ODV collection TCO2+TALK_son contains the September, October and November TCO2 and TALK estimates of Goyet, Healy, Ryan (2000) on a 1°x1° degree grid for the global ocean between 66.5°S and 66.5°N. The collection was constructed by merging files "tco2_son.dat" and "talk_son.dat" obtained from CDIAC as part of the NDP-076 package. In addition to TCO2 and TALK, there are temperature and salinity estimates from the two source files (distinguished by subscripts C and A, respectively) as well as winter mixed layer depths and AOU values. For further information on the original datasets see the documentation below. Reiner Schlitzer Alfred Wegener Institute for Polar and Marine Research Columbusstrasse 27568 Bremerhaven Germany March 2003 _______________________________________________________________________ ORNL/CDIAC-127 NDP-076 GLOBAL DISTRIBUTION OF TOTAL INORGANIC CARBON AND TOTAL ALKALINITY BELOW THE DEEPEST WINTER MIXED LAYER DEPTHS Contributed by Catherine Goyet,* Richard Healy,* and John Ryan** *Woods Hole Oceanographic Institution Woods Hole, Massachusetts **Monterey Bay Aquarium Research Institute Moss Landing, California Prepared by Alexander Kozyr*** Carbon Dioxide Information Analysis Center Oak Ridge National Laboratory Oak Ridge, Tennessee ***Energy, Environment, and Resources Center The University of Tennessee Knoxville, Tennessee Environmental Sciences Division Publication No. 4995 Date Published: May 2000 Prepared for the Environmental Sciences Division Office of Biological and Environmental Research U.S. Department of Energy Budget Activity Numbers KP 12 04 01 0 and KP 12 02 03 0 Prepared by the Carbon Dioxide Information Analysis Center OAK RIDGE NATIONAL LABORATORY Oak Ridge, Tennessee 37831-6335 managed by UT BATTELLE, LLC for the U.S. DEPARTMENT OF ENERGY under contract DE-AC05-00OR22725 ACKNOWLEDGEMENTS The authors would like to thank all oceanographers who went to sea, performed the measurements, and were responsible for the measurements of CO2 and hydrographic parameters. The authors also thank G. Monterey of Pacific Fisheries Environmental Laboratory, Pacific Grove, California, for MLD calculations at NODC. They thank the funding agencies: National Science Foundation, U.S. Department of Energy, NASA, and NOAA, for supporting the seagoing programs. This work was supported by NASA through Grant NAGW-2324. ABSTRACT Goyet, C., R. J. Healy, and J. P. Ryan. 2000. Global distribution of total inorganic carbon and total alkalinity below the deepest winter mixed layer depths. ORNL/CDIAC-127, NDP-076. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee. Modeling the global ocean-atmosphere carbon dioxide system is becoming increasingly important to greenhouse gas policy. These models require initialization with realistic three- dimensional (3-D) oceanic carbon fields. This report presents an approach to establishing these initial conditions from an extensive global database of ocean carbon dioxide (CO2) system measurements and well-developed interpolation methods. These methods are limited to waters below the deepest mixed layer. The data used for these interpolations include the recent high-quality data sets from the World Ocean Circulation Experiment (WOCE), Joint Global Ocean Flux Study (JGOFS), and Ocean-Atmosphere Carbon Exchange Study (OACES) programs. Prior to analysis, all carbon data were adjusted to established reference material listed in http://www-mpl.ucsd.edu/people/adickson/CO2_QC/. The interpolation methodology employs correlation between CO2 system properties and other more widely measured properties: potential temperature, salinity, and apparent oxygen utilization. The correlations are computed for each profile, and the coefficients are interpolated to the 1° × 1° × 32 vertical-layer grid at a monthly temporal resolution. Finally, the gridded coefficients are applied to a global monthly climatology of ocean temperature, salinity, and oxygen to compute total CO2 (TCO2) and total alkalinity (TALK) for the 3-D grid. This approach offers advantages over spin up of a single profile in defining spatial variation in CO2 system properties because it reduces initialization time and provides a more accurate carbon field. The results provide an unprecedented "view" of the global distribution of TALK and TCO2 in the ocean. These results as well as those from the monthly mixed layer depths can be used in diagnostic and prognostic global ocean models. The data set of the gridded climatological fields of TCO2, TALK, and mixed layer depths is available free of charge as a numeric data package from the Carbon Dioxide Information Analysis Center (CDIAC; http://cdiac.esd.ornl.gov/). The interpolated data set includes seasonal TCO2 and TALK fields as well as the coefficients used to estimate these concentrations and the monthly mixed layer depths. Keywords: Total carbon dioxide, total alkalinity, mixed layer depth, carbon fields, inorganic carbon, global ocean 1. INTRODUCTION One of the main objectives of the study of the oceanic carbon cycle is to quantify the present and future role of the ocean in the absorption of anthropogenic carbon dioxide (CO2). In situ data are typically used to quantify the present anthropogenic CO2 concentrations in the ocean (Brewer 1978; Chen and Millero 1979; Chen 1993; Wallace 1995; Gruber et al. 1996; Gruber 1998; Peng et al. 1998; Sabine et al. 1999; Goyet et al. 1999). Global ocean models are mainly used in a prognostic mode to estimate the future penetration of anthropogenic CO2 on the global scale (Sarmiento et al. 1992; Bhaskaran et al. 1995; Washington