103 254 0.999915 -0.00103 255 0.999915 -0.00103 256 0.999923 0.000493 257 0.999923 -0.00081 258 0.99991 0.000465 259 0.99991 -0.00077 260 0.99991 -0.00077 261 0.99991 -0.00077 262 0.99991 -0.00077 263 0.999938 0.001093 264 0.999938 -0.00095 265 0.999952 0.00048 266 0.999952 -0.0009 267 0.999952 -0.0009 268 0.999952 -0.0009 269 0.999944 0.000918 270 0.999944 -0.00095 271 0.999944 0.000918 272 0.999944 0.000918 273 0.999944 0.000918 274 0.999944 0.000918 275 0.999944 0.000918 276 0.999944 0.000918 277 0.999944 0.000918 278 0.999944 0.000918 279 0.999963 0.000833 280 0.999963 -0.00085 281 0.999948 0.000392 282 0.999948 -0.00138 283 0.999946 0.000633 284 0.999946 -0.0015 285 0.999945 0.000806 286 0.999945 -0.00101 287 0.999945 -0.00101 288 0.999945 -0.00101 289 0.999933 0.00081 290 0.999933 -0.0011 291 0.999962 0.000557 292 0.999962 -0.00145 293 0.999949 0.000445 294 0.999949 0.000445 295 0.999949 0.000445 296 0.999949 0.000445 297 0.999943 0.000126 298 0.999943 -0.000081 299 0.999943 -0.000081 300 0.999943 -0.000081 301 0.999917 0.000447 302 0.999917 -0.00127 303 0.999913 -0.000021 304 0.999913 -0.00112 305 0.999913 -0.00112 306 0.999913 -0.00112 307 0.999966 0.000217 308 0.999966 -0.00112 309 0.999952 0.000131 310 0.999952 -0.00171 311 0.999952 -0.00171 312 0.999952 -0.00171 313 0.99991 0.000646 314 0.99991 -0.00092 315 0.999908 0.000633 316 0.999908 -0.00132 317 0.999908 -0.00132 318 0.999908 -0.00132 319 0.999949 -0.000018 320 0.999949 -0.00085 321 0.999941 0.0000681 322 0.999941 -0.00093 323 0.999941 -0.00093 324 0.999941 -0.00093 325 0.9999 0.000256 326 0.9999 -0.00148 327 0.9999 -0.00215 328 0.999961 -0.000008 329 0.999961 -0.00101 330 0.999961 -0.00101 331 0.999961 -0.00101 332 0.999962 -0.00014 333 0.999962 -0.00139 334 0.999984 -0.000019 335 0.999984 -0.00122 336 0.999965 0.0000919 337 0.999965 -0.00116 338 0.999974 0.000235 339 0.999974 -0.00102 340 0.999984 -0.00023 341 0.999984 -0.00138 342 0.999995 0.000637 343 0.999995 -0.00122 344 0.999995 0.001024 345 0.999995 -0.00019 346 0.999995 0.001018 347 0.999995 -0.00019 348 0.999995 0.000468 349 0.999995 -0.00038 350 0.999995 0.000811 351 0.999995 -0.0004 352 0.999995 0.000455 353 0.999995 -0.00038 354 0.999942 -0.0000065 355 0.999942 -0.00047 356 0.999976 0.000123 357 0.999976 -0.00037 358 0.999958 0.000268 359 0.999958 -0.00022 360 0.99996 0.00031 361 0.99996 -0.00012 362 0.99996 -0.00019 363 0.99996 0.000261 364 0.99996 -0.0004 365 0.99996 -0.00023 366 0.99996 0.000527 367 0.99996 -0.000068 368 0.99996 -0.000068 369 0.99996 -0.00024 370 0.99996 0.00018 371 0.99996 0.00018 372 0.99996 0.00018 373 0.99996 0.000274 374 0.99996 -0.00025 375 0.99996 -0.00025 C.3. CTD The CTD probes (Models 8737 and 8705) used during this cruise are made by Guildline Instruments of Smiths Falls, Ontario, Canada. Their resolution and accuracy will be provided when data is submitted. An additional Guildline CTD with a high precision pressure sensor was used when weather would not allow rosette casts. C.3. Salinity Samples were collected in glass bottles and analyzed onboard ship using a Guildline Model 8410 Portasal. The Portasal was standardized daily with IAPSO standard sea water Batch P125. Salinity and nutrient measurements were made in an air conditioned lab (see Table 4.). C.4. Oxygen Samples were drawn through either amber rubber or Tygon tubing into 125 ml iodine flasks. The flasks were allowed to overflow twice their volume before being stoppered then unstoppered, fixed with manganous and iodide reagents according to Carpenter (1965), restoppered and shaken thoroughly. Sample temperatures were measured before initial stoppering to +/- 0.5 C. To avoid outgassing during analyses, samples were initially all refrigerated at 4 C for 1 to 24 hours before being titrated with an auto-burette (Brinkman Dosimat) to an iodine colorimetric endpoint. By station W042, samples