FINAL REPORT for DEPARTMENT OF ENERGY GRANT: DE-FG02-95ER62065 submitted to CARBON DIOXIDE RESEARCH DIVISION OFFICE OF HEALTH AND ENVIRONMENTAL RESEARCH U.S. DEPARTMENT OF ENERGY WASHINGTON, DC 20545 UNDERWAY pCO2 MEASUREMENTS IN SURFACE WATERS DURING THE OCEAN MARGINS PROGRAM CRUISES IN THE NORTH WESTERN ATLANTIC OCEAN by Taro Takahashi, David W. Chipman, John Goddard, and S. C. Sutherland Lamont-Doherty Earth Observatory of Columbia University Palisades, NY 10964 3 May 2001 TABLE OF CONTENTS 1. INTRODUCTION 2. SAMPLE DATA LISTING 3. MEASUREMENTS OF pCO2 IN SURFACE WATERS 3-a) The LDEO Underway System for Surface Water pCO2 Measurements 3-b) Water-air Equilibrator 3-c) Infra-red CO2 Gas Analyzer 3-d) Data Logging System 3-e) Data Reduction Procedures 4. MEASUREMENTS OF pCO2 IN THE ATMOSPHERE AND SEA-AIR pCO2 DIFFERENCE 4-a) Measurements 4-b) Data Processing 4-c) Results 4-d) Sea-air pCO2 difference 5. SALINITY MEASUREMENTS 6. REFERENCES CITED APPENDIX I - Letter of Receipt from CDIAC. FINAL REPORT for DEPARTMENT OF ENERGY GRANT DE-FG02-95ER62065 UNDERWAY pCO2 MEASUREMENTS IN SURFACE WATERS DURING THE OCEAN MARGINS PROGRAM CRUISES IN THE NORTH WESTERN ATLANTIC OCEAN Taro Takahashi, David W. Chipman, John Goddard, and S. C. Sutherland Lamont-Doherty Earth Observatory of Columbia University Palisades, NY 10964 3 May 2001 1. INTRODUCTION This report is the final technical report for the grant DE-FG02-95ER62065, and describes the methods employed and the data obtained during the Ocean Margins Program expeditions for the measurement of pCO2 in surface waters and in the overlying atmosphere in 1993, 1994, and 1996. This is a companion report to Chipman and Takahashi (1995), in which the results obtained under the grant DE-FG02-92ER61451, the predecessor of the present grant, have been summarized. The dates and number of measurements made during this project are summarized in Table 1. The operational procedures of the underway pCO2 measurement system are described in the "pCO2 Equilibrator Users Manual" prepared by the LDEO CO2 Group (1999). The methods for measurements and calibrations are described in section 3 of this report. The ships' tracks are shown in Figure 1 (in OMPreport.doc file). Table 1 - Surface Observations listed by ship, date, and number of observations. __________________________________________________________________________ Ship (LDEO Leg) Dates Julian No. of pCO2 obs. mm/dd/yy Dates in Seawater __________________________________________________________________________ R/V Gyre & Columbus Iselin (9) 05/11/93-05/16/93 131-136 1,350 R/V Oceanus (8) 04/18/94-05/01/94 108-121 3,064 R/V Oceanus (1) 02/01/96-02/16/96 032-047 3,628 R/V Endeavor (2) 03/01/96-03/21/96 061-081 4,093 R/V Oceanus (3) 05/06/96-05/17/96 127-138 2,906 R/V S. Johnson (4) 06/22/96-06/30/96 174-182 2,073 R/V S. Johnson (5) 07/11/96-07/13/96 192-194 448 R/V S. Johnson (6) 07/19/96-07/27/96 201-209 2,169 R/V Oceanus (7) 10/07/96-10/17/96 281-291 2,624 __________________________________________________________________________ Total 99 days 22,355 2. SAMPLE DATA LISTING. LDEO group has submitted to the Carbon Dioxide Information and Analysis Center (CDIAC), Oak Ridge National Laboratory, an electronic data listing for the 22,355 measurements for surface water pCO2 , and other associated data of time, date, position, sea surface temperature, salinity, and sea-air pCO2 difference. CDIAC will be responsible for archiving and distributing these data. A letter of acknowledgement from Alex Kozry of CDIAC is attached as Appendix 1 at the end of this report. In this section we have reproduced as examples the first 20 and last 10 records from each of the 9 legs Lamont-Doherty Earth Observatory of Columbia University Printed on 05/02/01 Source File = OMP_SFCR LDEO Leg No: 1 Ship: R/V Oceanus Page 1 pCO2 of air calculated from the GlobalView CO2 Database VCO2 of dry air assuming 100% relative humidity at the sea/air interface. Seawater pCO2 is reported at Sea Surface Temperature. Only the first 20 and last 10 records of each leg are printed. Julian Sea Surface Seawater Atmosphere Delta pCO2 Sta Date Date Lat Long Temp Sal pCO2 VCO2 pCO2 sw-air No. MM/DD/YYYY DD-MM.mm DDD-MM.mm Deg C PSS uatm ppm uatm uatm 1 2/ 1/1996 32.6989 41-10.98N 71- 5.46W 3.43 31.983 386.1 364.5 361.4 24.7 2 2/ 1/1996 32.7012 41-10.38N 71- 6.06W 3.38 31.996 379.1 364.5 361.4 17.7 3 2/ 1/1996 32.7035 41- 9.72N 71- 6.78W 3.37 31.982 374.0 364.5 361.4 12.6 4 2/ 1/1996 32.7058 41- 9.36N 71- 7.26W 3.43 31.956 368.7 364.5 361.4 7.4 5 2/ 1/1996 32.7081 41- 8.82N 71- 7.86W 3.42 31.950 374.8 364.5 361.4 13.4 6 2/ 1/1996 32.7105 41- 8.16N 71- 8.58W 3.39 31.957 383.0 364.5 361.4 21.6 7 2/ 1/1996 32.7128 41- 7.74N 71- 9.06W 3.43 31.981 385.1 364.5 361.4 23.8 8 2/ 1/1996 32.7151 41- 7.20N 71- 9.66W 3.44 31.984 387.8 364.5 361.4 26.4 9 2/ 1/1996 32.7238 41- 5.16N 71-11.88W 3.52 31.979 384.7 364.5 361.4 23.4 10 2/ 1/1996 32.7261 41- 4.56N 71-12.54W 3.52 31.979 391.3 364.5 361.4 30.0 11 2/ 1/1996 32.7284 41- 4.08N 71-13.08W 3.57 31.980 393.1 364.5 361.3 31.8 12 2/ 1/1996 32.7307 41- 3.54N 71-13.68W 3.61 31.974 392.2 364.5 361.3 30.9 13 2/ 1/1996 32.7330 41- 3.00N 71-14.28W 3.64 31.978 394.3 364.5 361.3 33.0 14 2/ 1/1996 32.7353 41- 2.46N 71-14.88W 3.69 31.969 396.6 364.5 361.3 35.3 15 2/ 1/1996 32.7377 41- 1.98N 71-15.42W 3.70 31.987 397.1 364.5 361.3 35.8 16 2/ 1/1996 32.7400 41- 1.32N 71-16.14W 3.75 31.989 398.5 364.5 361.3 37.2 17 2/ 1/1996 32.7487 40-59.22N 71-18.48W 3.87 