and Meehl 1996). Yet, accurate global initialization fields of the CO2 properties in seawater, such as total CO2 (TCO2) and total alkalinity (TALK), do not exist. In order to study the oceanic carbon cycle and to accurately describe and quantify the TCO2 and TALK fields on the global scale, TCO2 and TALK were measured with high accuracy throughout the water column of the major oceans. These measurements were mainly performed over the last two decades during intensive national and international field programs. Most of the data of these field programs are now freely available to the scientific community. However, these data need to be interpolated on a regular grid before they can easily be used in global ocean models. The purpose of this work is therefore to best interpolate these data on a regular grid for use in ocean models. The interpolation is based on each measured profile from the base of the mixed layer to the bottom of the ocean. The data within the mixed layer are not considered here because they are subject to large spatial and monthly variations that are still difficult to accurately quantify. The variations of the CO2 properties in the mixed layer are controlled by ocean circulation, evaporation/precipitation, dissolution of calcium carbonate, photosynthesis and oxidation of organic matter, and CO2 flux across the ocean-atmosphere interface including penetration of anthropogenic CO2. Many independent studies are currently designed to best quantify and parameterize each of these processes and the overall variations of the CO2 properties in the mixed layer (Takahashi et al. 1997; Millero et al. 1998). Below the mixed layer, TCO2 and TALK are controlled by ocean mixing, formation/dissolution of calcium carbonate, and oxidation of organic matter (Brewer 1978). In other words, short-timescale processes do not significantly affect TCO2 and TALK below the mixed layer. Thus it is possible to interpolate the data measured below the mixed layer at different times of year to acquire a reasonable understanding of the TCO2 and TALK fields. In ocean areas where anthropogenic CO2 is present (mainly in the upper 2000 m), it is also necessary to specify if and how data from different years are adjusted to a specific year before interpolation. In practice, the distribution of anthropogenic CO2 concentrations in the ocean is not accurately known. Estimates can differ significantly (Coatanoan et al. 2000) according to the various assumptions used. Until these differences are understood and considerably reduced, it will be very difficult to estimate pre-anthropogenic TCO2 fields on the global scale. Consequently, in this paper authors interpolate the measured TCO2 and TALK data without adjustment for the variations in anthropogenic CO2 concentration for a given year. Because most of the data were measured within the past twenty years, such small adjustment to the different data sets (except for the North Atlantic Ocean) would mainly be within the uncertainty of the interpolated field. The results provide an estimate of these fields for the mid-1990s, when most of the accurate measurements were performed. 2. DATA SETS AND METHODS In order to interpolate the measured TCO2 and TALK data, the available observations were assembled (Table 1). Measurements prior to 1990 did not use the accurate standards established by Dickson (1997) for calibrating TCO2. Therefore pre-1990 profiles were adjusted by comparing deep measurements within 1° of latitude and longitude, as described for the Atlantic Ocean (Goyet et al. 1997), the Pacific Ocean (Feely et al. 1998), and the Indian Ocean (Sabine et al. 1999). All the TALK measurements were performed by potentiometry (Dyrssen 1965; Millero et al. 1998). Most of the TCO2 measurements were performed by extraction/coulometry (Johnson et al. 1985, 1987, 1993, 1998) except for the cruises prior to 1990 where TCO2 was measured by potentiometry. All these measurements are described in detail in the Handbook of Methods for the Analysis of the Various Parameters of the Carbon Dioxide System in Sea Water (DOE 1994). Table 1. Summary of data sets used for interpolation of the TCO2 and TALK fields on the global scale ------------------------------------------------------------------- Field program Reference ------------------------------------------------------------------- GEOSECS1 Takahashi et al. 1980 INDIGO2 Poisson et al. 1988, 1989, 1990 JGOFS3 http://www1.whoi.edu/jgofs.html OACES4 NOAA8; http://www.aoml.noaa.gov/ocd/oaces TTO5 Data reports, TTO 1986a,b WOCE6; SAVE7 CDIAC; http://cdiac.esd.ornl.gov/oceans/home.html --------------------------------------------------------------------- 1 Geochemical Ocean Sections 2 Indian Ocean Global Observation 3 Joint Global Ocean Flux Study 4 Ocean-Atmosphere Carbon Exchange Study 5 Transient Tracers in the Ocean 6 World Ocean Circulation Experiment 7 South Atlantic Ventilation Experiment 8 National Oceanographic and Atmospheric Administration 2.1 Determination of Monthly Mixed Layer Depth Fields In order to define monthly mixed layer depth (MLD), a weighted average based on two sources of MLD information was created, one source based on observations and the other based on a numerical ocean model. The first was the MLD product offered by the National Ocean Data Center (NODC). Specifically, the MLD fields computed via potential density at 1° × 1° from gridded temperature/salinity (T/S) (Levitus and Boyer 1994a; Levitus et al. 1994) were used. This product is available at http://www.cdc.noaa.gov/cdc/data.nodc.woa94.html. The second source was