WHP CRUISE SUMMARY INFORMATION WOCE section designation A20 Expedition designation (EXPOCODE) 316N151_3 Chief Scientist(s) and their affiliation Robert Pickart, WHOI Dates 1997.07.17 - 1997.08.10 Ship KNORR Ports of call Halifax to Trinidad Number of stations 95 Geographic boundaries of the stations 43°57.94''N 56°48.62''W 50°36.98''W 06°58.13''N Floats and drifters deployed 11 Floats Moorings deployed or recovered 4 Contributing Authors none KNORR 151 LEG-III CRUISE SUMMARY: A20 Robert S. Pickart, Chief Scientist (WHOI) From 17 July - 10 August 1997 the research vessel KNORR occupied a hydrographic section extending from the Newfoundland shelf to the Suriname shelf, nominally along 52°W. This section, known as A20, is part of the Atlantic Circulation and Climate Experiment (ACCE), and one of two North Atlantic WOCE "Meridional Long- lines". The other meridional line, at 66°W, was occupied during the subsequent leg (T. Joyce, chief scientist). Thirty-one scientists representing 10 different projects participated on the cruise (Table 1). Due to wonderful weather and excellent cooperation among the different groups, we ended up occupying more stations than originally planned for a total of 95 (Figure 1). At both ends the resolution on the shelf break was 3 mi, increasing to 10-15 mi on the continental slope, and finally 40 mi in the interior (except for the Gulf Stream where the spacing was 15-25 mi). A typical deep water station included a NBIS Mark-III CTD with oxygen sensor, lowered ADCP, and 33 10-liter Niskin bottle samples. Depending on the station up to 9 different WOCE quantities were measured: CFCs, Tritium/Helium, Oxygen, PCO2, TCO2, C14, Alkalinities, Nutrients, and Salts. On selected stations (such as TTO and GEOSECS repeat stations) all of the quantities were measured; more often a subset of them was collected. Table 2 gives the position/depth of each station and indicates which tracers (including numbers of samples) were drawn. Note that Oxygen, Nutrients and Salts were collected on every station (with the exception of the shelf break crossings where limited sampling was done). In addition to the WOCE variables, Halocarbon measurements were made nominally once per day in the upper 200 m (usually from the shallowest 10 Niskin bottles, see Table 2). Underway measurements included PCO2, Halocarbons, ADCP, and thermosalinograph (which was calibrated daily using surface salinity samples). A bio-optical cast was made once per day using a self contained winch and CTD package. This was done during the CTD cast falling closest to the noon hour. Eleven ALACE floats were launched in the Sargasso Sea, corresponding to CTD sites. BRIEF NARRATIVE After occupying a test station in 3000 m of water near 57°W, we steamed to the 1000 m isobath along the northern dog-leg (Figure 1) and commenced dropping XBTs onto the shelf. This enabled us to identify the configuration of the Labrador Current prior to the CTD work (allowing us to optimally place the shelf break stations). This turned out to be quite useful as the Labrador Current contained an anomalous, large intrusion of warm water (Figure 2). For the shelf break work we used a 24-position 3.3-liter frame with a separate Mark-III, and collected water samples only within the core of the Labrador Current. At the 1000 m isobath we switched to the larger 36-position 10-liter package, which included the lowered ADCP. Water samples were taken according to the scheme described above. The dogleg portion of the section nicely sampled the slope water, including the Labrador Current, slope water front/jet, Labrador Sea Water, and Deep Western Boundary Current (DWBC, Figure 3). It should be noted that there were four current meter moorings located along the dogleg as part of a separate experiment. A Gulf Stream warm core ring was located near the seaward edge of the dogleg, and we seem to have crossed through the center of it. Shortly after this we encountered the Gulf Stream front. XBTs were used to identify the precise position of the north wall, and CTDs were subsequently placed in order to properly resolve the current. Interestingly the Gulf Stream was a factor of two narrower than normal at this longitude (only 80-90 km wide). Upon reaching the Sargasso Sea we began the 40 mi spacing, which was maintained until the southern boundary. After crossing the Corner Seamounts (near 35°N) we skirted along the outer flank of the Mid-Atlantic Ridge until roughly 15°N (Figure 1). During this part of the survey we consistently steamed at 12-13 knots. This enabled us to make up time lost on the northern boundary (due to fog near the Grand Banks). Near 10°N we doglegged into the southern boundary, again sampling the boundary current system with more detailed measurements. As in the north, we changed to the small package at the 1000 m isobath (this time including the lowered ADCP) and took measurements onto the shelf across the North Brazil