32.018 388.4 364.5 362.2 26.2 18 2/ 1/1996 32.7510 40-58.86N 71-18.90W 3.93 32.020 388.3 364.5 362.2 26.1 19 2/ 1/1996 32.7533 40-58.26N 71-19.56W 3.98 32.025 388.5 364.5 362.2 26.3 20 2/ 1/1996 32.7556 40-57.60N 71-20.28W 4.00 32.031 388.1 364.5 362.2 25.9 3619 2/16/1996 47.7781 40-58.02N 70-42.78W 2.15 31.854 329.1 364.9 362.3 -33.3 3620 2/16/1996 47.7805 40-58.68N 70-43.32W 2.06 31.842 322.1 364.9 362.3 -40.3 3621 2/16/1996 47.7915 41- 2.04N 70-45.78W 1.81 31.829 306.8 364.9 362.1 -55.3 3622 2/16/1996 47.7938 41- 2.64N 70-46.26W 1.90 31.871 304.2 364.9 362.1 -57.8 3623 2/16/1996 47.7961 41- 3.36N 70-46.74W 2.05 31.884 304.3 364.9 362.0 -57.7 3624 2/16/1996 47.7984 41- 4.02N 70-47.28W 2.15 31.888 312.6 364.9 362.0 -49.4 3625 2/16/1996 47.8008 41- 4.74N 70-47.82W 2.09 31.898 318.6 364.9 362.0 -43.4 3626 2/16/1996 47.8030 41- 5.46N 70-48.30W 2.00 31.903 317.8 364.9 362.0 -44.2 3627 2/16/1996 47.8054 41- 6.06N 70-48.78W 2.00 31.915 314.0 364.9 362.0 -48.1 3628 2/16/1996 47.8077 41- 6.84N 70-49.32W 2.06 31.914 311.7 364.9 362.0 -50.3 Lamont-Doherty Earth Observatory of Columbia University Printed on 05/02/01 Source File = OMP_SFCR LDEO Leg No: 2 Ship: R/V Endeavor Page 2 pCO2 of air calculated from the GlobalView CO2 Database VCO2 of dry air assuming 100% relative humidity at the sea/air interface. Seawater pCO2 is reported at Sea Surface Temperature. Only the first 20 and last 10 records of each leg are printed. Julian Sea Surface Seawater Atmosphere Delta pCO2 Sta Date Date Lat Long Temp Sal pCO2 VCO2 pCO2 sw-air No. MM/DD/YYYY DD-MM.mm DDD-MM.mm Deg C PSS uatm ppm uatm uatm 10 3/ 1/1996 61.8019 41-18.84N 71-10.92W 1.60 500.8 365.4 363.3 137.5 11 3/ 1/1996 61.8043 41-18.42N 71-10.26W 1.57 484.7 365.4 363.3 121.4 12 3/ 1/1996 61.8067 41-18.06N 71- 9.54W 1.52 453.2 365.4 363.3 89.9 13 3/ 1/1996 61.8092 41-17.76N 71- 8.88W 1.49 455.8 365.4 363.3 92.5 14 3/ 1/1996 61.8115 41-17.40N 71- 8.22W 1.50 472.0 365.4 363.3 108.7 15 3/ 1/1996 61.8138 41-17.10N 71- 7.62W 1.48 469.1 365.4 363.3 105.8 16 3/ 1/1996 61.8161 41-16.74N 71- 6.96W 1.46 478.4 365.4 363.3 115.1 17 3/ 1/1996 61.8184 41-16.44N 71- 6.30W 1.39 490.1 365.4 363.3 126.8 23 3/ 1/1996 61.8305 41-14.52N 71- 2.52W 1.63 466.4 365.4 363.3 103.2 24 3/ 1/1996 61.8329 41-14.16N 71- 1.80W 1.70 465.5 365.4 363.3 102.2 25 3/ 1/1996 61.8353 41-13.80N 71- 1.08W 1.71 483.1 365.4 363.3 119.9 26 3/ 1/1996 61.8378 41-13.44N 71- 0.36W 1.79 469.0 365.4 363.3 105.8 27 3/ 1/1996 61.8402 41-13.08N 70-59.64W 1.75 464.0 365.4 363.3 100.7 28 3/ 1/1996 61.8426 41-12.72N 70-58.92W 1.80 483.0 365.4 363.3 119.8 29 3/ 1/1996 61.8451 41-12.36N 70-58.26W 1.80 448.1 365.4 363.3 84.8 30 3/ 1/1996 61.8475 41-12.00N 70-57.54W 1.79 431.5 365.4 363.3 68.2 36 3/ 1/1996 61.8589 41-10.32N 70-54.24W 1.90 513.6 365.4 363.2 150.4 37 3/ 1/1996 61.8614 41- 9.96N 70-53.58W 1.93 476.0 365.4 363.2 112.8 38 3/ 1/1996 61.8638 41- 9.60N 70-52.92W 1.91 453.6 365.4 363.2 90.4 39 3/ 1/1996 61.8662 41- 9.42N 70-52.08W 1.95 439.3 365.4 363.2 76.1 6717 3/21/1996 81.1283 40- 4.20N 72-15.00W 5.08 271.9 366.3 364.1 -92.2 6718 3/21/1996 81.1306 40- 4.68N 72-14.58W 5.11 274.2 366.3 364.1 -89.9 6724 3/21/1996 81.1424 40- 7.20N 72-12.60W 5.24 281.0 366.3 364.1 -83.1 6725 3/21/1996 81.1448 40- 7.68N 72-12.12W 5.22 283.0 366.3 364.1 -81.1 6726 3/21/1996 81.1472 40- 8.22N 72-11.70W 5.26 283.1 366.3 364.1 -81.0 6727 3/21/1996 81.1496 40- 8.70N 72-11.28W 5.25 283.2 366.3 364.1 -80.9 6728 3/21/1996 81.1521 40- 9.24N 72-10.86W 5.21 283.0 366.3 364.1 -81.1 6729 3/21/1996 81.1545 40- 9.78N 72-10.44W 5.14 282.6 366.3 364.1 -81.5 6730 3/21/1996 81.1569 40-10.26N 72- 9.96W 4.96 281.5 366.3 364.1 -82.6 6731 3/21/1996 81.1594 40-10.74N 72- 9.54W 4.62 281.8 366.3 364.1 -82.3 Lamont-Doherty Earth Observatory of Columbia University Printed on 05/02/01 Source File = OMP_SFCR LDEO Leg No: 3 Ship: R/V Oceanus Page 3 pCO2 of air calculated from the GlobalView CO2 Database VCO2 of dry air assuming 100% relative humidity at the sea/air interface. Seawater pCO2 is reported at Sea Surface Temperature. Only the first 20 and last 10 records of each leg are printed. Julian Sea Surface Seawater Atmosphere Delta pCO2 Sta Date Date Lat Long Temp Sal pCO2 VCO2 pCO2 sw-air No. MM/DD/YYYY DD-MM.mm DDD-MM.mm Deg C PSS uatm ppm uatm uatm 1 5/ 6/1996 127.5780 41-21.84N 70-53.58W 8.77 373.6 366.5 363.9 9.7 2 5/ 6/1996 127.5803 41-21.42N 70-54.12W 8.74 368.6 366.5 363.9 4.7 3 5/ 6/1996 127.5826 41-20.94N 70-54.72W 8.81 366.2 366.5 363.9 2.3 4 5/ 6/1996 127.5849 41-20.40N 70-55.32W 8.91 367.8 366.5 363.8 3.9 5 5/ 6/1996 127.5872 41-19.86N 70-55.92W 8.98 368.4 366.5 363.8 4.6 6 5/ 6/1996 127.5895 41-19.38N 70-56.52W 8.93 367.4 366.5 363.8 3.6 7 5/ 6/1996 127.5919 41-18.78N 70-57.12W 8.95 366.3 366.5 363.8 2.5 8 5/ 6/1996 127.5942 41-18.24N 70-57.72W 8.88 366.4 366.5 363.8 2.5 9 5/ 6/1996 127.6052 41-15.78N 71- 0.66W 9.04 372.9 366.5 363.8 9.1 10 5/ 6/1996 127.6075 41-15.30N 71- 1.32W 9.14 373.2 366.5 363.8 9.4 11 5/ 6/1996 127.6098 41-14.70N 71- 1.86W 9.16 372.8 366.5 363.8 9.1 12 5/ 6/1996 127.6121 41-14.28N 71- 2.58W 9.23 372.8 366.5 363.7 9.1 13 5/ 6/1996 127.6145 41-13.68N 71- 3.18W 9.22 373.0 366.5 363.8 9.3 14 5/ 6/1996 127.6168 41-13.14N 71- 3.78W 9.18 372.9 366.5 363.8 9.2 15 5/ 6/1996 127.6191 41-12.66N 71- 4.38W 9.13 370.0 366.5 363.8 6.3 16 5/ 6/1996 127.6214 41-11.94N 71- 4.86W 9.34 371.8 366.5 363.7 8.1 17 5/ 6/1996 127.6324 41- 9.12N 71- 7.14W 9.11 360.8 366.5 363.8 -3.0 18 5/ 6/1996 127.6348 41- 8.46N 71- 7.50W 9.14 359.2 366.5 363.8 -4.5 