Fleet Numerical Meteorology and Oceanography Center (FNMOC) model mixed layer output at a resolution of 2.5° × 2.5° (Clancy and Sadler 1992). Using daily FNMOC fields from March through December 1995 and January and February, 1996, monthly means were computed and then gridded to the same resolution as the NODC fields. The T/S observations required for the NODC MLD product are highly non-uniformly distributed over the globe, and much of the ocean is completely unsampled (see Levitus and Boyer 1994a for methodology of filling the global 1° × 1° grid). As a result, the MLD fields contain unrealistic spatial distributions, horizontal gradients, and magnitudes. This problem with definition of MLD from gridded T/S is known, and a developing approach is to define MLD from individual hydrographic profiles and to grid resultant MLD estimates only where observations exist (Monterey, G., Pacific Fisheries Environmental Laboratory, Pacific Grove, Calif., personal communication.). However, such MLD fields are not currently available. Therefore, a weighting function for the NODC MLD fields was defined based on observation density. Specifically, we used the monthly average number of salinity observations at NODC levels within the upper 50 m. Based on mapped observation density, a cutoff of 75 was chosen to define where salinity was well sampled and thus where the NODC MLD fields had a sufficient observational base. Above this cutoff, the weighting for NODC MLD was 1 ( 7% of the grid points). Below the cutoff, the weighting for NODC MLD was the average number of observations divided by 75. Lastly, because some NODC MLD values are extremely and unrealistically deep where few observations exist, zero weighting was assigned where NODC MLD was > 400 m. This weighting procedure retained NODC MLD estimates in relatively well-observed regions and relied on the model (FNMOC) MLD estimates for poorly observed regions (in proportion to the paucity of observations). Following this definition of the weighted average MLD product, there still remained grid points where neither input data set provided information. Missing grid points within the latitude range 65° N to 65° S were filled with a combination of spatial and temporal averaging (±2 months and 5° of latitude/longitude). Any points not filled by this procedure were filled with the mean of all valid monthly MLD values for that grid point. Finally, a 5°×5° median filter was applied to the monthly MLD fields to smooth the boundaries where missing data were filled in the last step. 2.2 Interpolation of TALK Below the Deepest Mixed Layer Below the mixed layer, TALK can be interpolated by piecewise linear regression as a function of potential temperature (PT) and salinity (S): TALK = a + bPT + cS (1) One regression was performed in each of the two layers: from the wintertime mixed layer down to 1000 m, and below 1000 m. The cutoff at 1000 m reflects the mean depth of the TALK maximum. The coefficients were calculated for each profile, interpolated to the 3-D grid using the Generic Mapping Tools (GMT) software (Wessel and Smith 1995), and applied to climatological temperature and salinity (Levitus and Boyer 1994a,b; Levitus et al. 1994) to compute TALK. Uncertainty associated with this interpolation procedure in the Indian, Pacific, and Atlantic Oceans is respectively estimated to be ±8.4 µmol/kg, ±10.2 µmol/kg, and ±4.6 µmol/kg in the upper 1000 m, and ±4.8 µmol/kg, ±9.1 µmol/kg, and ±5.9 µmol/kg at depths below 1000 m. The mean uncertainty associated with the TALK interpolation procedure in the global ocean below the mixed layer is estimated to be ±5.5 µmol/kg. 2.3 Interpolation of TCO2 Below the Deepest Mixed Layer As shown earlier (Goyet and Davis 1997), below the winter mixed layer, TCO2 can be interpolated as a function of potential temperature (PT), apparent oxygen utilization (AOU), and salinity (S): TCO2 = a + bPT + cAOU + dS (2) The coefficients were calculated for each profile, interpolated to the 3-D grid using the GMT software, and applied to climatological hydrographic properties to compute TCO2 at the grid points below the deepest winter mixed layer depth. Uncertainty associated with this interpolation procedure in the Indian, Pacific, and Atlantic Oceans is respectively estimated to be ±7.9 µmol/kg, ±14.5 µmol/kg, and ±8.1 µmol/kg. The mean uncertainty associated with the TCO2 interpolation procedure in the global ocean below the mixed layer is estimated to be ±9.4 µmol/kg. The uncertainty is the largest in the Pacific Ocean and reflects the relatively poor data density in this large ocean. 3. RESULTS The results of this work are monthly global fields of TCO2 and TALK, the coefficients used to compute these CO2 system properties, and the maximum mixed layer depths used to define the shallowest depth for these computations. Figure 1 (in hard copy) shows the geographical distribution of the maximum depth of the mixed layer. The deepest mixed layers are observed in the northern Atlantic Ocean. The Southern Ocean south of 50° S is a large area with deep mixed layers as a result of the strong atmospheric forcing. The shallowest (< 20 m) mixed layers are observed at low latitudes. Figures 2 and 3 (in hard copy) illustrate the annual mean concentrations of TCO2 and TALK, respectively, at 500 m, 1500 m, and 3500 m between 60° N and 60° S. These maps clearly show the differences between the three major oceans. In the Pacific Ocean, TCO2 concentrations are generally higher on the eastern side than on the western side. At 500 m, TCO2 concentrations have the signature of the