from the mixed layer were pulling in sizable air bubbles when they were cooled. At 2 stations (W050 and W058), the effect of air contamination of pickled samples was tested and shown to add 1 to 3 umol/kg oxygen to surface samples that are cooled. This bias remains in surface layer data from stations W042 to W050, and will vary in amount depending on the amount of cooling (volume change) for each sample. Surface layer samples from W051 to W070 were not cooled. On Leg 2, flasks were sealed with tap water around the lip of the flask. This greatly reduced the amount of oxygen that enters a flask during cooling. Samples were routinely refrigerated before being analyzed. Standards were prepared as outlined in WOCE Report 73/91. C.5. Nutrients Samples were collected in 50 ml polyethylene tubes and refrigerated for a maximum of 12h (rosette) or 30 h (USW) before being analyzed. A 4 channel Technicon Analyzer measured NO3 + NO2, NO2, PO4 and dissolved Si. Analytical procedures are essentially those described by Koroleff and Grasshoff (1983). Concentrated standards were prepared from oven dried (80oC) reagents shortly before sailing on Leg 1 and again in Honolulu. Working standards were made every 1 to 2 days by diluting 1 to 6 ml of various stock solutions to 250 ml with 3.2% NaCl (w/v in double run Milli-Q water). Nitrate, nitrite and silicate standards were compared to Sagami standards. The nitrate standards agreed to within 0.1 mmol/l, but the silicate concentrations differed by 2%, an unusual finding since our prepared standards usually agree very well with the stable Sagami standards. Our silicate standard was checked on a recent cruise and again compared to Sagami and it was found to be low by 2.2%. We compared our results with data from one matching station on the Cruise TT190 of the R/V Thomas Thompson in 1985 and found that below 1000 m our silicate results are comparatively low by an average of 2.2%. No corrections have been applied to our data, although in consultation with a WOCE DQE, this might be done. Nutrient lab temperatures were recorded approximately hourly during analyses and are recorded in Table 11: Nutrient Lab Temperatures Nutrient Lab Temperatures, Leg 1 Date Station Temperature (C) Date Station Temperature (C) ---------------------------------------------------------------------------- 7 Sep. JF1-P04 22.4/22.8 27 Sep. W035/36/33 22.4/22.4/23.2 8 Sep. P13 23.1/23.8/23.9 W034 24.6 Date Station Temperature Date Station Temperature 9 Sep. P14 to P18 22.5/23.9 28 Sep. W037/38/39 21.4/28.6/25 P18 22.8/24.4 29 Sep. W040/41/43 22.4/23.3/23.1 10 Sep. P19 to P35 23.3/23.4 W042 23.0 P26 23.4/24.3 30 Sep. W044/45/46 23.5/22.7/23.7 16 Sep W004 21.3/22.4/21 1 Oct. W047/48/49 22.9/23.6/23.1 19 Sep W002/3/4 23.2/23/23.4 2 Oct. W051/50 24.2/24.3 W005 23.6 3 Oct. W052/53/54 23/23.8/24 20 Sep W006/W011 23.7/23.9 W055 24 21 Sep W012/13/14 23.8/23.8/23 4 Oct. W056/58/59 24.8/24.8/24.9 W015 24.4 5 Oct. W060/61 25.2/24.8/24.9 22 Sep W016/17/18 23.5/23.5/23.7 6 Oct. W062/63/64 25.2/-/24.9 24 Sep. W025 24.4 W065 25 25 Sep. W026/27/28 22/22.5/24 7 Oct. W067/66/68 24.7/25.7/- W029 24.3 W070 25.1 26 Sep. W030/31/32 25.3/25.6/25.2 --------------------------------------------------------------------------- Nutrient lab temperatures, Leg 2: Date Station Temperature Date Station Temperature ------------------------------------------------------------------------- 18 Oct. W071/W072 25..0 29 Oct. W108/W109 25.7/25.3 19 Oct. W073/W074 25.8/25.5 30 Oct. W111/W112 25.1/24.0 20 Oct. W078/W079 23.8/24.9 31 Oct. W113/W114W115 -/-/25.0 21 Oct. W080/W081/ 24.5/24.3 1 Nov. W116/W117 26/25.3 W082/W083 25.1/24.5 W118 24.8 22 Oct. W084/W085 24.4/24.9 2 Nov. W119/W120 24.9/25.2 W086/W087 25.2/24.5 23 Oct. W088/W089 24.8/24.9 3 Nov. W123/W124 -/25.9 W090/W091 25.5/25.4 W125 26.1 24 Oct. W092/W093 25.9/26.3 4 Nov. W126/W127 