19 5/ 6/1996 127.6371 41- 7.86N 71- 7.98W 8.99 358.0 366.5 363.8 -5.9 20 5/ 6/1996 127.6394 41- 7.20N 71- 8.34W 8.93 356.4 366.5 363.8 -7.5 2897 5/17/1996 138.6480 41-20.46N 70-53.46W 9.92 31.465 383.6 366.2 363.3 20.3 2898 5/17/1996 138.6503 41-21.06N 70-52.98W 9.88 31.463 382.7 366.2 363.3 19.4 2899 5/17/1996 138.6614 41-24.06N 70-50.52W 9.80 31.529 393.9 366.2 363.4 30.5 2900 5/17/1996 138.6636 41-24.60N 70-49.74W 9.75 31.509 395.1 366.2 363.4 31.7 2901 5/17/1996 138.6660 41-25.02N 70-48.90W 9.76 31.362 395.3 366.2 363.4 31.9 2902 5/17/1996 138.6683 41-25.50N 70-48.06W 10.36 31.362 397.8 366.2 363.2 34.6 2903 5/17/1996 138.6706 41-25.92N 70-47.22W 10.29 31.270 407.3 366.2 363.2 44.1 2904 5/17/1996 138.6729 41-26.34N 70-46.44W 10.47 31.212 413.5 366.2 363.2 50.3 2905 5/17/1996 138.6752 41-26.76N 70-45.78W 10.47 31.057 419.0 366.2 363.2 55.9 2906 5/17/1996 138.6775 41-27.24N 70-44.94W 10.54 31.066 422.1 366.2 363.1 59.0 Lamont-Doherty Earth Observatory of Columbia University Printed on 05/02/01 Source File = OMP_SFCR LDEO Leg No: 4 Ship: R/V Seward Johnson Page 4 pCO2 of air calculated from the GlobalView CO2 Database VCO2 of dry air assuming 100% relative humidity at the sea/air interface. Seawater pCO2 is reported at Sea Surface Temperature. Only the first 20 and last 10 records of each leg are printed. Julian Sea Surface Seawater Atmosphere Delta pCO2 Sta Date Date Lat Long Temp Sal pCO2 VCO2 pCO2 sw-air No. MM/DD/YYYY DD-MM.mm DDD-MM.mm Deg C PSS uatm ppm uatm uatm 1 6/22/1996 174.5614 41-22.68N 70-51.66W 16.54 31.328 481.9 364.6 359.4 122.4 2 6/22/1996 174.5637 41-22.20N 70-52.20W 16.49 31.328 479.2 364.6 359.5 119.7 3 6/22/1996 174.5660 41-21.78N 70-52.68W 15.84 31.318 473.5 364.6 359.7 113.8 4 6/22/1996 174.5683 41-21.30N 70-53.16W 15.75 31.329 470.1 364.6 359.8 110.4 5 6/22/1996 174.5706 41-20.82N 70-53.64W 15.68 31.331 466.6 364.6 359.8 106.8 6 6/22/1996 174.5730 41-20.34N 70-54.18W 15.51 31.356 460.7 364.6 359.9 100.8 7 6/22/1996 174.5753 41-19.92N 70-54.66W 15.50 31.347 456.0 364.6 359.9 96.1 8 6/22/1996 174.5776 41-19.44N 70-55.14W 15.74 31.350 449.8 364.6 359.8 90.1 9 6/22/1996 174.5886 41-17.28N 70-57.60W 15.62 31.311 425.9 364.6 359.8 66.1 10 6/22/1996 174.5909 41-16.80N 70-58.08W 15.64 31.308 425.9 364.6 359.8 66.1 11 6/22/1996 174.5933 41-16.44N 70-58.56W 15.65 31.293 426.0 364.6 359.8 66.2 12 6/22/1996 174.5956 41-15.90N 70-59.04W 15.55 31.278 427.0 364.6 359.8 67.2 13 6/22/1996 174.5979 41-15.48N 70-59.58W 15.34 31.294 426.5 364.6 359.9 66.6 14 6/22/1996 174.6002 41-15.06N 71- 0.06W 15.26 31.302 426.8 364.6 359.9 66.9 15 6/22/1996 174.6025 41-14.64N 71- 0.48W 15.31 31.322 427.5 364.6 359.9 67.6 16 6/22/1996 174.6049 41-14.16N 71- 1.02W 15.29 31.319 428.1 364.6 359.9 68.2 17 6/22/1996 174.6159 41-12.06N 71- 3.30W 15.06 31.501 455.0 364.6 360.0 95.0 18 6/22/1996 174.6182 41-11.64N 71- 3.84W 15.05 31.492 432.1 364.6 360.0 72.1 19 6/22/1996 174.6205 41-11.16N 71- 4.32W 15.12 31.494 417.1 364.6 360.0 57.1 20 6/22/1996 174.6228 41-10.68N 71- 4.80W 15.10 31.517 408.2 364.6 360.0 48.2 2065 6/30/1996 182.4061 41-16.14N 70-57.84W 17.04 28.910 431.2 364.0 358.7 72.5 2066 6/30/1996 182.4084 41-16.68N 70-57.36W 17.03 28.786 433.0 364.0 358.7 74.3 2067 6/30/1996 182.4195 41-19.14N 70-55.32W 17.39 29.251 442.9 364.0 358.5 84.4 2068 6/30/1996 182.4218 41-19.68N 70-54.90W 17.45 28.947 443.9 364.0 358.5 85.4 2069 6/30/1996 182.4241 41-20.22N 70-54.48W 17.44 29.012 444.0 364.0 358.5 85.5 2070 6/30/1996 182.4264 41-20.76N 70-54.00W 17.42 28.748 444.3 364.0 358.5 85.8 2071 6/30/1996 182.4288 41-21.36N 70-53.52W 17.38 28.212 444.7 364.0 358.5 86.2 2072 6/30/1996 182.4311 41-21.90N 70-53.10W 17.26 29.708 444.3 364.0 358.6 85.8 2073 6/30/1996 182.4334 41-22.50N 70-52.50W 16.93 31.070 442.9 364.0 358.7 84.2 2074 6/30/1996 182.4357 41-22.98N 70-51.78W 16.86 30.734 439.1 364.0 358.7 80.4 Lamont-Doherty Earth Observatory of Columbia University Printed on 05/02/01 Source File = OMP_SFCR LDEO Leg No: 5 Ship: R/V Seward Johnson Page 5 pCO2 of air calculated from the GlobalView CO2 Database VCO2 of dry air assuming 100% relative humidity at the sea/air interface. Seawater pCO2 is reported at Sea Surface Temperature. Only the first 20 and last 10 records of each leg are printed. Julian Sea Surface Seawater Atmosphere Delta pCO2 Sta Date Date Lat Long Temp Sal pCO2 VCO2 pCO2 sw-air No. MM/DD/YYYY DD-MM.mm DDD-MM.mm Deg C PSS uatm ppm uatm uatm 6 7/11/1996 193.1047 27-32.16N 80-21.36W 22.30 525.0 363.4 355.7 169.3 7 7/11/1996 193.1070 27-32.16N 80-21.30W 22.32 522.1 363.4 355.7 166.5 8 7/11/1996 193.1181 27-32.10N 80-21.24W 22.46 522.8 363.4 355.6 167.2 9 7/11/1996 193.1204 27-32.10N 80-21.30W 22.49 525.2 363.4 355.6 169.6 10 7/11/1996 193.1227 27-32.16N 80-21.30W 22.50 526.4 363.4 355.6 170.8 11 7/11/1996 193.1250 27-32.10N 80-21.30W 22.48 527.6 363.4 355.6 172.0 12 7/11/1996 193.1274 27-32.10N 80-21.30W 22.47 528.7 363.4 355.6 173.1 13 7/11/1996 193.1297 27-32.10N 80-21.24W 22.48 529.4 363.4 355.6 173.9 14 7/11/1996 193.1320 27-32.10N 80-21.24W 22.46 530.1 363.4 355.6 174.5 15 7/11/1996 193.1343 27-32.10N 80-21.30W 22.45 530.7 363.4 355.6 175.1 16 7/11/1996 193.1454 27-32.10N 80-21.30W 22.42 532.8 363.4 355.6 177.2 17 7/11/1996 193.1477 27-32.10N 80-21.24W 22.42 532.8 363.4 355.6 177.2 18 7/11/1996 193.1500 27-32.10N 80-21.24W 22.42 533.2 363.4 355.6 177.6 19 7/11/1996 193.1523 27-32.10N 80-21.24W 22.41 533.6 363.4 355.6 178.0 20 7/11/1996 193.1546 27-32.10N 80-21.30W 22.44 534.0 363.4 355.6 178.4 21 7/11/1996 