upper layers and reflect the circulation patterns. The equatorial upwelling is particularly evident with TCO2 concentrations higher on the eastern side than the western side. At 1500 m, the highest concentrations are observed in the Pacific Ocean north of 35° N, while the lowest concentrations are observed in the Atlantic Ocean north of 35° N. At 3500 m, TCO2 concentrations in the Indian Ocean are comparable to those in the Pacific Ocean at similar latitudes. The lowest TCO2 concentrations are observed in the northwestern Atlantic Ocean. At 3500 m, TCO2 concentrations typically differ by 200 µmol/kg or more between the different ocean basins of the Northern Hemisphere. In contrast, in the Southern Hemisphere south of 40° S, the variation of TCO2 concentration between oceans is typically less than 50 µmol/kg. At 500 m, TALK is lowest in the Pacific Ocean. However, at 1500 and 3500 m, TALK is lowest in the Atlantic Ocean. In contrast to TCO2, the highest TALK concentrations are in the northern Indian Ocean. Overall, the distribution of TCO2 and TALK in seawater reflects the circulation of the different water masses. Briefly, in the North Atlantic Ocean the waters are young and the concentration of TCO2 is relatively low, whereas the concentration of TALK is relatively high. However, because it is a location of deep water formation, the TCO2 gradient from the surface to the bottom is relatively small, and anthropogenic CO2 penetrates to the bottom (Chen 1993). From the North Atlantic Ocean the water flows to the South Atlantic Ocean and to the Southern Ocean before going into the North Indian and North Pacific Oceans, where TCO2 concentrations are the highest. 4. SUMMARY Understanding the complex, interacting processes that determine global ocean uptake of atmospheric CO2 requires accurate definition of initial conditions and accurate representation of the processes forcing variation. An approach to defining global, monthly 3-D fields of TCO2 and TALK below the deepest mixed layer was presented in this report. These fields are now available to the scientific community through CDIAC. The accuracy of these interpolated fields is the best available today given the in situ data fields. They accurately reflect the main characteristics of global water mass circulation. This approach offers advantages over spin up of a single profile in defining spatial variation in CO2 system properties because it provides a more accurate carbon field and reduces initialization time. As additional data become available, it will be possible to increase the accuracy of mixed layer depths, TCO2, and TALK fields. 5. HOW TO OBTAIN THE DATA AND DOCUMENTATION This database (NDP-076) is available free of charge from CDIAC. The data are available from CDIAC's anonymous file transfer protocol (FTP) area via the Internet. Please note: Your computer needs to have FTP software loaded on it (this is built in to most newer operating systems). Use the following commands to obtain the database. >ftp cdiac.esd.ornl.gov or >ftp 128.219.24.36 Login: "anonymous" or "ftp" Password: your e-mail address ftp> cd pub/ndp076/ ftp> dir ftp> mget (files) ftp> quit The complete documentation and data can also be obtained from the CDIAC oceanographic Web site (http://cdiac.esd.ornl.gov/oceans/doc.html), through CDIAC's online ordering system (http://cdiac.esd.ornl.gov/pns/how_order.html), or by contacting CDIAC. Contact information: Carbon Dioxide Information Analysis Center Oak Ridge National Laboratory P.O. Box 2008 Oak Ridge, Tennessee 37831-6335 U.S.A. Telephone: 865-574-3645 Telefax: 865-574-2232 E-mail: cdiac@ornl.gov Internet: http://cdiac.esd.ornl.gov/ 6. REFERENCES Bhaskaran, B., J. F. B. Mitchell, J. Lavery, and M. Lal. 1995. Climatic response of Indian subcontinent to doubled CO2 concentration. International Journal of Climatology 15:873-92. Brewer, P. G. 1978. Direct observation of the oceanic CO2 increase. Geophysical Research Letters 5:997-1000. Chen, C.-T. 1993. The oceanic anthropogenic CO2 sink. Chemosphere 27:1041-64. Chen, C.-T., and F. J. Millero. 1979. Gradual increase of oceanic CO2. Nature 277:205-6. Clancy, R. M., and W. D. Sadler. 1992. The Fleet Numerical Meteorology and Oceanography Center suite of oceanographic models and products. Weather and Forecasting 7:307-27. Coatanoan C., C. Goyet, N. Gruber, C. L. Sabine, and M. Warner. 2000. Comparison of the two approaches to quantify anthropogenic CO2 in the ocean: Results from the northern Indian Ocean. Global Biogeochemical Cycle (in press). Dickson A. G. (1997). Reference material batch information. http://www-mpl.ucsd.edu/people/adickson/CO2_QC/level1/Batches.html DOE (U.S. Department of Energy). 1994. Handbook of methods for analysis of the various parameters of the carbon dioxide system in seawater: Version 2. ORNL/CDIAC-74. A. G. Dickson and C. Goyet (eds.). Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tenn. Dyrssen, D. 1965. A Gran titration of sea water on board Sagitta. Acta Chemica Scandinavica 19(5):1265. Feely, R. A., M. F. Lamb, D. J. Greeley, and R. Wanninkhof. 1999. Comparison of the carbon system parameters at the global CO2 survey crossover locations in the North and South Pacific Ocean, 1990-1996. ORNL/CDIAC-115. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A. Goyet, C., R. Healy, S. J. McCue, and D. M. Glover. 1997. Interpolation of TCO2 data on a 1°×1° grid throughout the water column below 500 m depth in the Atlantic Ocean. Deep-Sea Research I 44(12):1945-55. Goyet C., and D. Davis. 