Background Information

The increase in atmospheric carbon dioxide (CO₂) concentrations (as well as in other radiatively active trace gases) because of human activity has produced serious concern regarding the heat balance of the global atmosphere (Moore and Braswell 1994). The increasing concentrations of these gases may intensify the earth's natural greenhouse effect, and force the global climate system in ways that are not well understood. The oceans play a major role in global carbon cycle processes. Carbon in the oceans is unevenly distributed because of complex circulation patterns and biogeochemical cycles, neither of which are completely understood.

To better understand the ocean's role in climate and climatic changes, several large experiments have been conducted in the past, and others are currently under way. The World Ocean Circulation Experiment (WOCE) is a major component of the World Climate Research Program. Although total carbon dioxide (TCO₂) is not an official WOCE measurement, a coordinated effort, supported in the United States by the U.S. Department of Energy (DOE), is being made on WOCE cruises (through 1998) to measure the global, spatial, and temporal distributions of TCO₂ and other carbon-related parameters. The CO₂ survey goals include 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, and preparation of a database suitable for carbon-cycle modeling and the subsequent assessment of the anthropogenic CO₂ increase in the oceans. The CO₂ survey is taking advantage of the sampling opportunities provided by the WOCE cruises during this period. The final data set is expected to cover ~23,000 stations.

This document describes the first effort by chemical oceanographers from Brookhaven National Laboratory (BNL) to make high-quality CO₂ measurements during a 42-day expedition in the South Atlantic Ocean aboard the Research Vessel (R/V) Meteor in the austral summer of 1991. Designated as WOCE Expedition code 06MT15/3, the cruise departed Vitoria, Brazil, on February 10, 1991, and arrived in Pointe-Noire, Congo, on March 23, 1991. The WOCE zonal Section is A9 (Fig. 1).

The CO₂ investigation during R/V Meteor Cruise 15/3 was supported by DOE grant DE-ACO2-76CH00016.