Current system. Our section contains some familiar and expected features, as well as some surprises and puzzles. It is the third long line occupied near this longitude, the other two being an IGY line in 1956 and a high-quality CTD section occupied in 1983 (Figure 1). A major aim of our study is to use the 1997 ACCE lines in conjunction with the past data sets to investigate ocean climate change. The A20 salinity section (Figure 4a) shows many of the major water mass/circulation features. On the northern side note the high-salinity warm core ring and Gulf Stream front. Inshore of this, within the DWBC, resides the Labrador Sea Water whose low-salinity signal extends south of the Gulf Stream and is the cause of significant freshening at mid-depths. In the bottom-most layer the Antarctic Bottom Water becomes progressively fresher toward the southern boundary. In the upper 1000 m there is a pronounced core of Antarctic Intermediate Water extending from the southern boundary. The suite of tracers measured on the cruise will provide valuable information in elucidating the water masses as well as understanding the climate signal. The oxygen section (Figure 4b) beautifully shows both the Labrador Sea Water and Norwegian-Greenland overflow water emanating from the northern boundary. Both these features appear again on the southern boundary. Note also the low oxygen of the Antarctic Bottom Water on the southern end of the section. One of the surprises revealed by the tracers concerns the spreading of the Norwegian-Greenland overflow water from the northern boundary. The deep oxygen core extends into the Sargasso Sea centered near 3700 m (Figure 4b), whereas the analogous CFC core (not shown) is displaced roughly 500 m deeper. This perhaps reflects the difference in source functions of the two tracers in that CFCs have only entered the system in the last 50 years. Another unexpected feature is the complexity of the Labrador Sea Water signal along the northern boundary. It appears that discrete density layers are being ventilated, possibly the result of inter-annual variability in the formation of this water mass. At the conclusion of the cruise the majority of the water sample data were merged into standard WOCE data files, and, aside from the post-cruise laboratory calibrations, the CTD data were nearly final. The combination of the 52°W and 66°W sections, along with the other ACCE fieldwork and previous hydrography, will provide a revealing look at the present state of the North Atlantic and its long-term variability. TABLE 1: KN151-3 CRUISE PARTICIPANTS 1. Bob Pickart WHOI CTD (Chief Scientist) 2. Marshall Swartz WHOI CTD-hardware/watchleader 3. Daniel Torres WHOI CTD-LADCP 4. Terry McKee WHOI CTD-Software 5. Bob Millard WHOI CTD-Software 6. George Tupper WHOI CTD-Hydrography 7. Dave Wellwood WHOI CTD-Hydrography 8. Shelley Ugstad WHOI CTD-watchleader 9. Mindy Hall WHOI CTD-watchstander 10. Avon Russell WHOI CTD-watchstander 11. Brian Arbic WHOI CTD-watchstander 12. Mark Davis WHOI CTD-watchstander 13. Naomi Knoble WHOI CTD-watchstander 14. Bill Smethie LDEO CFCs 15. Eugene Gorman LDEO CFCs 16. Damon Chaky LDEO CFCs 17. Linda Baker LDEO CFCs 18. Scott Birdwhistell WHOI Tritium/He 19. Peter Landry WHOI Tritium/He 20. Chris Sabine Princeton C14/Alkalinities 21. Carrie Thomas Princeton C14/Alkalinities 22. Rick Wilke BNL TCO2 23. Ken Erikson BNL TCO2 24. Angela Wilson LDEO PCO2 25. Joe Jennings OSU Nutrients 26. Barbara Sullivan OSU Nutrients 27. Bob Moore Dalhousie Halocarbons 28. Phil Morneau Dalhousie Halocarbons 29. Wayne Groszko Dalhousie Halocarbons 30. Carol Knudson LDEO Bio-optics 31. Dana Swift UW PALACE floats TABLE 2: RV KNORR KN151-3 STATION SAMPLING SUMMARY STN. LAT (N) LONG (W) DEPTH* CFC HC HE/TR OXY PCO2 TCO2 C14 ALK NUT SALT COMMENT 1 43°14.80 50°37.01 81 "Small Frame, CTD #1088" 2 43°12.23 50°38.87 85 3 43°07.54 50°43.01 95 4 43°03.13 50°46.95 112 5 43°00.56 50°48.95 156 6 42°58.09 50°50.78 306 6 5 6 6 6 6 6 6 7 42°55.80 50°52.73 673 10 10 10 10 10 8 10 9 9 8 42°53.65 50°54.26 948 14 10 13 18 18 18 18 18 18 "Switch to Large Frame, CTD #9" 9 42°49.03 50°58.16 1387 18 18 4 1 18 18 10 42°38.06 51°07.30 1990 21 20 21 21 21 16 21 21 21 Subsurface Mooring Site 11 42°24.85 51°17.95 2664 20 25 1 1 25 25 12 42°11.70 51°29.20 3257 21 10 24 30 24 30 24 30 30 30 13 42°00.41 51°38.50 3578 22 30 1 1 30 30 14 41°49.48 51°47.59 4007 24 24 30 22 30 30 30 30 Subsurface Mooring Site 15 41°34.38 51°59.00 4565 8 10 10 10 Missing All But the Bottom 6 Btls 16 41°34.50 51°59.15 4560 18 23 1 1 23 23 Repeat of Station 15 to 3100 db 17 41°20.22 52°10.62 5068 24 10 30 24 30 30 30 30 18 41°07.72 52°20.85 5145 26 24 30 1 1 30 30 Begin Dogleg South 19 40°53.03 52°21.38 5031 25 24 30 20 30 30 30 30 20 40°33.24 52°21.36 5188 20 30 1 1 30 30 21 39°53.22 52°21.54 5269 27 10 30 1 30 26 30 30 30 22 39°12.88 52°20.96 5321 30 30 1 1 30 30 23 38°49.43 52°20.05 5337 30 23 30 22 30 30 30 30 North