1997. Estimation of total CO2 concentration throughout the water column. Deep-Sea Research I 44(5):859-77 Goyet, C., C. Coatanoan, G. Eischeid, T. Amaoka, K. Okuda, R. Healy, and S. Tsunogai. 1999. Spatial variation of total CO2 and total alkalinity in the northern Indian Ocean: A novel approach for the quantification of anthropogenic CO2 in seawater. Journal of Marine Research 57:135-63. Gruber, N. 1998. Anthropogenic CO2 in the Atlantic Ocean. Global Biogeochemical Cycles 12(1):165-91. Johnson, K. M., A. E. King, and J. M. Sieburth. 1985. Coulometric TCO2 analyses for marine studies: An introduction. Marine Chemistry 16:61-82. Johnson, K. M., J. M. Sieburth, P. J. L. Williams, and L. Brandstrom. 1987. Coulometric total carbon dioxide analysis for marine studies: Automation and calibration. Marine Chemistry 21:117-33. Johnson, K. M., K. D. Wills, D. B. Butler, W. K. Johnson, and C. S. Wong. 1993. Coulometric total carbon dioxide analysis for marine studies: Maximizing the performance of an automated continuous gas extraction system and coulometric detector. Marine Chemistry 44:167-87. Johnson, K. M., A. G. Dickson, G. Eischeid, C. Goyet, P. Guenther, F. J. Millero, D. Purkerson, C. L. Sabine, R. G. Schottle, D. R. W. Wallace, R. J. Wilke, and C. D. Winn. 1998. Coulometric total carbon dioxide analysis for marine studies: Assessment of the quality of total inorganic carbon measurements made during the U.S. Indian Ocean CO2 1994 1996. Marine Chemistry 63:21-37. Levitus, S., R. Burgett, and T. P. Boyer. 1994. World Ocean Atlas (1994). Vol. 3: Salinity. NOAA Atlas NESDIS 3, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, Washington, D.C. Levitus, S., and T. P. Boyer. 1994a. World Ocean Atlas (1994). Vol. 4: Temperature. NOAA Atlas NESDIS 4, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, Washington, D.C. Levitus, S., and T. P. Boyer. 1994b. World Ocean Atlas (1994). Vol. 2: Oxygen. NOAA Atlas NESDIS 2, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, Washington, D.C. Millero, F. J., K. Lee, and M. Roche. 1998. Distribution of alkalinity in the surface waters of the major oceans. Marine Chemistry 60:111-30. Peng, T.-H., R. Wanninkhof, J. L. Bullister, R. A. Feely, and T. Takahashi. 1998. Quantification of decadal anthropogenic CO2 uptake in the ocean based on dissolved inorganic carbon measurements. Nature 396:560-63. Poisson, A., B. Schauer, and C. Brunet. 1988. Les rapports des campagnes à la mer à bord du Marion Dufresne. MD 43/INDIGO 1. No. 85-06. In Les publications de la mission de recherche des Terres Australes et Antarctiques Françaises. Paris, France. Poisson, A., B. Schauer, and C. Brunet. 1989. Les rapports des campagnes à la mer à bord du Marion Dufresne. MD 49/INDIGO 2. No. 86-03. In Les publications de la mission de recherche des Terres Australes et Antarctiques Françaises. Paris, France. Poisson, A., B. Schauer, and C. Brunet. 1990. Les rapports des campagnes à la mer à bord du Marion Dufresne. MD 53/INDIGO 3. No. 87-02. In Les publications de la mission de recherche des Terres Australes et Antarctiques Françaises. Paris, France. Takahashi, T., W. S. Broecker, A. E. Brainbridge, and R. F. Weiss. 1980. Carbonate chemistry of the Atlantic, Pacific, and Indian Oceans: The results of the GEOSECS Expeditions, 1972 1978. Technical Report, 1, CU-1-80. Lamont-Doherty Geological Observatory, Palisades, N.Y. Takahashi, T., R. A. Feely, R. F. Weiss, R. H. Wanninkhof, D. W. Chipman, and S. C. Sutherland. 1997. Global air-sea flux of CO2: An estimate based on measurements of sea-air CO2 difference. Proceedings of the National Academy of Science 94:8292-99. TTO (Transient Tracers in the Ocean). 1986a. North Atlantic Study, 1 April 19 October 1981. Data report SIO No. 86-15, PACODF publication No. 221. Scripps Institution of Oceanography, La Jolla, Calif. TTO. 1986b. Tropical Atlantic Study, 1 December 1982 18 February 1983. Data report SIO No. 86-16, PACODF publication No. 222. Scripps Institution of Oceanography, La Jolla, Calif. Sabine C. L., R. M. Key, K. M. Johnson, F. J. Millero, A. Poisson, J. L. Sarmiento, D. W. R. Wallace, and C. D. Winn. 1999. Anthropogenic CO2 inventory of the Indian Ocean. Global Biogeochemical Cycles 13(1):179-98. Sarmiento J. C., J. C. Orr, and U. Siegenthaler. 1992. A perturbation simulation of CO2 uptake in an ocean general circulation model. Journal of Geophysical Research 97:3621-46. Wallace, D. W. R. 1995. Monitoring global ocean carbon inventories. Ocean Observing System Development panel. Texas A & M University, College Station, Texas. Washington, W. M., and G. A. Meehl. 1996. High latitude climate change in a global coupled ocean-atmosphere-sea ice model with increased atmospheric CO2. Journal of Geophysical Research 101(D8):12795-801. Wessel, P., and W. H. F. Smith. 1995. New version of the generic mapping tools released. EOS Transactions American Geophysical Union 76:329. 