193.1569 27-32.10N 80-21.30W 22.51 534.2 363.4 355.6 178.6 22 7/11/1996 193.1592 27-32.10N 80-21.30W 22.52 534.6 363.4 355.6 179.0 23 7/11/1996 193.1615 27-32.10N 80-21.30W 22.57 534.7 363.4 355.5 179.1 24 7/11/1996 193.5724 27-27.60N 80-19.38W 23.18 546.8 363.4 355.2 191.7 25 7/11/1996 193.5747 27-27.60N 80-19.38W 23.21 546.2 363.4 355.2 191.1 448 7/13/1996 195.7444 34-32.82N 76-44.94W 25.63 445.3 363.0 353.0 92.3 449 7/13/1996 195.7467 34-33.06N 76-44.70W 25.63 446.5 363.0 353.0 93.5 450 7/13/1996 195.7577 34-34.92N 76-43.44W 25.75 452.1 363.0 352.9 99.2 451 7/13/1996 195.7600 34-35.34N 76-43.20W 25.78 453.3 363.0 352.9 100.4 452 7/13/1996 195.7623 34-35.70N 76-42.90W 25.86 455.3 363.0 352.8 102.5 453 7/13/1996 195.7647 34-36.06N 76-42.66W 25.94 457.1 363.0 352.8 104.3 454 7/13/1996 195.7669 34-36.42N 76-42.36W 25.95 458.4 363.0 352.8 105.6 455 7/13/1996 195.7693 34-36.78N 76-42.12W 26.00 459.5 363.0 352.7 106.8 456 7/13/1996 195.7715 34-37.20N 76-41.88W 26.02 460.4 363.0 352.7 107.7 457 7/13/1996 195.7739 34-37.50N 76-41.52W 26.06 462.1 363.0 352.7 109.4 Lamont-Doherty Earth Observatory of Columbia University Printed on 05/02/01 Source File = OMP_SFCR LDEO Leg No: 6 Ship: R/V Seward Johnson Page 6 pCO2 of air calculated from the GlobalView CO2 Database VCO2 of dry air assuming 100% relative humidity at the sea/air interface. Seawater pCO2 is reported at Sea Surface Temperature. Only the first 20 and last 10 records of each leg are printed. Julian Sea Surface Seawater Atmosphere Delta pCO2 Sta Date Date Lat Long Temp Sal pCO2 VCO2 pCO2 sw-air No. MM/DD/YYYY DD-MM.mm DDD-MM.mm Deg C PSS uatm ppm uatm uatm 1 7/19/1996 201.6051 35-30.12N 75-23.64W 24.65 421.0 362.9 352.2 68.8 2 7/19/1996 201.6074 35-30.18N 75-23.64W 24.67 393.3 362.9 352.2 41.0 3 7/19/1996 201.6097 35-30.06N 75-23.88W 24.68 382.3 362.9 352.2 30.1 4 7/19/1996 201.6120 35-30.06N 75-24.12W 24.61 377.2 362.9 352.2 24.9 5 7/19/1996 201.6143 35-30.06N 75-24.12W 24.60 373.6 362.9 352.2 21.4 6 7/19/1996 201.6166 35-30.12N 75-24.06W 24.52 373.4 362.9 352.2 21.2 7 7/19/1996 201.6190 35-30.12N 75-24.00W 24.60 373.5 362.9 352.2 21.3 8 7/19/1996 201.6213 35-30.12N 75-23.88W 24.62 371.9 362.9 352.2 19.6 9 7/19/1996 201.6323 35-30.12N 75-24.30W 24.44 366.5 362.9 352.2 14.3 10 7/19/1996 201.6346 35-30.12N 75-24.18W 24.44 364.0 362.9 352.2 11.7 11 7/19/1996 201.6369 35-30.00N 75-24.18W 24.48 363.2 362.9 352.2 10.9 12 7/19/1996 201.6392 35-30.06N 75-24.12W 24.48 363.4 362.9 352.2 11.1 13 7/19/1996 201.6416 35-30.06N 75-24.12W 24.46 362.3 362.9 352.2 10.0 14 7/19/1996 201.6439 35-30.18N 75-24.12W 24.48 361.5 362.9 352.2 9.2 15 7/19/1996 201.6462 35-30.18N 75-24.06W 24.48 361.1 362.9 352.2 8.9 16 7/19/1996 201.6485 35-30.12N 75-24.00W 24.52 360.8 362.9 352.2 8.6 17 7/19/1996 201.6595 35-29.82N 75-24.12W 24.39 365.7 362.9 352.2 13.5 18 7/19/1996 201.6618 35-29.70N 75-24.24W 24.34 367.7 362.9 352.2 15.5 19 7/19/1996 201.6642 35-29.70N 75-24.30W 24.31 370.0 362.9 352.2 17.7 20 7/19/1996 201.6664 35-29.64N 75-24.36W 24.28 371.3 362.9 352.2 19.0 2215 7/27/1996 209.1330 36-41.64N 75-17.94W 23.66 395.7 362.0 352.4 43.3 2216 7/27/1996 209.1353 36-41.94N 75-18.72W 23.65 393.3 362.0 352.4 40.9 2217 7/27/1996 209.1463 36-43.32N 75-22.14W 23.66 376.7 362.0 352.4 24.3 2218 7/27/1996 209.1487 36-43.56N 75-22.92W 23.68 377.5 362.0 352.4 25.1 2219 7/27/1996 209.1509 36-43.80N 75-23.64W 23.69 410.6 362.0 352.4 58.2 2220 7/27/1996 209.1533 36-44.04N 75-24.42W 23.68 424.5 362.0 352.4 72.1 2221 7/27/1996 209.1555 36-44.28N 75-25.14W 23.67 430.6 362.0 352.4 78.2 2222 7/27/1996 209.1579 36-44.46N 75-25.92W 23.68 433.8 362.0 352.4 81.4 2223 7/27/1996 209.1602 36-44.70N 75-26.58W 23.65 436.1 362.0 352.4 83.8 2224 7/27/1996 209.1625 36-44.88N 75-27.36W 23.63 442.7 362.0 352.4 90.3 Lamont-Doherty Earth Observatory of Columbia University Printed on 05/02/01 Source File = OMP_SFCR LDEO Leg No: 7 Ship: R/V Oceanus Page 7 pCO2 of air calculated from the GlobalView CO2 Database VCO2 of dry air assuming 100% relative humidity at the sea/air interface. Seawater pCO2 is reported at Sea Surface Temperature. Only the first 20 and last 10 records of each leg are printed. Julian Sea Surface Seawater Atmosphere Delta pCO2 Sta Date Date Lat Long Temp Sal pCO2 VCO2 pCO2 sw-air No. MM/DD/YYYY DD-MM.mm DDD-MM.mm Deg C PSS uatm ppm uatm uatm 1 10/ 7/1996 281.5683 41-19.86N 70-53.40W 15.67 31.013 448.4 359.2 354.5 93.9 2 10/ 7/1996 281.5706 41-19.14N 70-53.34W 15.68 31.009 405.4 359.2 354.5 50.9 3 10/ 7/1996 281.5729 41-18.42N 70-53.34W 15.70 31.011 383.8 359.2 354.5 29.3 4 10/ 7/1996 281.5753 41-17.76N 70-53.40W 15.64 31.005 376.3 359.2 354.5 21.7 5 10/ 7/1996 281.5776 41-16.98N 70-53.40W 15.50 30.999 378.0 359.2 354.6 23.4 6 10/ 7/1996 281.5799 41-16.20N 70-53.40W 15.47 30.968 370.8 359.2 354.6 16.2 7 10/ 7/1996 281.5822 41-15.54N 70-53.34W 15.47 30.955 363.0 359.2 354.6 8.4 8 10/ 7/1996 281.5845 41-14.70N 70-53.28W 15.47 30.960 362.0 359.2 354.6 7.4 9 10/ 7/1996 281.5955 41-11.34N 70-52.38W 15.37 31.003 367.3 359.2 354.6 12.7 10 10/ 7/1996 281.5978 41-10.68N 70-52.02W 15.27 31.015 382.0 359.2 354.7 27.3 11 10/ 7/1996 281.6002 41- 9.96N 70-51.66W 15.26 31.059 397.2 359.2 354.7 42.5 12 10/ 7/1996 281.6025 41- 9.24N 70-51.36W 15.10 31.055 404.7 359.2 354.7 50.0 13 10/ 7/1996 281.6048 41- 8.52N 70-50.88W 15.11 31.074 421.8 359.2 354.7 67.0 14 10/ 7/1996 281.6071 41- 7.86N 70-50.58W 14.95 31.184 431.5 359.2 354.8 76.7 15 10/ 7/1996 281.6094 41- 7.26N 70-50.22W 14.76 31.186 435.1 359.2 354.9 80.2 16 