Wall of Gulf Stream 24 38°35.95 52°20.96 5344 12 11 30 15 30 1 30 30 25 38°20.00 52°21.28 5355 30 30 24 30 30 30 30 26 37°59.92 52°21.32 5375 29 24 30 1 1 30 30 27 37°35.08 52°21.45 5429 18 30 22 30 30 30 30 Begin 40-Mile Spacing 28 36°55.16 52°20.95 5447 30 10 8 30 1 30 30 29 36°14.35 52°21.13 2763 22 30 18 30 30 30 30 Seamount 30 35°33.70 52°20.89 4997 30 24 30 20 30 27 30 30 30 ALACE 013 31 34°53.33 52°21.10 5517 30 30 1 1 30 30 32 34°12.83 52°21.10 5558 30 11 30 23 30 30 30 30 33 33°32.33 52°21.17 5565 30 8 30 15 30 30 30 30 ALACE 020 34 32°52.48 52°20.93 5632 31 33 32 1 33 33 35 32°12.32 52°20.80 5360 33 11 23 33 20 33 33 33 33 ALACE 021 36 31°32.10 52°20.89 5498 30 33 4 33 33 33 33 37 30°52.03 52°20.59 5165 31 33 15 1 1 33 33 ALACE 026 38 30°11.83 52°20.65 5676 32 8 32 22 32 32 32 32 39 29°31.93 52°21.00 5380 30 11 33 21 33 33 33 33 ALACE 016 40 28°51.98 52°20.65 5639 32 25 33 1 ? 33 33 41 28°11.81 52°20.59 5478 33 33 33 33 33 33 ALACE 023 42 27°31.57 52°20.57 5899 30 11 8 33 33 33 27 33 33 33 43 26°51.53 52°20.38 5405 33 33 1 1 1 33 33 ALACE 002 44 26°11.32 52°20.65 5909 33 23 33 ? 33 33 33 33 45 25°31.27 52°20.53 5782 29 14 33 20 33 33 33 33 ALACE 029 46 24°51.26 52°20.48 5127 33 8 33 1 1 1 33 33 47 24°11.15 52°20.53 5450 33 33 21 33 33 33 33 ALACE 003 48 23°30.80 52°20.51 5028 29 12 33 33 33 33 33 49 22°50.78 52°20.40 5090 33 24 33 1 1 33 33 ALACE 014 50 22°10.75 52°20.38 5016 33 33 22 33 33 33 28 51 21°30.64 52°20.38 4907 32 16 32 24 32 27 32 32 32 52 20°50.25 52°20.42 4391 33 13 33 1 1 33 33 ALACE 027 53 20°10.18 52°20.23 4881 33 24 33 22 33 33 33 33 54 19°30.07 52°20.36 5363 33 33 33 33 33 33 55 18°49.91 52°20.23 5137 31 12 4 33 1 1 33 33 56 18°11.02 52°20.10 4851 33 8 33 24 33 33 33 33 57 17°31.95 52°20.17 5690 33 33 11 33 33 33 33 58 16°53.08 52°20.06 4825 33 23 33 1 1 33 33 59 16°13.87 52°20.10 4987 31 12 33 33 33 33 33 60 15°34.93 52°19.97 5115 17 8 33 24 33 33 33 33 61 14°59.90 52°20.03 4521 33 33 14 33 27 33 33 33 62 14°14.96 52°20.20 5187 33 24 33 1 33 33 63 13°33.88 52°20.02 5231 29 12 33 24 33 33 33 33 64 12°52.91 52°19.97 5231 33 8 33 12 33 33 33 33 65 12°12.04 52°20.03 5068 33 33 1 1 33 33 66 11°31.12 52°19.95 5005 31 12 23 33 33 33 33 33 67 10°50.02 52°19.85 4954 24 33 24 33 33 33 33 68 10°09.10 52°19.72 4944 33 8 33 1 26 1 33 33 End 40-Mile Spacing 69 09°53.08 52°20.90 4921 4 33 24 33 33 33 33 70 09°38.28 52°21.41 4892 31 12 33 33 33 33 33 71 09°23.07 52°21.94 4836 24 24 33 13 1 1 33 33 Begin Dogleg West 72 09°11.15 52°27.80 4770 20 33 33 33 33 33 73 08°58.50 52°33.98 4686 31 33 1 1 33 33 74 08°47.05 52°39.86 4631 33 24 33 33 33 33 33 75 08°38.08 52°43.90 4737 29 11 33 4 1 2 33 33 76 08°28.87 52°49.03 3302 30 7 24 33 19 33 24 33 33 32 77 08°19.97 52°53.27 2421 25 33 1 1 1 33 33 78 08°10.93 52°57.47 1609 17 16 21 16 21 16 21 21 21 79 08°03.47 53°01.25 1285 6 18 1 1 18 18 80 07°55.93 53°04.95 1229 14 18 18 18 18 18 81 07°49.00 53°08.57 1197 6 17 1 1 17 17 82 07°41.57 53°12.11 999 14 12 13 18 18 18 8 18 18 18 83 07°36.10 53°15.00 833 18 1 1 18 18 "Switch to Small Frame, CTD #1088" 84 07°30.90 53°17.18 682 11 12 4 12 12 12 12 85 07°25.22 53°20.15 475 11 11 1 1 11 11 86 07°22.48 53°21.40 399 10 8 10 1 1 1 10 10 87 07°19.72 53°22.67 334 3 9 9 9 9 9 9 88 07°17.03 53°24.00 282 7 1 7 1 1 7 7 89 07°14.32 53°25.35 238 7 1 1 7 7 90 07°11.60 53°26.68 208 6 6 6 6 6 6 6 91 07°08.92 53°28.05 181 6 1 1 6 6 92 07°06.18 53°29.30 131 11 3 7 1 1 7 7 93 07°03.55 53°30.60 93 5 5 5 5 5 94 07°00.82 53°32.00 85 5 5 1 1 5 5 95 06°58.12 53°33.25 76 5 5 5 5 5 Total 2066 238 608 2381 788 1488 288 1468 2380 2374 Percent 15 2 4 17 6 11 2 10 17 17 14079 Samples Taken -------------------------------------------------------------------------------- A20 CTD PROCESSING and CALIBRATIONS CTD CALIBRATIONS AND AT-SEA PROCESSING: CTD 9 Cal files Station 999 was a test station and was taken using CTD 9 and cal file: kn51d999.c00 taken from cal file sent out for CTD 9: im09kn51.cal kn51d999.c00 was updated with new conductivity terms and Pressure bias by RMillard to kn51d999.c01 Differences in cal extensions: .c00 .c01 conductivity slope 0.972844e-03 .99569966E-3 bias -0.416258e-01 .22897E-1 oxygen current slope 1.310000e-004 .0015 bias 8.540000e-001 0.0000 pcor -1.177000e-005 .00015 tcor -3.900000e-003 -.03 Pressure Temperature D1 -2.9015 -290.15 For CTD 9 im09kn51.c01 -- cal used for station 8 .c02 - was created but seemingly never used for ACQuistion. Differences between .c002 and .c03 are: diff im09kn51.c02 im09kn51.c03 (< = .c02 > = .c03) Oxygen Current SENSOR S/N ; New Sensor Installed 5 Oct 93 SENSOR S/N ; New Sensor Installed July 97 LAG ; 5.0 LAG ; 8.000000e+000 970720-MS: IM09kn51.c03 file updated from *.c01 modified by Millard. .c01 used only for stn 008. Oxygen current and conductivity values were changed from previous version. Comments on cal files: .c03 > 970720-MS: IM09kn51.c03 file updated from *.c01 modified by Millard. .c01 used only for stn 008. Oxygen current and