7. FILE DESCRIPTIONS This section describes the content and format of each of the 19 files that comprise this numeric data package (NDP) (see Table 2). Because CDIAC distributes the data set in several ways (e.g., via anonymous FTP and on floppy diskette), each of the 19 files is referenced by both an ASCII file name, which is given in lowercase, bold-faced type (e.g., ndp076.txt) and a file number. The remainder of this section describes (or lists, where appropriate) the contents of each file. Table 2. Content, size, and format of data files --------------------------------------------------------------------------------------------- File number, name, Logical File size and description records in bytes --------------------------------------------------------------------------------------------- 1. ndp076.txt: 1,094 58,117 a detailed description of the data set, methods of calculations of carbon fields, the five FORTRAN 77 data-retrieval routines, and the thirteen oceanographic data files 2. coef_talk.for: 45 1,430 a FORTRAN 77 data-retrieval routine to read and print coef_talk.dat (File 7) 3. coef_tco2.for: 39 1,160 a FORTRAN 77 data-retrieval routine to read and print coef_tco2.dat (File 8) 4. mld1x1.for: 47 1,631 a FORTRAN 77 data-retrieval routine to read and print mld1x1.dat (File 9) 5. talkdat.for: 44 1,456 a FORTRAN 77 data-retrieval routine to read and print talk_*.dat (Files 10 14) 6. tco2dat.for: 41 1,285 a FORTRAN 77 data-retrieval routine to read and print tco2_*.dat (Files 15 19) 7. coef_talk.dat: 48,387 4,403,002 a listing of the a, b, and c coefficients used to calculate TALK fields 8. coef_tco2.dat: 48,387 3,096,806 a listing of the a, b, c, and d coefficients used to calculate TCO2 fields 9. mld1x1.dat: 34,144 4,574,721 mixed layer depths (1°×1° grid) calculated for each month of the year 10-14. talk_*.dat: 4,973,480 447,612,905 interpolated TALK fields calculated annually and for each quarter 15-19. tco2_*.dat: 4,980,110 323,714,083 interpolated TCO2 fields calculated annually and for each quarter ____________ ____________ Total 10,085,818 783,466,596 ------------------------------------------------------------------------------------------ 7.1 ndp076.txt (File 1) This file contains a detailed description of the data set, methods of calculations, the five FORTRAN 77 data-retrieval routines, and the thirteen oceanographic data files. It exists primarily for the benefit of individuals who acquire this database as machine-readable data files from CDIAC. 7.2 coef_talk.for (File 2) This file contains a FORTRAN 77 data-retrieval routine to read and print coef_talk.dat (File 7). The following is a listing of this program. For additional information regarding variable definitions, variable lengths, variable types, units, and codes, please see the description for coef_talk.dat in Sect. 7.7. c******************************************************************** c* FORTRAN 77 data retrieval routine to read and print the file c* named "coef_talk.dat" (File 7) c******************************************************************** c*Defines variables* REAL lon, lat, coef1, coef2, coef3, coef4, coef5 REAL coef6 OPEN (unit=1, file='coef_talk.dat') OPEN (unit=2, file='coef_talk.txt') write (2, 5) c*Writes out column labels* 5 format (2X,'LONG',4X,'LAT',2X,'A_COEFF_OFST',1X, 1 'A_COEFF_OFST',2X,'B_COEFF_TMP',2X,'B_COEFF_TMP', 2 1X,'C_COEFF_SAL',1X,'C_COEFF_SAL',/,3X,'DEG',4X, 3 'DEG',5X,'MLD-1000M',7X,'>1000M',4X,'MLD-1000M', 4 7X,'>1000M',3X,'MLD-1000M',6X,'>1000M') c*Sets up a loop to read and format all the data in the file* read (1, 6) 6 format (///////////) 7 CONTINUE read (1, 10, end=999) lon, lat, coef1, coef2, coef3, coef4, 1 coef5, coef6 10 format (F6.1, 1X, F6.1, 2X, F12.4, 1X, F12.4, 1X, F12.5, 1 1X, F12.5, 1X, F11.4, 1X, F11.4) write (2, 20) lon, lat, coef1, coef2, coef3, coef4, 1 coef5, coef6 20 format (F6.1, 1X, F6.1, 2X, F12.4, 1X, F12.4, 1X, F12.5, 1 1X, F12.5, 1X, F11.4, 1X, F11.4) GOTO 7 999 close(unit=1) close(unit=2) stop end 7.3 coef_tco2.for (File 3) This file contains a FORTRAN 77 data-retrieval routine to read and print coef_tco2.dat (File 8). The following is a listing of this program. For additional information regarding variable definitions, variable lengths, variable types, units, and codes, please see the description for coef_tco2.dat in Sect. 7.8. c**************************************************************** c* FORTRAN 77 data retrieval routine to read and print the file c* named "coef_tco2.dat" (File 8) c**************************************************************** c*Defines variables* REAL lon, lat, coefa, coefb, coefc, coefd OPEN (unit=1, file='coef_tco2.dat') OPEN (unit=2, file='coef_tco2.txt') write (2, 5) c*Writes out column labels* 5 format (2X,'LONG', 4X,'LAT',6X,'A_COEFF',5X,'B_COEFF', 1 6X,'C_COEFF',5X,'D_COEFF',/,3X,'DEG',4X,'DEG') c*Sets up a loop to read and format all the data in the file* read (1, 6) 6 format (///////////) 7 CONTINUE read (1, 10, end=999) lon, lat, coefa, coefb, coefc, coefd 10 format (F6.1, 1X, F6.1, 2X, F11.4, 1X, F11.5, 1X, F12.6, 1 1X, F11.5) write (2, 20) lon, lat, coefa, coefb, coefc, coefd 20 format (F6.1, 1X, F6.1, 2X, F11.4, 1X, F11.5, 1X, F12.6, 1 1X, F11.5) GOTO 7 999 close(unit=1) close(unit=2) stop end 7.4 mld1x1.for (File 4) This file contains a FORTRAN 77 data-retrieval routine to read and print mld1x1.dat (File 9). The following is a listing of this program. For additional information regarding variable definitions, variable lengths, variable types, units, and codes, please see the description for mld1x1.dat in Sect. 7.9. c******************************************************************** c* FORTRAN 77 data retrieval routine to read and print the file c* named "mld1x1.dat" (File 9) c******************************************************************** c*Defines variables* REAL lon, lat, max, jan, feb, mar, apr, may, jun, jul REAL aug, sep, oct, nov, dec OPEN (unit=1, file='mld1x1.dat') OPEN (unit=2, file='mld1x1.txt') write (2, 5) c*Writes out column labels* 5 format (4X,'LONG',5X,'LAT',2X,'MLD_MAX',2X,'MLD_JAN', 1 2X,'MLD_FEB',2X,'MLD_MAR',2X,'MLD_APR',2X,'MLD_MAY', 2 2X,'MLD_JUN',2X,'MLD_JUL',2X,'MLD_AUG',2X,'MLD_SEP', 3 2X,'MLD_OCT',2X,'MLD_NOV',2X,'MLD_DEC',/, 4 5X,'DEG',5X,'DEG',8X,13('M',8X)) c*Sets up a loop to read and format all the data in the