Background Information

The World Ocean plays a dynamic role in the Earth's climate: it captures heat from the sun, transports it, and releases it thousands of miles away. These oceanic-solar-atmospheric interactions affect winds, rainfall patterns, and temperatures on a global scale. The oceans also play a major role in global carbon-cycle processes. Carbon is unevenly distributed in the oceans because of complex circulation patterns and biogeochemical cycles. The oceans are estimated to hold 38,000 gigatons of carbon, 50 times more than that in the atmosphere and 20 times more than that in plants, animals, and soil. If only 2% of the carbon stored in the oceans were released, the level of atmospheric carbon dioxide (CO2) would double. Every year, the amount of CO2 exchanged across the sea surface is more than 15 times that produced by the burning of fossil fuels, deforestation, and other human activities (Williams 1990).

To better understand the ocean's role in climate and climatic changes, several large experiments have been conducted, and others are under way. The largest oceanographic experiment ever attempted is the World Ocean Circulation Experiment (WOCE). A major component of the World Climate Research Programme (WCRP), WOCE brings together the expertise of scientists and technicians from more than 30 nations. In the United States, WOCE is supported by the federal government under the Global Change Research Program. The multiagency U.S. effort is led by the National Science Foundation and is supported by major contributions from the National Oceanic and Atmospheric Administration (NOAA), the U.S. Department of Energy (DOE), the Office of Naval Research, and the National Aeronautics and Space Administration. Although total carbon dioxide (TCO2) is not an official WOCE measurement, a coordinated effort, supported in the United States by DOE, was made on WOCE cruises to measure the global distributions of TCO2 and other carbon-related parameters [total alkalinity (TALK), partial pressure of CO2 (pCO2), and pH]. The goal of the DOE's CO2 survey includes estimation of the meridional transport of inorganic carbon in a manner analogous to the oceanic heat transport (Bryden and Hall 1980; Brewer et al. 1989; Roemmich and Wunsch 1985), evaluation of the exchange of CO2 between the atmosphere and the ocean, preparation of a database suitable for carbon-cycle modeling, and subsequent assessment of anthropogenic CO2 in the oceans. The final data set is expected to cover ~23,000 stations.

This report presents CO2-related measurements obtained during the 37-days of the Research Vessel (R/V) Thomas G. Thompson expedition along the WOCE meridional Section P10 (Fig. 1).

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