conductivity values were changed from previous version. .c04 > 970725-TKM: im09kn51.c04 file updated from *.c03 using new cals provided by Bob Millard. New conductivities from stations 14 - 18(?) and O2 cal from stations 11 - 14. .c05 > 970728-TKM: im09kn51.c05 New pressure bias applied and new Oxygen cals provided by Bob Millard based on stations 20 - 36. Conductivity cal for stations xx - xx. .c06 > 970801-TKM im09kn51.c06 New pressure bias applied and new Oxygen cals based on stations 24 - 41 Sta. CTD Cal 1-7 CTD 1088 im88kn51.cal (attached) CTD 9 im09kn51.c01 9-29 CTD 9 im09kn51.c03 30-39 CTD 9 im09kn51.c04 40-53 CTD 9 im09kn51.c05 54-83 CTD 9 im09kn51.c06 83-95 CTD 1088 im88kn51.c01 (Oxygen current params zeroed) CTD 1088 cal files: PRESSURE quadratic -.131851E-09 slope 0.107562 bias -.435024E+02 lag 0 ACQLAG 0.200 STANDARD TEMPERATURE quadratic 0.545757E-12 slope 0.496728E-03 bias -.164305E+01 lag 250.0 CONDUCTIVITY slope 0.100263E-02 bias -.108491E-01 lag 0 ACQLAG 0.100 ALPHA -6.5E-6 BETA 1.5E-8 TO 2.8 PO 3000.0 OXYGEN CURRENT; A ; 9.658398926872436D-17 B ;-1.412062274713116D-11 C ; 7.68213574439594D-07 D ;-1.834161650101719D-02 E ; 162.4567809569779 LAG ; 7.50 PCOR ; 0.00015 TCOR ;-0.036 C2 ; 0.75 TAU ; 0.0 OXYGEN TEMPERATURE; A ; 0 B ; 0.0 C ; -.198691E-08 D ; 0.871938E-03 E ; -.110374E+02 LAG ; 0 PRESSURE TEMPERATURE A ; 0 B ; 0 C ; 0 D ; -.255382E-02 E ; 0.107186E+03 LAG ; 0 ACQLAG ; 0.225 S1 ;-2.6778E-06 S2 ;-0.36463 T0 ; 1.4 D1 ; 0.218169 ******************changes to o2 cal file **************** ctd9 OXYGEN CURRENT ; D ; 0.2325E-04 E ; 0.0 LAG ; 7.50 PCOR ; 0.00015 TCOR ;-0.036 C2 ; 0.75 TAU ; 0.0 At-sea processing: For CTD 9, conductivity sensor was very stable and required little adjusting. Terry McKee processed the data and Bob Millard provided calibration. Pressure bias required some adjusting at station 40 to make instrument measure 0 for on- deck pressure and to minimize the difference between on-deck pressure for the downcast and the upcast. Shore-based Processing: Calibrations were done by R. Millard , and processing by J. Dunworth-Baker Extensive plotting and comparing led to converting the D1 term in pressure to - 400 for CTD9 CTD9 Matlab routines were developed to better fit the data in station groups. Conductivity cals were refined. Oxygen fitting programs/routines were modified to allow for 2 different cals for each station...0-1500 dbars and 1500-bottom. The two cals were feathered together over 200 dbars. Bad surface values were smoothed or eliminated. The ctd data were extracted from the matlab workspace into the woce format, using wct_wrt2. Corrected ctdsal and ctdoxy at bottle levels were also extracted from the workspace into a sea file template, and merged into the final sea file (316N151_3.sea). MATLAB FILE: kn151v3 CRUISE: 316N151/3 DATE: 17-Dec-1998 CTD9 Conductivity Calibrations STA SLOPE BIAS STA SLOPE BIAS 8 0.000996561 -0.01 47 0.000996639 -0.01 9 0.000996561 -0.01 48 0.000996639 -0.01 10 0.000996561 -0.01 49 0.000996639 -0.01 11 0.000996561 -0.01 50 0.000996639 -0.01 12 0.000996561 -0.01 51 0.000996639 -0.01 13 0.000996561 -0.01 52 0.000996639 -0.01 14 0.000996561 -0.01 53 0.000996639 -0.01 15 0.000996611 -0.01 54 0.000996639 -0.01 16 0.000996611 -0.01 55 0.000996675 -0.01 17 0.000996611 -0.01 56 0.000996668 -0.01 18 0.000996611 -0.01 57 0.000996661 -0.01 19 0.000996611 -0.01 58 0.000996654 -0.01 20 0.000996611 -0.01 59 0.000996646 -0.01 21 0.000996611 -0.01 60 0.000996639 -0.01 22 0.000996611 -0.01 61 0.000996664 -0.01 23 0.000996572 -0.01 62 0.000996664 -0.01 24 0.000996584 -0.01 63 0.000996664 -0.01 25 0.000996595 -0.01 64 0.000996664 -0.01 26 0.000996607 -0.01 65 0.000996664 -0.01 27 0.000996619 -0.01 66 0.000996664 -0.01 28 0.00099663 -0.01 67 0.000996664 -0.01 29 0.000996642 -0.01 68 0.000996664 -0.01 30 0.000996654 -0.01 69 0.000996664 -0.01 31 0.000996665 -0.01 70 0.000996664 -0.01 32 0.000996677 -0.01 71 0.000996664 -0.01 33 0.000996689 -0.01 72 0.000996664 -0.01 34 0.000996639 -0.01 73 0.000996664 -0.01 35 0.000996639 -0.01 74 0.000996664 -0.01 36 0.000996639 -0.01 75 0.000996664 -0.01 37 0.000996639 -0.01 76 0.000996664 -0.01 38 0.000996639 -0.01 77 0.000996664 -0.01 39 0.000996639 -0.01 78 0.000996664 -0.01 40 0.000996639 -0.01 79 0.000996664 -0.01 41 0.000996639 -0.01 80 0.000996664 -0.01 42 0.000996639 -0.01 81 0.000996664 -0.01 43 0.000996639 -0.01 82 0.000996664 -0.01 44 0.000996639 -0.01 45 0.000996639 -0.01 46 0.000996639 -0.01 MATLAB FILE: kn51v5 CRUISE: 316N151/3 DATE: 21-Dec-1998 Shallow OXYGEN calibrations STA BIAS SLOPE PCOR TCOR WT LAG 8 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 9 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 10 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 11 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 12 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 13 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 14 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 