10/ 7/1996 281.6117 41- 6.54N 70-49.86W 14.77 31.189 432.1 359.2 354.9 77.3 17 10/ 7/1996 281.6228 41- 3.18N 70-48.06W 14.31 31.301 425.3 359.2 355.0 70.2 18 10/ 7/1996 281.6251 41- 2.64N 70-47.82W 14.20 31.337 426.9 359.2 355.1 71.8 19 10/ 7/1996 281.6274 41- 1.92N 70-47.46W 14.14 31.343 432.1 359.2 355.1 77.0 20 10/ 7/1996 281.6297 41- 1.26N 70-47.10W 14.06 31.341 430.0 359.2 355.1 74.8 2615 10/17/1996 291.4066 41-10.80N 70-53.04W 14.96 30.950 380.7 360.1 355.7 25.0 2616 10/17/1996 291.4089 41-11.34N 70-53.10W 14.96 30.947 382.3 360.1 355.7 26.6 2617 10/17/1996 291.4200 41-13.98N 70-53.10W 14.94 30.902 397.1 360.1 355.7 41.4 2618 10/17/1996 291.4223 41-14.70N 70-53.16W 14.97 30.920 398.1 360.1 355.7 42.4 2619 10/17/1996 291.4246 41-15.36N 70-53.16W 15.01 30.890 396.9 360.1 355.7 41.2 2620 10/17/1996 291.4269 41-16.02N 70-53.10W 14.94 30.931 394.1 360.1 355.7 38.5 2621 10/17/1996 291.4293 41-16.80N 70-53.10W 15.06 30.927 395.7 360.1 355.6 40.1 2622 10/17/1996 291.4315 41-17.40N 70-53.10W 15.08 30.902 395.7 360.1 355.6 40.1 2623 10/17/1996 291.4339 41-18.06N 70-53.10W 15.01 30.916 393.1 360.1 355.7 37.5 2624 10/17/1996 291.4362 41-18.78N 70-53.10W 15.01 30.935 394.8 360.1 355.7 39.1 Lamont-Doherty Earth Observatory of Columbia University Printed on 05/02/01 Source File = OMP_SFCR LDEO Leg No: 8 Ship: R/V Oceanus Page 8 pCO2 of air calculated from the GlobalView CO2 Database VCO2 of dry air assuming 100% relative humidity at the sea/air interface. Seawater pCO2 is reported at Sea Surface Temperature. Only the first 20 and last 10 records of each leg are printed. Julian Sea Surface Seawater Atmosphere Delta pCO2 Sta Date Date Lat Long Temp Sal pCO2 VCO2 pCO2 sw-air No. MM/DD/YYYY DD-MM.mm DDD-MM.mm Deg C PSS uatm ppm uatm uatm 1 4/18/1994 108.9391 41- 6.78N 70-21.12W 6.38 32.053 309.8 363.9 361.9 -52.1 2 4/18/1994 108.9414 41- 6.48N 70-21.06W 6.40 31.941 309.5 363.9 361.9 -52.4 3 4/18/1994 108.9437 41- 5.70N 70-21.06W 6.40 32.040 309.0 363.9 361.9 -52.9 4 4/18/1994 108.9460 41- 4.80N 70-21.06W 6.45 32.031 309.7 363.9 361.9 -52.2 5 4/18/1994 108.9483 41- 4.38N 70-21.06W 6.44 32.023 309.2 363.9 361.9 -52.7 6 4/18/1994 108.9506 41- 3.48N 70-21.00W 6.43 32.044 309.2 363.9 361.9 -52.7 7 4/18/1994 108.9603 41- 0.48N 70-21.06W 6.26 32.133 301.0 363.9 362.0 -61.0 8 4/18/1994 108.9626 40-59.58N 70-21.06W 6.10 32.269 300.4 363.9 360.9 -60.5 9 4/18/1994 108.9649 40-59.22N 70-21.06W 5.97 32.210 300.4 363.9 360.9 -60.5 10 4/18/1994 108.9672 40-58.32N 70-21.06W 5.92 32.211 303.6 363.9 360.9 -57.3 11 4/18/1994 108.9695 40-57.48N 70-21.12W 5.74 32.276 304.7 363.9 360.9 -56.2 12 4/18/1994 108.9718 40-57.24N 70-21.06W 5.58 32.189 304.8 363.9 360.9 -56.1 13 4/18/1994 108.9816 40-56.94N 70-20.94W 5.67 32.224 307.3 363.9 360.9 -53.6 14 4/18/1994 108.9839 40-56.94N 70-20.88W 5.67 32.341 306.6 363.9 360.9 -54.3 15 4/18/1994 108.9862 40-56.94N 70-21.00W 5.67 32.210 306.3 363.9 360.9 -54.6 16 4/18/1994 108.9885 40-57.00N 70-20.94W 5.66 32.222 307.0 363.9 360.9 -53.9 17 4/18/1994 108.9907 40-57.00N 70-20.88W 5.66 32.229 307.2 363.9 360.9 -53.7 18 4/18/1994 108.9930 40-57.00N 70-20.88W 5.67 32.232 307.1 363.9 360.9 -53.8 19 4/19/1994 109.0028 40-57.00N 70-20.94W 5.64 32.225 306.5 363.9 360.9 -54.4 20 4/19/1994 109.0051 40-57.06N 70-20.88W 5.61 32.229 306.3 363.9 360.9 -54.6 3055 5/ 1/1994 121.5124 41-28.80N 70-32.04W 9.03 31.319 390.6 364.0 361.4 29.3 3056 5/ 1/1994 121.5148 41-29.04N 70-33.06W 8.93 31.327 390.5 364.0 361.4 29.1 3057 5/ 1/1994 121.5171 41-29.22N 70-34.14W 8.88 31.346 389.9 364.0 361.4 28.5 3058 5/ 1/1994 121.5194 41-29.34N 70-34.68W 8.80 31.389 390.3 364.0 361.4 28.9 3059 5/ 1/1994 121.5292 41-30.12N 70-38.64W 9.40 31.179 399.9 364.0 361.3 38.7 3060 5/ 1/1994 121.5315 41-30.30N 70-39.84W 9.68 31.136 404.7 364.0 361.2 43.5 3061 5/ 1/1994 121.5338 41-30.72N 70-40.26W 10.04 31.001 411.9 364.0 361.1 50.8 3062 5/ 1/1994 121.5361 41-31.02N 70-40.26W 9.88 30.986 404.3 364.0 361.1 43.2 3063 5/ 1/1994 121.5384 41-31.38N 70-40.32W 9.60 31.060 400.0 364.0 361.2 38.8 3064 5/ 1/1994 121.5407 41-31.44N 70-40.32W 9.95 30.915 405.1 364.0 361.1 44.0 Lamont-Doherty Earth Observatory of Columbia University Printed on 05/02/01 Source File = OMP_SFCR LDEO Leg No: 9 Ship: R/V Gyre & Columbus Iselin Page 9 pCO2 of air calculated from the GlobalView CO2 Database VCO2 of dry air assuming 100% relative humidity at the sea/air interface. Seawater pCO2 is reported at Sea Surface Temperature. Only the first 20 and last 10 records of each leg are printed. Julian Sea Surface Seawater Atmosphere Delta pCO2 Sta Date Date Lat Long Temp Sal pCO2 VCO2 pCO2 sw-air No. MM/DD/YYYY DD-MM.mm DDD-MM.mm Deg C PSS uatm ppm uatm uatm 1 5/11/1993 131.4670 35-33.48N 75-21.90W 18.06 359.6 361.4 353.6 6.0 2 5/11/1993 131.4693 35-33.00N 75-22.20W 17.87 354.3 361.4 353.6 0.8 3 5/11/1993 131.4716 35-32.52N 75-22.50W 17.62 352.9 361.4 353.6 -0.7 4 5/11/1993 131.4739 35-32.04N 75-22.80W 16.96 351.0 361.4 353.6 -2.6 5 5/11/1993 131.4762 35-31.56N 75-23.16W 16.68 345.9 361.4 353.6 -7.7 6 5/11/1993 131.4785 35-31.08N 75-23.46W 16.70 340.6 361.4 353.6 -13.0 7 5/11/1993 131.4808 35-30.60N 75-23.76W 16.75 334.7 361.4 353.6 -18.9 8 5/11/1993 131.4831 35-30.24N 75-23.94W 16.77 331.6 361.4 353.6 -22.0 10 5/11/1993 131.4926 35-30.06N 75-24.12W 16.58 339.8 361.4 353.6 -13.8 11 5/11/1993 131.4949 35-30.00N 75-24.12W 16.38 346.9 361.4 353.6 -6.7 12 5/11/1993 131.4972 35-30.00N 75-24.12W 16.41 352.2 361.4 353.6 -1.4 13 5/11/1993 131.4995 35-30.00N 75-24.12W 16.43 355.8 361.4 