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ISLSCP II Air-Sea Carbon Dioxide Gas Exchange

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Revision date: February 26, 2014


This data set contains the calculated net ocean-air carbon dioxide (CO2) flux and sea-air CO2 partial pressure (pCO2) difference. The estimates are based on approximately one million measurements made for the pCO2 in surface waters of the global ocean since the International Geophysical Year, 1956-1959. Only the ocean water pCO2 values measured using direct gas-seawater equilibration methods were used. The results represent the climatological distributions under non-El Nino conditions. Since the measurements were made in different years, during which the atmospheric pCO2 was increasing, they were corrected to a single reference year (arbitrarily chosen to be 1995) on the basis of the following assumptions:

There are eight data files with this data set. This includes six compressed (.zip) and two comma-delimited (.csv) files.

Additional Documentation:

This data set is one of the products of the International Satellite Land-Surface Climatology Project, Initiative II (ISLSCP II) data collection which contains 50 global time series data sets for the ten-year period 1986 to 1995. A complete description of the data, it's derivation, acknowledgements, and references provided by the ISLSCP II Data Management Staff is included with this data set as a companion file named 1_air_sea_gas_exchange_doc.pdf.

ISLSCP II is a consistent collection of data sets that were compiled from existing data sources and algorithms, and were designed to satisfy the needs of modelers and investigators of the global carbon, water and energy cycle. The data were acquired from a number of U.S. and international agencies, universities, and institutions. The data and documentation have undergone two peer reviews.

ISLSCP is one of several projects of Global Energy and Water Cycle Experiment (GEWEX) [] and has the lead role in addressing land-atmosphere interactions -- process modeling, data retrieval algorithms, field experiment design and execution, and the development of global data sets.

Data Citation:

Cite this data set as follows:

Takahashi, T., S.C. Sutherland, R.H. Wanninkhof, R.A. Feely, R.F. Weiss, D.W. Chipman, N. Bates, J. Olafsson, C. Sabine, A. Poisson, N. Metzl, B. Tilbrook, Y. Nojiri, and C. Sweeney. 2014. ISLSCP II Air-Sea Carbon Dioxide Gas Exchange. In Hall, Forrest G., G. Collatz, B. Meeson, S. Los, E. Brown de Colstoun, and D. Landis (eds.). ISLSCP Initiative II Collection. Data set. Available on-line [] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA.

File Information:

The archived data sets for ISLSCP II have been organized by categories. This data set is in the Carbon category.

Data Set Spatial Extent: Global

Westernmost Longitude: -180 W

Easternmost Longitude: 180 E

Northernmost Latitude: 90 N

Southernmost Latitude: -90 S

Projection: Geographic

Data Set Spatial Resolution: one degree and five degreees in both latitude and longitude

Data Set Temporal Extent: monthly

Data File Format

There are eight data files with this data set. All files with the .csv file extension were converted from space-separated format (.asc). The  map_1d files are in standard arc/info grid ASCII format (.asc).

 *A value of -999.9 indicates land cells and values of -888.8 indicate cells with sea ice.

NOTE: The 5 x 4-degree files were processed again by: filling in blank pixels along the coastlines using averaging of all the surrounding pixels, then expanding each pixel in a line 5 times, then copying each line 4 times. This preserved the original missing values of -999.9. Additionally, the 1-degree land mask was overlayed on the files, inserting the land (listed as -99.9) at a finer scale than the original 5 x 4-degree data. Thus, there are missing land data listed as -99.9, then additional missing data listed as -999.9. Sea ice is indicated by -888.8.


WARNING: This 1 x 1-degree product is for browse use only. These data files are not interpolated between the original 5 x 4 pixels. Thus the values at specific pixels are not exact. Use this data with caution and always refer to the original tabular data files for specific information.

Please refer to 0_air_sea_gas_readme.txt for additional information on the data file contents and naming conventions.

Data Access:

These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC)  [].

Data Archive Contact Information:

Telephone: +1 (865) 241-3952


Gurney, K.R., R.M. Law, A.S. Denning, P.J. Rayner, D. Baker, P. Bousquet, L. Bruhwiler, Y.H., Chen, P. Ciais, S. Fan, I.Y. Fung, M. Gloor, M. Heimann, K.Higuchi, J. John, T. Maki, S.Maksyutov, K. Masarie, P. Peylin, M.Prather, B.C. Pak, J. Randerson, J. Sarmiento, S.Taguchi, T. Takahashi and C.-W. Yuen, 2001: Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models. Nature, 415, 626-630, Feb. 2002.

Takahashi, T., Sutherland, S. C., Sweeney, C., Poisson, A., Metzl, N., Tillbrook, B., Bates, N., Wanninkhof, R., Feely, R. A., Sabine, C., Olafsson, J. and Nojiri, Y. (2002). Global sea-air CO2 flux based on climatological surface ocean pCO2, and seasonal biological and temperature effects, Deep-Sea Res. II, 49, 1601-1622.