15 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 16 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 17 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 18 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 19 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 20 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 21 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 22 0.04014 0.00139344 0.000148981 -0.03203 0.4331 3.7445 23 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 24 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 25 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 26 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 27 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 28 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 29 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 30 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 31 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 32 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 33 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 34 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 35 0.01354 0.00133207 0.000198752 -0.02617 0.5241 3.7445 36 0.10237 0.00127476 0.000134255 -0.02508 0.7139 3.7445 37 0.10237 0.00127476 0.000134255 -0.02508 0.7139 3.7445 38 0.10237 0.00127476 0.000134255 -0.02508 0.7139 3.7445 39 0.10237 0.00127476 0.000134255 -0.02508 0.7139 3.7445 40 0.10237 0.00127476 0.000134255 -0.02508 0.7139 3.7445 41 0.10237 0.00127476 0.000134255 -0.02508 0.7139 3.7445 42 0.10237 0.00127476 0.000134255 -0.02508 0.7139 3.7445 43 0.08834 0.00104998 0.000239343 -0.01718 0.9557 3.7445 44 0.08834 0.00104998 0.000239343 -0.01718 0.9557 3.7445 45 0.08834 0.00104998 0.000239343 -0.01718 0.9557 3.7445 46 0.08834 0.00104998 0.000239343 -0.01718 0.9557 3.7445 47 0.08834 0.00104998 0.000239343 -0.01718 0.9557 3.7445 48 0.08834 0.00104998 0.000239343 -0.01718 0.9557 3.7445 49 0.08834 0.00104998 0.000239343 -0.01718 0.9557 3.7445 50 0.07287 0.000999973 0.000270196 -0.01557 0.8203 3.7445 51 0.07287 0.000999973 0.000270196 -0.01557 0.8203 3.7445 52 0.07287 0.000999973 0.000270196 -0.01557 0.8203 3.7445 53 0.07287 0.000999973 0.000270196 -0.01557 0.8203 3.7445 54 0.07287 0.000999973 0.000270196 -0.01557 0.8203 3.7445 55 0.07287 0.000999973 0.000270196 -0.01557 0.8203 3.7445 56 0.07287 0.000999973 0.000270196 -0.01557 0.8203 3.7445 57 0.07287 0.000999973 0.000270196 -0.01557 0.8203 3.7445 58 0.07287 0.000999973 0.000270196 -0.01557 0.8203 3.7445 59 0.07287 0.000999973 0.000270196 -0.01557 0.8203 3.7445 60 0.09969 0.000772958 0.000351996 -0.00832 1.0417 3.7445 61 0.09969 0.000772958 0.000351996 -0.00832 1.0417 3.7445 62 0.09969 0.000772958 0.000351996 -0.00832 1.0417 3.7445 63 0.09969 0.000772958 0.000351996 -0.00832 1.0417 3.7445 64 0.09969 0.000772958 0.000351996 -0.00832 1.0417 3.7445 65 0.09969 0.000772958 0.000351996 -0.00832 1.0417 3.7445 66 0.09969 0.000772958 0.000351996 -0.00832 1.0417 3.7445 67 0.09969 0.000772958 0.000351996 -0.00832 1.0417 3.7445 68 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 69 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 70 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 71 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 72 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 73 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 74 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 75 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 76 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 77 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 78 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 79 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 80 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 81 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 82 0.0374 0.00141479 0.000130707 -0.02767 0.6427 3.7445 Deep Cals... STA BIAS SLOPE PCOR TCOR WT LAG 8 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 9 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 10 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 11 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 12 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 13 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 14 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 15 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 16 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 17 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 18 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 19 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 20 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 21 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 22 0.85511 0.000391626 -1.51141e-005 -0.04796 0.2813 3.7445 23 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 24 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 25 