353.6 2.2 14 5/11/1993 131.5018 35-30.00N 75-24.12W 16.46 359.0 361.4 353.6 5.4 15 5/11/1993 131.5041 35-30.00N 75-24.12W 16.51 360.2 361.4 353.6 6.6 16 5/11/1993 131.5064 35-30.00N 75-24.12W 16.46 361.0 361.4 353.6 7.4 17 5/11/1993 131.5087 35-30.00N 75-24.12W 16.48 360.7 361.4 353.6 7.1 19 5/11/1993 131.5182 35-30.00N 75-24.06W 16.48 357.9 361.4 353.6 4.4 20 5/11/1993 131.5205 35-30.00N 75-24.06W 16.48 360.7 361.4 353.6 7.1 21 5/11/1993 131.5229 35-30.06N 75-24.06W 16.52 364.1 361.4 353.6 10.5 22 5/11/1993 131.5252 35-30.06N 75-24.06W 16.46 367.5 361.4 353.6 14.0 1531 5/16/1993 136.3976 36-54.06N 75-52.38W 17.21 183.1 360.9 355.0 -172 1532 5/16/1993 136.3999 36-54.36N 75-52.92W 17.51 166.4 360.9 355.0 -189 1534 5/16/1993 136.4095 36-55.68N 75-55.20W 17.82 123.7 360.9 355.0 -231 1535 5/16/1993 136.4118 36-55.98N 75-55.74W 17.85 118.2 360.9 355.0 -237 1536 5/16/1993 136.4141 36-56.16N 75-56.16W 17.95 113.9 360.9 355.0 -241 1537 5/16/1993 136.4164 36-56.28N 75-56.52W 18.10 110.2 360.9 355.0 -245 1538 5/16/1993 136.4187 36-56.46N 75-57.12W 18.20 106.9 360.9 355.0 -248 1539 5/16/1993 136.4210 36-56.64N 75-57.78W 18.24 104.5 360.9 355.0 -250 1540 5/16/1993 136.4233 36-56.76N 75-58.44W 18.26 103.0 360.9 355.0 -252 1541 5/16/1993 136.4257 36-56.88N 75-59.04W 18.31 102.1 360.9 355.0 -253 3. MEASUREMENTS OF pCO2 IN SURFACE WATERS 3-a) The LDEO Underway System for Surface Water pCO2 Measurements: The system for underway measurements of pCO2 in surface waters consists of a) a water-air equilibrator, b) a non-dispersive infra-red CO2 gas analyzer and c) a data logging system. The measurement system is schematically shown in Fig. 1, and is similar with the one described in Bates et al. (1998). Each of these units and the data reduction procedures used will be described below. Figure 2 - The underway pCO2 system used for the measurements of pCO2 in surface waters during the Ocean Margins Program. 3-b) Water-air Equilibrator: The equilibrator has a total volume of about 30 liters and is equipped with a specially designed drain which maintains automatically the level of water in the equilibrator at a constant level at about half the height of the equilibrator leaving about 15 liters of headspace. Seawater from the ship's uncontaminated water line is continuously pumped into the equilibrator at a rate of about 10 liters/min, giving a mean residence time of water in the equilibrator of about 1.5 minutes. The headspace above the water serves as an equilibration chamber. A carrier gas (commonly marine air) is drawn into the chamber by a diaphragm pump, and exchanges CO2 with a continuous flow of seawater sprayed into the chamber through a shower head. Because of large gas-water contact areas created by fine water droplets as well as gas bubbles in the pool of water, CO2 equilibration between the carrier gas and seawater is achieved rapidly with a e-folding time of 2 to 3 minutes. Under normal operating conditions, the carrier gas in the equilibration chamber is pumped into the infra-red gas analyzer at a rate of about 50 ml/min. At this rate, the residence time of the carrier gas in the equilibration chamber is about 300 minutes, that is about 100 times as long as the equilibration time. Therefore, the carrier gas in the head space is always in equilibrium with water. The over all response time of the equilibrator system has been estimated to be of an order of several minutes. The large volume of water in the equilibrator is chosen in order to have a large thermal inertia of the equilibrator, so that the effects of room temperature changes on the equilibration temperature may be minimized. The temperature of water in the equilibrator is monitored continuously using a Guildline platinum resistance thermometer (readable to 0.05 oC) and recorded on the data logging computer. A calibrated mercury thermometer is also inserted in the equilibrator for testing the performance of the platinum thermometer. At the gas intake end of the equilibrator, a flow indicator based on U-tube manometer is attached. This gives a visual confirmation for the fact that marine air is taken into the equilibration chamber at a desired flow rate. Since we operate the system with the equilibration chamber at the same pressure as the ambient room pressure, the total pressure, at which the gas was equilibrated, is measured using a precision electronic barometer (Setra Model 270, Acton, MA) outside the equilibrator. This equilibration pressure is also logged on the computer. The temperature and salinity of seawater at the in-situ conditions were measured using a SeaBird Model SBE-21 thermosalinograph aboard Oceanus, Endeavor, and Seward Johnson. The precision of the reported temperature data has been estimated to be about 0.005 degC. 3-c) Infra-red CO2 Gas Analyzer: The equilibrated gas was passed through a water trap (to collect aerosols and condensates), mass flow controller and a reverse flow naphion dryer (PermaPure flushed with pure nitrogen gas) to remove water vapor (to a level of -20oC), and was introduced into the IR sample cell at a rate of about 50 ml/min for CO2 determinations. A LI-COR infra-red gas analyzer (Model 6251, Lincoln, NB) was used. After about 3 minutes of purging period, the gas flow was stopped and readings were recorded on the computer. Although an electronic circuit was provided by the manufacturer in order to linearize the CO2 response, it exhibited a few inflexions that deviated from linearity by a few ppm. Therefore, we