22.9/23.5 25 Oct. W096/W097 23 W128/W129 -/- W098 23/23.2 26 Oct. W099/W100 25.2/25.6 5 Nov. W130/W131 23.1/24.1 W101 25.6 W132 24.1 27 Oct. W102/W103 24.7/26 7 Nov. W133/W134 -/- W104/W105 25.8/24.6 W135 24.1 28 Oct. W106/W107 25.6/26 8 Nov. W136 24.6 ----------------------------------------------------------------------- Phosphate samples were occasionally contaminated during the second half of the first leg. A nitrate reagent containing phosphoric acid was spilt on September 30 when Stations W044, W045, and W046 were analyzed. On October 1 it was noted in the nutrient log that the crew were washing the deck with soap - Stations W047, W048 and W049 were analyzed on this day. Our water demineralizing system failed during Leg 2, which forced us to use low nutrient sea water to establish a baseline during analyses, and for the preparation of standards. Each day, a sample of 3.2% NaCl in double run Milli-Q water was analyzed to assess zero concentrations. Silicate and phosphate in low nutrient wash water was typically 2 and 0.2 uM higher than the clean salt solution. Crystals developed in the nitrite line from Station 123 onwards. This data has been labelled quality 3 for nitrite. An error is introduced into nitrate data since nitrite is subtracted from the NO3 & NO2 analysis results. Consequently, nitrates have also been assessed as questionable (quality 3) although the actual offset is only 0.1 to 0.3 umol/kg. Summing nitrite and nitrate will provide correct NO3 + NO2 values. C.6. CFCs CFC-11 and CFC-12 were analyzed by the method of Bullister and Weiss (1988). Our use of an aging Hewlett-Packard GC created problems. For the first days on Line PR6, corrosion on a circuit board shut the system down. Then as we sailed from Honolulu, the GC failed completely and we had to return to pick up another that was flown to us from IOS. Stations were occasionally skipped as columns were cleaned after they saturated with CFCs. Carrier blanks, stripper blanks, and restripped samples were analyzed throughout the cruise. Syringe air samples were taken from above the bridge, the aft deck where sampling was done, and inside the lab container. Working standard tank number 63098 was used for Stns 71, 72, 73 and 74 and tank number 63100 was used for the remaining stations. (Tank 63100 values: F-11, 583.10 ppt, standard deviation 2.05, and F-12, 279.18 ppt, standard deviation 1.04. Tank 63098 values: F-11, 443.63 ppt, standard deviation 2.63 and F-12, 502.81, standard deviation 1.91). These standards were made up of outside air. The tanks were calibrated against COCCÕs lab standard tank number 63088 (F-11, 457.59 ppt, standard deviation 0.55; and F-12, 263.13 ppt standard deviation 0.76). This COCC lab standard was calibrated by John Bullister's lab in October 1993. Data reduction was carried out using an adapted Scripps program (Weiss). This program requires salinity and temperature for calculations; the former was taken from Salinometer data; and the latter was read from the sample bucket when the syringe was removed and attached to the extraction system. There were some difficulties encountered throughout the cruise that hampered obtaining optimal results: 1)A problem with the consistency of the quality of the carrier gas meant having to subtract higher than normal stripper blanks. 2)The results of stations 83 to 97 may show zero at the 300 to 400 m depth because the threshold was initially set as per the 5890 GC program. This was modified for later stations in order to have very small peaks integrated. Thus these zero values may be a factor of threshold setting rather than a complete absence of Freon. 