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 26 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 27 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 28 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 29 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 30 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 31 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 32 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 33 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 34 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 35 0.05047 0.00156142 0.000127505 -0.0496 0.2164 3.7445 36 0.02659 0.00158339 0.00013476 -0.05036 0.1415 3.7445 37 0.02659 0.00158339 0.00013476 -0.05036 0.1415 3.7445 38 0.02659 0.00158339 0.00013476 -0.05036 0.1415 3.7445 39 0.02659 0.00158339 0.00013476 -0.05036 0.1415 3.7445 40 0.02659 0.00158339 0.00013476 -0.05036 0.1415 3.7445 41 0.02659 0.00158339 0.00013476 -0.05036 0.1415 3.7445 42 0.02659 0.00158339 0.00013476 -0.05036 0.1415 3.7445 43 -0.05262 0.00152784 0.000173455 -0.02333 1.0655 3.7445 44 -0.05262 0.00152784 0.000173455 -0.02333 1.0655 3.7445 45 -0.05262 0.00152784 0.000173455 -0.02333 1.0655 3.7445 46 -0.05262 0.00152784 0.000173455 -0.02333 1.0655 3.7445 47 -0.05262 0.00152784 0.000173455 -0.02333 1.0655 3.7445 48 -0.05262 0.00152784 0.000173455 -0.02333 1.0655 3.7445 49 -0.05262 0.00152784 0.000173455 -0.02333 1.0655 3.7445 50 -0.00274 0.00149448 0.000153066 -0.02868 0.8203 3.7445 51 -0.00274 0.00149448 0.000153066 -0.02868 0.8203 3.7445 52 -0.00274 0.00149448 0.000153066 -0.02868 0.8203 3.7445 53 -0.00274 0.00149448 0.000153066 -0.02868 0.8203 3.7445 54 -0.00274 0.00149448 0.000153066 -0.02868 0.8203 3.7445 55 -0.00274 0.00149448 0.000153066 -0.02868 0.8203 3.7445 56 -0.00274 0.00149448 0.000153066 -0.02868 0.8203 3.7445 57 -0.00274 0.00149448 0.000153066 -0.02868 0.8203 3.7445 58 -0.00274 0.00149448 0.000153066 -0.02868 0.8203 3.7445 59 -0.00274 0.00149448 0.000153066 -0.02868 0.8203 3.7445 60 0.02911 0.00149021 0.000139251 -0.03213 1.0417 3.7445 61 0.02911 0.00149021 0.000139251 -0.03213 1.0417 3.7445 62 0.02911 0.00149021 0.000139251 -0.03213 1.0417 3.7445 63 0.02911 0.00149021 0.000139251 -0.03213 1.0417 3.7445 64 0.02911 0.00149021 0.000139251 -0.03213 1.0417 3.7445 65 0.02911 0.00149021 0.000139251 -0.03213 1.0417 3.7445 66 0.02911 0.00149021 0.000139251 -0.03213 1.0417 3.7445 67 0.02911 0.00149021 0.000139251 -0.03213 1.0417 3.7445 68 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 69 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 70 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 71 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 72 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 73 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 74 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 75 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 76 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 77 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 78 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 79 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 80 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 81 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 82 0.00492 0.00149473 0.000149884 -0.03184 1.0000 3.7445 CTD88 At sea co cals were checked and considered final. The ctdoxy was deemed un- fixable. Quality flags for ctdoxy in the ctd data and in the sea file are set to 4, and the quasi-calibrated ctdoxy are reported. MATLAB FILE: kn51v88 CRUISE: 316N151/3 Conductivity Calibrations sta slope bias 1 -0.011 0.00100259 2 -0.011 0.00100259 3 -0.011 0.00100259 4 -0.011 0.00100259 5 -0.011 0.00100259 6 -0.011 0.00100259 7 -0.011 0.00100259 83 -0.011 0.00100268 84 -0.011 0.00100268 85 -0.011 0.00100268 86 -0.011 0.00100268 87 -0.011 0.00100268 88 -0.011 0.00100268 89 -0.011 0.00100268 90 -0.011 0.00100268 91 -0.011 0.00100268 92 -0.011 0.00100268 93 -0.011 0.00100268 94 -0.011 0.00100268 95 -0.011 0.00100268 -------------------------------------------------------------------------------- ACCE 52W Cruise Report Nutrient Analyses 8-Jun-98 Equipment and Techniques Dissolved nutrient analyses were performed by J.C. Jennings, Jr. and B. E. Sullivan from Dr. L. I Gordon's group at Oregon State University (OSU). The analyses were performed using a Technicon AutoAnalyzerII (AAII) which is the property of Scripps Institution of Oceanography's Oceanographic Data Facility (ODF). This AutoAnalyzer has been used throughout the ACCE Program. For this 52W leg, we substituted an Alpkem Model 303 autosampler for the ODF autosampler. A Keithley model 575 data acquisition system was used in parallel with analog stripchart recorders to acquire the absorbance data for this leg. The software used to process the nutrient data was developed at OSU. OSU provided all of the reagent and standard materials. The analytical methods are described in Gordon et al (1994). Sampling