chose not to use the outputs from the linearization circuit supplied by the manufacturer. Instead, we used five standard gas mixtures (one pure nitrogen and four CO2-air mixtures) during the expeditions, and established response curves using the raw output from the analyzer. The CO2 concentrations in the gas mixtures were calibrated using the SIO standards determined by C. D. Keeling's group using the manometric method. The concentrations of CO2 in the standard gas mixtures are summarized in Table 2. Table 2 - Concentrations of CO2 in the CO2-air gas mixtures using during the OMP Expeditions, 1993-1996. The values are in ppm mole fraction of CO2 in dry air, and have a precision of about + 0.1 ppm. Std. 1 is pure nitrogen gas and has a CO2 concentration of 0.00 ppm. _____________________________________________________________________ Ship/Cruise Dates CO2 concentrations (ppm) (LDEO #) ---------------------------------------- Std. 2 Std 3 Std 4 Std5 R/V Gyre & Columbus Iselin (9) 05/11/93-05/16/93 R/V Oceanus (8) 04/18/94-05/01/94 157.29 346.74 855.52 471.60 R/V Oceanus (1) 02/01/96-02/16/96 236.29 364.25 105.20 493.72 R/V Endeavor (2) 03/01/96-03/21/96 233.84 366.52 109.95 495.18 R/V Oceanus (3) 05/06/96-05/17/96 236.29 364.25 105.20 493.72 R/V S. Johnson (4) 06/22/96-06/30/96 236.29 364.25 105.20 493.72 R/V S. Johnson (5) 07/11/96-07/13/96 236.29 364.25 105.20 493.72 R/V S. Johnson (6) 07/19/96-07/27/96 236.29 364.25 105.20 493.72 R/V Oceanus (7) 10/07/96-10/17/96 236.29 364.25 105.20 493.72 _______________________________________________________________________ During normal operations, each of the standard gas mixtures was passed through the analyzer for 70 to 90 seconds at a rate of about 60 ml/min. This replaced the IR analyzer cell completely with the new gas. The flow was stopped for 5 seconds and then a millivolt reading from the analyzer was taken and recorded. Samples of equilibrated air and marine air were pumped through the analyzer for 180 seconds (3 minutes) at a rate of about 50 ml/min to purge the previous sample in the IR cell. The flow was stopped for 5 seconds and a reading for the analyzer output was recorded. This procedure was intended to eliminate errors due to fluctuations of the dynamic pressure within the IR cell by irregular gas flow rates. The slow flow rates used for samples were required for the removal of water vapor using the PermaPure membrane dryer. Between two sets of calibration runs using the five standard gases, 6 to 20 samples were analyzed depending upon the stability of the IR analyzer. 3-d) Data Logging System: The following values were recorded on a laptop computer. The sample locations were derived from a GPS positioning unit that is a part of our surface water pCO2 system. The CO2 readings for samples were recorded once every 3 minutes (180 seconds), and those for the standard gas mixtures once every 1.5 minutes. Date, Time (GMT), Latitude, Longitude, Sample ID (standard gas cylinder numbers, seawater CO2, atmospheric CO2) Barometric pressure in the laboratory (to 0.1 mb) IR cell temperature, Gas flow rate in the IR cell (to 0.1 ml/min), Temperature of equilibration (to 0.01 oC), Analyzer output (millivolts to 0.1 mv) CO2 concentration in dry gas sample (preliminary based on the last response curve), and pCO2 (preliminary value based on the last response curve). 3-e) Data Reduction Procedures: The concentration of CO2 in the sample was computed in the following way based on the millivolt reading and time of the reading. The millivolt reading taken for each of the five standard gases at the time of sample measurement was computed by linearly interpolating as a function of time using the readings taken before and after the respective standard gases were analyzed. This yields millivolt reading for each of the five standard gases at the time when the sample was analyzed. These five values were fit to a quadratic equation . This serves as the response curve. The CO2 concentration in the sample was computed using the response curve that was established at the time of each sample analysis. The method described above yields atmospheric CO2 values that are consistent with those reported for the South Pole and the Cape Grim by the Climate Monitoring and Diagnostics Laboratory/NOAA in Boulder, CO. The partial pressure of CO2 in seawater, (pCO2)sw, at the temperature of equilibration, Teq, in the unit of microatmospheres (uatm) was computed using the concentration of CO2 in dried equilibrated air (VCO2)eq in the following expression: (pCO2)sw @ Teq = (Vco2)eq x (Pb - Pw), [1] (Vco2)eq = the mole fraction concentration (ppm) of CO2 in the dried equilibrated carrier gas; Pb = the barometric pressure (that is equal to the total pressure of equilibration) in atmospheres; and Pw = the equilibrium water vapor pressure in atmospheres at Teq (oC) and salinity. The water vapor pressure was computed using the following formulation; Pw (atm) = (1/760) x (1 - 5.368 x 10^(-4) x Sal) x EXP{[0.0039476 - (1/TK)]/1.8752x10^(-4)}, [2] where Sal is salinity on the Practical Salinity Scale measured using the ship's thermosalinograph, and TK is the temperature of equilibration in deg K. The (pCO2)sw at the in-situ temperature, was computed using a constant value of 0.0423 % per oC for the effect of temperature (Takahashi et al., 1993): (pCO2)sw @ T in-situ = (pCO2)sw @ Teq x EXP[0.0423 x (Tin-situ - Teq)]. [3] The value for T in-situ is taken to be the seawater temperature measured by the