Background Information

The World Ocean Circulation Experiment (WOCE) Hydrographic Program (WHP) was a major component of the World Climate Research Program (WCRP), whose overall goal was to better understand the ocean's role in climate and climatic changes resulting from both natural and anthropogenic causes. The need for this experiment arose from serious concern over the rising atmospheric concentrations of carbon dioxide (CO₂) and their effect on the heat balance of the global atmosphere. The increasing concentrations of these gases may intensify the earth's natural greenhouse effect and alter the global climate in ways that are not well understood. Carbon in the oceans is poorly characterized and unevenly distributed because of complex circulation patterns and biogeochemical cycles. Although total carbon dioxide (TCO₂) was not an official WOCE measurement, a coordinated effort, supported in the United States by the Department of Energy (DOE) and the National Oceanic and Atmospheric Administration (NOAA), was made on WOCE cruises through 1998 to measure the global, spatial, and temporal distributions of TCO₂ and other related parameters. The two primary objectives of this effort were to estimate the meridional transport of inorganic carbon in a manner analogous to the estimates of oceanic heat transport (Bryden and Hall 1980; Brewer et al. 1989; Holfort et al. 1998; Roemmich and Wunsch 1985) and to build a database suitable for carbon-cycle modeling and the estimation of anthropogenic CO₂ increase in the oceans. The CO₂ Survey took advantage of the sampling opportunities provided by the WHP cruises during this period, and the final data set is expected to cover on the order of 23,000 stations. Wallace (2001) has recently reviewed the goals, conduct, and initial findings of the Joint Global Ocean Flux Study (JGOFS)/WOCE Global CO₂ Survey.

This report discusses the carbonate system parameters, TCO₂ and the fugacity of CO₂ (fCO₂), measured aboard the research vessel (R/V) Meteor during Cruise 28, Leg 1, along the WOCE Zonal Section A8. This Section began in Recife, Brazil, on March 29, and ended in Walvis Bay, Namibia, on May 10, 1994 (Fig. 1). This is the concluding section of the four contiguous zonal sections completed in the South Atlantic (A9, A10, A11, and A8) during the WOCE Survey. Scientists from the Brookhaven National Laboratory (BNL) participated in the cruises of these three sections (A9, A10, and A8). The A8 Section cruise continued the tradition whereby personnel from BNL and the CO₂ group at the Institut für Meereskunde Universitat Kiel (IfMK) collaborated to make the CO₂ measurements aboard the R/V Meteor. From this section, the large-scale three-dimensional distribution of temperature, salinity, and chemical constituents, including the carbonate system parameters, can be mapped. Knowledge of these parameters and their initial conditions will allow heat, water, and carbon transports to be determined. An understanding of these transports will contribute to the understanding of processes that are relevant for climate change. This concluding section in the subtropical South Atlantic Ocean is especially relevant to CO₂ transport because it crosses both the Brazil and the Benguela Boundary Currents. An analysis of these data has been published in Holfort et al. (1998).

The work aboard the R/V Meteor was supported by the U.S. DOE under contract DE-ACO₂- 76CH00016. The authors are grateful to the Sonderforschungsbereich 460 at the University of Kiel, which was lead by Dr. F. Schott and funded by the Deutsche Forschungsgemeinschaft, for their support and assistance in completing the written documentation.