Procedures: Nutrient samples were drawn from all sampled depths on CTD/rosette casts at stations 006 to 095. High-density polyethylene (HDPE) bottles of approximately 30-mL volume were used as sample containers, and these same bottles were positioned directly in the autosampler tray. These sample bottles were routinely rinsed at least 3 times with the sample seawater before filling. Sample bottles were rinsed twice with deionized water after sample runs, and were soaked in 10% HCl every other day. The nutrient samples were drawn following those for CFCs, helium, tritium, dissolved oxygen, carbon dioxide, alkalinity and salinity. At most stations, the AAII sample run was started before sampling was completed to reduce delay and minimize possible changes in nutrient concentration due to biological processes. Calibration and Standardization: Calibration standards for the nutrient analyses were prepared from high purity preweighed crystalline standard materials. The phosphate and nitrate standard materials had been compared in the OSU laboratory with NIST Standard Reference Materials and the silicofluoride with ultra high purity SiO2 and silicon metal. The materials used were: Phosphate standard: JT Baker potassium di-hydrogen phosphate lot 39548. Nitrate standard: Mallinkrodt potassium nitrate lot VTA. Silicic acid standard: J. T. Baker sodium silicofluoride lot 21078 10A. Nitrite standard: MCB sodium nitrite lot 4205. At the beginning of the cruise, six separate high concentration standards were prepared in deionized water; two silicic acid standards, two nitrite standards, and two mixed phosphate and nitrate standards. These duplicate standards were compared before use to ensure the accuracy of their preparation. Then more dilute mixed standards containing silicic acid, nitrate and phosphate were prepared from these high concentration standards. Similar mixed standards containing nitrate, phosphate, and silicic acid were prepared in duplicate at intervals of 7 to 10 days and kept refrigerated in HDPE bottles. For almost every station, a fresh "working standard" was prepared by adding aliquots of the high concentration mixed standard and the nitrite standard to low nutrient seawater. Working standards were not used if more than six hours had elapsed after their preparation. These working standards had nutrient concentrations similar to those found in Deep and Bottom waters. The volumetric flasks and pipettors used to prepare standards were gravimetrically calibrated prior to the cruise. The Eppendorf Maxipettor adjustable pipettors used to prepare mixed standards typically have a standard deviation of less than 0.002 mL on repeated deliveries of 10-mL volumes. Corrections for the actual volumes of the flasks and pipettors were included in the preliminary data. The WOCE Operations Manual calls for nutrient concentrations to be reported in units of micromole/kg. Because the salinity information required to compute density is not usually available at the time of initial computation of the nutrient concentrations, our concentrations are always originally computed as micromole/L (uM). This unit conversion will be made using the corrected salinity data when it is available. Measurement of Precision and Bias: Short Term Precision and Bias: Throughout the cruise, replicate samples drawn in different sample bottles from the same Niskin bottle were analyzed to assess the precision of the AAII analyses. These replicate samples were analyzed both as adjacent samples (one after the other) and at both the beginning and end of sample runs to monitor deterioration in the samples or uncompensated instrumental drift We used a randomly selected subset of these replicate samples to estimate short- term (within run) precision. The average standard deviations of 26 sets of quadruplicate determinations are listed below. The deviation of the absolute values of the sample differences gives an estimate of short-term precision while the average difference with regard to sign is an estimate of uncompensated drift or bias. Nutrient Avg. Std Dev. Avg. Difference (uM) (uM) (wrt sign) Nitrate 0.043 0.014 Nitrite 0.002 0.002 Phosphate 0.003 0.002 Silicic acid 0.102 -0.070 Longer Term Precision: In an attempt to assess the longer-term, between-station precision of the nutrient data, we fitted the deep nutrient data to sigma 4 data at several adjacent stations where natural background variability appeared to be small. We believe that the magnitude of the residuals can provide an estimate of station- to-station precision. The means of the absolute values of the residuals for several multi-station curves are presented below. Sta #point Mean Silicic acid Mean Phosphate Mean Nitrate Groups used Residual (uM) Residual (uM) Residual (uM) 33&34 19 0.58 (1.16%) 0.010 (0.67%) 0.091 (0.45%) 45-47 36 0.37 (0.74%) 0.004 (0.26%) 0.054 (0.27%) 54&55 19 0.29 (0.58%) 0.005 (0.33%) 0.070 (0.35%) Only data from depths greater