3)During some of the earlier stations we encountered samples affected by some sort of interference. This resulted in the F-11 peak being split or at other times summed, usually in the fifty meter sample. Neither using the split value or a summed value seemed to give a reasonable result so these samples were flagged as questionable or bad. This problem was also encountered on the first leg of the cruise. The restrips of water samples demonstrated the high stripper efficiency of the Freon analysis system. Air samples were usually taken around noon. The values reported were initially calculated with the Freon analysis program. If a particular station had a stripper blank run, the program automatically subtracted this before printing the final results. If a station did not have a stripper blank, a manual blank subtraction was applied to the calculated results based on deep water values. Limit of Detection Because contamination for F-12 was variable from day to day, detection limits were estimated each day as 3 times the standard deviation of deep sample concentrations. Thus from 2 to 7 samples were used to assess LODs in the range 0.025 to 0.244 umol/kg. Any value below this limit of detection was reported as zero. Both carrier gas and bottle blanks (deep ocean samples) were consistently zero for F-11. The lowest discernible value was 0.045 umol/kg. TABLE 12: Freon levels of air (ppt): Stn Above bridge Sampling deck Lab --------------------------------------------------------------------- F-11 F-12 F-11 F-12 F-11 F-12 --------------------------------------------------------------------- 74 252.44 612.17 280.13 852.97 300.20 615.32 74 281.21 504.43 287.27 595.06 86 271.60 507.90 315.61 366.25 86 277.83 602.34 98 279.67 673.46 271.10 571.56 273.99 493.60 101 272.04 531.47 281.40 1301.14 279.87 820.70 106 249.57 528.55 258.47 673.47 264.18 1194.8 108 263.07 518.75 261.66 516.57 265.45 689.58 113 360.34 580.22 271.18 765.35 321.11 524.49 --------------------------------------------------------------------- C.7. Total CO2 The coulometric procedure outlined in DOE (1994) was used to measure carbon dioxide in sea water. Samples were collected in 250 ml GS bottles, fixed with 200 ul of saturated HgCl2 solution, and cool stored until analyzed. C.8. Alkalinity Following the method of DOE (1994), alkalinity was determined using a temperature stable (25 C) closed titration cell, a Metrohm 665 Dosimat, a Metrohm 649 stir apparatus and an Orion model 720A pH meter. D. Acknowledgments E. References Bullister, J.L. and R.F. Weiss (1988). Determination of CCl3F and CCl2F in seawater and air. Deep-Sea Research, 35,839-853. Carpenter, J.H. 1965. The Chesapeake Bay Institute technique for the Winkler dissolved oxygen method. Limnology Oceanography 10: 141-143. DOE. 1994. Handbook of methods for analysis of the various parameters of the carbon dioxide system in sea water; version 2. A.G. Dickson and C. Goyet, eds. ORNL/CDIAC-74. Koroleff, F. and K. Grasshoff. 1983. Determination of nutrients. in Methods of Seawater Analysis. eds. K. Grasshoff, M. Ehrhardt, K. Kremling. 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. Weiss, R.F. Freon Lab Manual, Unpublished manuscript, Scripps Institute of Oceanography, San Diego, California, USA WOCE Report No. 73/91, 1991. A comparison of Methods for the Determination of Dissolved Oxygen in Seawater. WHPO Publication 91-2. F. WHPO Summary Figures 3 and 4 are not presented in this report due to CTDOXY not being available. Several data files are associated with this report. They are the 18DD9403_1.sum and 18DD9403_2.sum, 18DD9403_1.hyd and 18DD9403_2.hyd, 18DD9403_1.csl and 18DD9403_2.csl and *.wct files. The P13j.sum file contains a summary of the location, time, type of parameters sampled, and other pertinent information regarding each hydrographic station. The *.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 *wct.zip. The P13j.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 *.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 coriolis 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.