ship's thermosalinograph at the time of pCO2 measurements. Teq is generally warmer than Tin-situ by 0.5 ~ 0.8 oC. Hence the temperature correction is normally less than 3% of pCO2 values. The over all precision of the reported pCO2)sw values has been estimated to be about +1.5 uatm. 4. MEASUREMENTS OF pCO2 IN THE ATMOSPHERE AND SEA-AIR pCO2 DIFFERENCE 4-a) Measurements: The air measurement system is shown schematically in Fig. 1. Uncontaminated marine air samples were collected about 10 m above the sea surface using a DEKORON tubing (1/4" i.d., Calco Inc., PA), a thin-wall aluminum tubing protected by plastic outside casing. The intake was located at the middle of the foremast about 10 m above the sea surface. A KNF Neuberger air pump that was located near the IR analyzer was used to pump air through the tubing and into the IR analyzer. Even when air samples were not analyzed, the pump was on all the time to keep the air flowing through the sampling line. For the analysis, the air sample was passed through a water trap and a drying column to remove water vapor (the same PermaPure column as used for the equilibrated gas) and introduced into the IR cell for CO2 analysis at a rate of about 50 ml/min. After 3 minutes of purging the cell, the flow was stopped for 5 seconds and the IR millivolt output reading was recorded. 4-b) Data Processing: The partial pressure of CO2 in the air, (pCO2)air, was computed in the unit of microatmospheres (uatm) in the same way as that for seawater using Eq. [4] below: (pCO2)air = (Vco2)air x (Pb - Pw), [4] (Vco2)air = the mole fraction concentration (ppm) of CO2 in the dried air sample; Pb = the barometric pressure at sea surface in atmospheres; and Pw = the equilibrium water vapor pressure in atmospheres at T in-situ (oC) and salinity given by Eq. [2]. The precision of the atmospheric pCO2 values have been estimated to be about + 1 uatm. 4-c) Results: The results of our measurements were used for internal quality control purposes only, and are not reported here. Due to the small size of the ships involved in this program, we were unable to eliminate stack-gas contamination of our intake. Furthermore, being down wind from the northeastern United States and the large industrial and vehicle CO2 emissions seems to have contributed to excessive local variations we could not eliminate. 4-d) Sea-air pCO2 difference: Since the atmospheric CO2 concentrations measured aboard the ships during the project are not representative values for the marine air over our study areas as discussed above, we have used the weekly zonal mean concentrations of atmospheric CO2 in marine boundary layer reported in the GLOBALVIEW-CO2 (2000). The pCO2 in marine air has been computed using Eq. [4], in which the following were used: (1) climatological mean barometric pressure from Atlas of Surface Marine data (1994), (2) the observed SST, (3) the observed salinity when available, or an estimated salinity of 35.0. The sea-air pCO2 difference, delta pCO2 sw-air, reported in the data table has been computed by subtracting the atmospheric pCO2 thus computed from the seawater pCO2 obtained using Eq. [3]. 5. SALINITY MEASUREMENTS: The salinity data reported here were obtained from the shipboard analytical system. Each of the five ships has a slightly different system, maintained in five different ways. Since we have not been able to verify the quality of these data, we report them as they were provided to us aboard the ship. 6. REFERENCES CITED Atlas of Surface Marine Data (1994). CD-ROM NODC-56, Ocean Climate Laboratory, NOAA, Washington, D. C.. Bates, N. R., Takahashi, T., Chipman, D. W. and Knapp, A. H. (1998). Variability of pCO2 on diel to seasonal time scales in the Sargasso Sea. Jour. Geophys. Res., 103, 15567-15585. Chipman, D.W. and T. Takahashi (1995). Determination of Ocean/Atmosphere Carbon Dioxide Flux within OMP Survey Area. Final Technical Report for Grant DE-FG02-92ER61451, Lamont-Doherty Observatory of Columbia University, 16 pp. CO2 Group, Lamont-Doherty Earth Observatory. (1999) "pCO2 Equilibrator Users Manual", LDEO of Columbia University, Palisade, NY, pp.10. GLOBALVIEW-CO2 (2000). Cooperative Atmospheric Data Integration Project - Carbon Dioxide. CD-ROM, NOAA CMDL, Boulder, Colorado [Also available on Internet via anonymous FTP to ftp.cmdl.noaa.gov, Path: ccg/co2/GLOBALVIEW], Takahashi, T., Olafsson, J., Goddard, J., Chipman, D. W. and Sutherland, S. C., (1993). Seasonal variation of CO2 and nutrients in the high-latitude surface oceans: A comparative study. Global Biogeochemical Cycles, 7, 843-878. APPENDIX I. Email Letter of Acknowledgement for CDIAC submittal: Subject: Re: OMP Data Revision & Methods Date: Fri, 4 May 2001 11:22:02 -0400 (EDT) From: Alexander Kozyr 1000 ms6335 40390 To: suth@ldeo.columbia.edu Dear Stew, Thank you for the data. I received the revised omp_pco2.rev1.txt file for Ocean Margins Program data. It consists of 9 legs (total 22, 355 records). I am planning to perform the CDIAC QA-QC procedure and put this file along with the methods information on CDIAC web site for public use. Regards, Alex. ******************************************* Alex Kozyr CDIAC Oceanographic Data Analyst The University of Tennessee Systems Development Institute 2360 Cherahala Boulevard Knoxville, TN 37932 USA Tel: (865)946-1480 Fax: (865)946-1492 Electronic address: akozyr@utk.edu Ocean CO2 WWW Page: http://cdiac.esd.ornl.gov/oceans/home.html *********************************************