than 2700m were used. Station pairs 54&55 and 33&34 were selected because high concentration mixed standards used changed at these stations. Stations 45 - 47 were selected because the deep-water variability appeared to be quite small at these locations. In all cases except the silicic acid fit for stations 33&34, the mean absolute value of the residuals expressed as a percentage of the deep-water concentration is <1.0%. Nutrient Quality Control Notes: During the 52W cruise, only limited flagging of the nutrient data was performed, except for those few bottles that were obvious leakers and for bottles whose values are average of replicate samples. (The relatively few Niskin bottles with obvious problems were usually not sampled.) Nitrate values at 11 stations on the final day of sampling were flagged because of recognized problems. Unusually rapid declines in the efficiency of the Cd reduction column affected the nitrate determinations at stations occupied on 8 August 1997 despite repeated replacement of the columns. Our protocol of running calibration standards at both the start and end of each set of samples allows us to minimize the effect of linear changes in system response, but if the change in column efficiency is non-linear with time, some error will be introduced. We have carefully examined the nitrate data at the affected stations. Although we can find no clear effects on the accuracy of these data, we have flagged them as questionable because of the recognized analytical problem affecting these stations. Wherever possible, we compared replicate samples analyzed at both the beginning and end of the affected sample runs. In the worst cases (stations 082, 084, and 087) the replicate samples differ by 0.6-0.8 uM over the course of the run. (This is about 2.5% of the near bottom nitrate values.) This should provide a worst case estimate of the imprecision in these stations. Nitrate values were flagged at the following stations: 082, 084-087, and 091-095. Post cruise QC summary: All of the nutrient data has been re-examined for problems. A few typographical errors were discovered and corrected and several "questionable" values were identified and flagged. A summary of data flagging and other notes that may aid in DQE examination is given below: Stations 1 - 5 were CTD only, no bottle samples were drawn. Station 006: Odd numbered bottles sampled Station 007: Odd numbered bottles sampled. No sample from #13, ran out of water. Station 015: Only deep bottles tripped. All parameters shifted slightly relative to adjacent stations. The deepest two bottles (1 and 2) have very low silicic acid and high salinity, flagged as questionable. Station 20: Kink in profiles at bottles 6 & 7, with 6 low and 7 high. No problems found in our raw data. Station 021: Three low silicic acid values resulted from a typo (bottles 13, 14, and 15). Edited and recalculated Station 022: Many nitrite values of -0.01. There was a problem with the DIW peaks and what looks like some non-linear drift. Flagged as 3's. Station 028: High nitrite at the bottom. No obvious problem found in our raw data. Station 038: 5648m. Low phosphate due to a typo in editing. Recalculated and edited. Station 39: 1879m. Bottle 14 Slight low nutrient, high oxygen kink, no obvious problem. Station 45: 2028m, Bottle 12 High silicic acid, flagged as questionable. Station 51: 3941m. Bottle 6 High oxygen, low nut kink. Also present as a 2- bottle feature at Station 52. No problem obvious in our raw data. Station 59: 4074m, Bottle 4 Low nutrient, high oxygen kink., No obvious problem found in our raw data. Flagged nitrate, phosphate, and silicic acid as questionable. Station 60: Multiple nutrient/oxygen kinks at 4231,3251, and 2762 m. No obvious problems found Stations 67-70: Lots of variability in nutrients and oxygen around theta range from 2.5 - 3 degrees. No obvious problems found. Station 75: 26m, Bottle 32. High silicic acid in original data. Based on the low salinity/high silicic acid relationship of the Amazon outflow, we think that nutrient samples for bottles 32 and 33 were reversed and the high silicic acid belongs with the low salt. Edited accordingly. Station 76: Bottles 12 - 16 Low phosphate (ca 0.03M). May be a temporary baseline shift. Flagged as questionable. Station 77: 1485m. Phosphate shifted up with no change in nitrate or oxygen. This appeared to be a correctable baseline shift. Phosphate data for this station were edited and recalculated accordingly. Nitrate values were flagged at stations: 082, 084-087, 091-095 due to Cd column problems discussed above. REFERENCES Gordon, L. I., J. C. Jennings, Jr., A. A. Ross and J. M. Krest. 1994. A suggested protocol for continuous flow automated analysis of seawater nutrients (phosphate, nitrate, nitrite and silicic acid) in the WOCE Hydrographic Program and the Joint Global Ocean Fluxes Study. In WOCE Operations Manual, WOCE Report No. 68/91. Revision 1, 1994.