file* read (1, 6) 6 format (//////////) 7 CONTINUE read (1, 10, end=999) lon, lat, max, jan, feb, mar, 1 apr, may, jun, jul, aug, sep, oct, nov, dec 10 format (F8.2, 1X, F7.2, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, 2 F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4) write (2, 20) lon, lat, max, jan, feb, mar, 1 apr, may, jun, jul, aug, sep, oct, nov, dec 20 format (F8.2, 1X, F7.2, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, 2 F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4) GOTO 7 999 close(unit=1) close(unit=2) stop end 7.5 talkdat.for (File 5) This file contains a FORTRAN 77 data-retrieval routine to read and print talk_*.dat (Files 10-14). The following is a listing of this program. For additional information regarding variable definitions, variable lengths, variable types, units, and codes, please see the description for talk_*.dat in Sect. 7.10. c******************************************************************** c* FORTRAN 77 data retrieval routine to read and print the files c* named "talk_*.dat" (Files 10-14) c******************************************************************** c*Defines variables* REAL lon, lat, dep, mld, talk, tmp, sal, coefa, coefb REAL coefc OPEN (unit=1, file='talk_*.dat') OPEN (unit=2, file='talk_*.txt') write (2, 5) c*Writes out column labels* 5 format (3X,'LONG',4X,'LAT',3X,'DEPTH',5X,'MLD',6X, 1'TALK', 4X,'TEMP',2X,'SALNTY',4X,'A_COEFF',4X, 2 'B_COEFF',4X,'C_COEFF',/,4X,'DEG',4X,'DEG',7X,'M', 3 7X,'M',3X,'UMOL/KG',5X,'DEG',2X,'PSS-78',5X,'OFFSET', 4 7X,'TEMP',5X,'SALNTY',/) c*Sets up a loop to read and format all the data in the file* read (1, 6) 6 format (///////////) 7 CONTINUE read (1, 10, end=999) lon, lat, dep, mld, talk, tmp, 1 sal, coefa, coefb, coefc 10 format (F7.1, 1X, F6.1, 1X, F7.1, 1X, F7.1, 1X, F9.1, 1 1X, F7.3, 1X, F7.3, 1X, F10.3, 1X, F10.3, 1X, F10.3) write (2, 20) lon, lat, dep, mld, talk, tmp, 1 sal, coefa, coefb, coefc 20 format (F7.1, 1X, F6.1, 1X, F7.1, 1X, F7.1, 1X, F9.1, 1 1X, F7.3, 1X, F7.3, 1X, F10.3, 1X, F10.3, 1X, F10.3) GOTO 7 999 close(unit=1) close(unit=2) stop end 7.6 tco2dat.for (File 6) This file contains a FORTRAN 77 data-retrieval routine to read and print tco2_*.dat (Files 15-19). The following is a listing of this program. For additional information regarding variable definitions, variable lengths, variable types, units, and codes, please see the description for tco2_*.dat in Sect. 7.11. cc******************************************************************* c* FORTRAN 77 data retrieval routine to read and print the files c* named "tco2_*.dat" (Files 15-19) c******************************************************************** c*Defines variables* REAL lon, lat, dep, mld, trco2, tmp, aou, sal OPEN (unit=1, file='tco2_*.dat') OPEN (unit=2, file='tco2_*.txt') write (2, 5) c*Writes out column labels* 5 format (3X,'LONG',4X,'LAT',3X,'DEPTH',5X,'MLD',6X,'TCO2', 1 4X,'TEMP',5X,'AOU',2X,'SALNTY',/,4X,'DEG',4X,'DEG',7X,'M', 2 7X,'M',3X,'UMOL/KG',5X,'DEG',1X,'UMOL/KG',2X,'PSS-78',/) c*Sets up a loop to read and format all the data in the file* read (1, 6) 6 format (///////////) 7 CONTINUE read (1, 10, end=999) lon, lat, dep, mld, trco2, tmp, 1 aou, sal 10 format (F7.1, 1X, F6.1, 1X, F7.1, 1X, F7.1, 1X, F9.1, 1 1X, F7.3, 1X, F7.3, 1X, F7.3) write (2, 20) lon, lat, dep, mld, trco2, tmp, aou, sal 20 format (F7.1, 1X, F6.1, 1X, F7.1, 1X, F7.1, 1X, F9.1, 1 1X, F7.3, 1X, F7.3, 1X, F7.3) GOTO 7 999 close(unit=1) close(unit=2) stop end 7.7 coef_talk.dat (File 7) This file provides the coefficients a, b, and c used to calculate TALK from the potential temperature (T) and salinity (S). Each line of the file contains a longitude, latitude, offset coefficient a (between depths MLD and 1000 m), offset coefficient a (below 1000 m), T coefficient b (between depths MLD and 1000 m), T coefficient b (below 1000 m), S coefficient c (between depths MLD and 1000 m), and S coefficient c (below 1000 m). The file is sorted by longitude and latitude and can be read by using the following FORTRAN 77 code (contained in coef_talk.for, File 2): REAL lon, lat, coef1, coef2, coef3, coef4, coef5 REAL coef6 read (1, 10, end=999) lon, lat, coef1, coef2, coef3, coef4, 1 coef5, coef6 10 format (F6.1, 1X, F6.1, 2X, F12.4, 1X, F12.4, 1X, F12.5, 1 1X, F12.5, 1X, F11.4, 1X, F11.4) Stated in tabular form, the contents include the following: ------------------------------------------------------------------- Variable Variable Variable Starting Ending type width column column ------------------------------------------------------------------- lon Numeric 6 1 6 lat Numeric 6 8 13 coef1 Numeric 12 16 27 coef2 Numeric 12 29 40 coef3 Numeric 12 42 53 coef4 Numeric 12 55 66 coef5 Numeric 11 68 78 coef6 Numeric 11 80 90 ------------------------------------------------------------------- The variables are defined as follows: lon is the longitude for which coefficients were calculated; lat is the latitude for which coefficients were calculated; coef1 is the offset coefficient a (for depths between MLD and 1000 m); coef2 is the offset coefficient a (for depths below 1000 m); coef3 is the T coefficient b (for depths between MLD and 1000 m); coef4 is the T coefficient b (for depths below 1000 m); coef5 is the S coefficient c (for depths between MLD and 1000 m); and coef6 is the S coefficient c (for depths below 1000 m). 7.8 coef_tco2.dat (File 8) This file provides the coefficients a, b, c, and d used to calculate TCO2 from the T, apparent oxygen utilization (AOU), and S. Each line of the file contains a longitude, latitude, offset coefficient a (below MLD), T coefficient b (below MLD), AOU coefficient c (below 1000 m), and S coefficient d (below MLD). The file is sorted by longitude and latitude and can be read by using the following FORTRAN 77 code (contained in coef_tco2.for, File 3): REAL lon, lat, coefa, coefb, coefc, coefd read (1, 10, end=999) lon, lat, coefa, coefb, coefc, coefd 10 format (F6.1, 1X, F6.1, 2X, F11.4, 1X, F11.5, 1X, F12.6, 1 1X, F11.5) Stated in tabular form, the contents include the following: -------------------------------------------------------------------- Variable Variable Variable Starting Ending type width column column -------------------------------------------------------------------- lon Numeric 6 1 6 lat Numeric 6 8 13 coefa Numeric 11 16 26 coefb Numeric 11 28 38 coefc Numeric 12 40 51 coefd Numeric 11 53 63 -------------------------------------------------------------------- The variables are defined as follows: lon is the longitude for which coefficients were calculated; lat is the latitude for which coefficients were calculated; coefa is the offset coefficient a (for depths below MLD); coefb is the T coefficient b (for depths below MLD); coefc is the AOU coefficient c (for depths below MLD; and coefd is the S coefficient d (for depths below MLD). 7.9 mld1x1.dat (File 9) This file provides a mixed layer depths (1° × 1° grid) calculated for each month of the year. The file is sorted by longitude and latitude and can be read by using the following FORTRAN 77 code (contained in mld1x1.for, File 4): REAL lon, lat, max, jan, feb, mar, apr, may, jun, jul REAL aug, sep, oct, nov, dec read (1, 10, end=999) lon, lat, max, jan, feb, mar, 1 apr, may, jun, jul, aug, sep, oct, nov, dec 10 format (F8.2, 1X, F7.2, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, 2 F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4, 1X, F8.4) Stated in tabular form, the contents include the following: ------------------------------------------------------------------ Variable Variable Variable Starting Ending type width column column ------------------------------------------------------------------ lon Numeric 8 1 8 lat Numeric 7 10 16 max Numeric 8 18 25 jan Numeric 8 27 34 feb Numeric 8 36 43 mar Numeric 8 45 52 apr Numeric 8 54 61 may Numeric 8 63 70 jun Numeric 8 72 79 jul Numeric 8 81 88 aug Numeric 8 90 97 sep Numeric 8 99 106 oct Numeric 8 108 115 nov Numeric 8 117 124 dec Numeric 8 126 133 The variables are defined as follows: lon is the longitude for which MLDs were calculated; lat is the latitude for which MLDs were calculated; max is the year maximum MLD; jan dec is the calculated MLD for each month of the year. 7.10 talk_*.dat (Files 10-14) These files provide the interpolated TALK fields calculated annually and for each quarter (talk_ann.dat, talk_djf.dat, talk_mam.dat, talk_jja.dat, and talk_son.dat). The files are sorted by longitude and latitude and can be read by using the following FORTRAN 77 code (contained in talkdat.for, File 5): REAL lon, lat, dep, mld, talk, tmp, sal, coefa, coefb REAL coefc read (1, 10, end=999) lon, lat, dep, mld, talk, tmp, 1 sal, coefa, coefb, coefc 10 format (F7.1, 1X, F6.1, 1X, F7.1, 1X, F7.1, 1X, F9.1, 1 1X, F7.3, 1X, F7.3, 1X, F10.3, 1X, F10.3, 1X, F10.3) Stated in tabular form, the contents include the following: ------------------------------------------------------------------ Variable Variable Variable Starting Ending type width column column ------------------------------------------------------------------ lon Numeric 7 1 7 lat Numeric 6 9 14 dep Numeric 7 16 22 mld Numeric 7 24 30 talk Numeric 9 32 40 tmp Numeric 7 42 48 sal Numeric 7 50 56 coefa Numeric 10 58 67 coefb Numeric 10 69 78 coefc Numeric 10 80 89 ------------------------------------------------------------------- The variables are defined as follows: lon is the longitude for which TALK was calculated; lat is the latitude for which TALK was calculated; dep is the depth for which TALK was calculated (m); mld is the maximum layer depth (m); talk is the total alkalinity (µmol/kg); tmp is the temperature (°C); sal is the salinity; coefa is the a coefficient (offset); coefb is the b coefficient to temperature; and coefc is the c coefficient to salinity. 7.11 tco2_*.dat (Files 15 19) These files provide the interpolated TCO2 fields calculated annually and for each quarter (tco2_ann.dat, tco2_djf.dat, tco2_mam.dat, tco2_jja.dat, and tco2_son.dat). The files are sorted by longitude and latitude and can be read by using the following FORTRAN 77 code (contained in tco2dat.for, File 6): REAL lon, lat, dep, mld, trco2, tmp, aou, sal read (1, 10, end=999) lon, lat, dep, mld, trco2, tmp, 1 aou, sal 10 format (F7.1, 1X, F6.1, 1X, F7.1, 1X, F7.1, 1X, F9.1, 1 1X, F7.3, 1X, F7.3, 1X, F7.3) Stated in tabular form, the contents include the following: ------------------------------------------------------------------ Variable Variable Variable Starting Ending type width column column ------------------------------------------------------------------ lon Numeric 7 1 7 lat Numeric 6 9 14 dep Numeric 7 16 22 mld Numeric 7 24 30 tco2 Numeric 9 32 40 tmp Numeric 7 42 48 aou Numeric 7 50 56 sal Numeric 7 58 64 ------------------------------------------------------------------ The variables are defined as follows: lon is the longitude for which TCO2 was calculated; lat is the latitude for which TCO2 was calculated; dep is the depth for which TCO2 was calculated (m); mld is the maximum layer depth (m); tco2 is the total carbon dioxide ( µmol/kg); tmp is the temperature (°C); aou is the apparent oxygen utilization ( µmol/kg); and sal is the salinity.