Background Information

The World Ocean Circulation Experiment (WOCE) Hydrographic Program (WHP) is a major component of the World Climate Research Programme (WCRP). The overall goal of the WCRP is to better understand the role of the ocean 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 concentration of carbon dioxide (CO₂) and its effect on the heat balance of the global atmosphere. The increasing concentration of this gas may intensify the earth's natural greenhouse effect and alter the global climate in ways that are not well understood. The complex, and poorly understood, circulation patterns and biogeochemical cycles of the ocean yield a complex and uneven distribution of CO₂. Although total CO₂ (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 as well as other related parameters. Goals of the survey are to estimate the meridional transport of inorganic carbon in a manner analogous to the oceanic heat transport estimates (Bryden and Hall 1980; Brewer et al. 1989; Roemmich and Wunsch 1985) and to build a database suitable for carbon-cycle modeling and the subsequent estimation of anthropogenic CO₂ increase in the oceans. The CO₂ survey is taking advantage of the sampling opportunities provided by the WHP cruises during this period. The final data set is expected to cover ~23,000 stations.

This report discusses the results of the research vessel (R/V) Meteor Cruise 22/5 along the WOCE zonal section A10 (along ~30° S) ( Fig. 1). The expedition started in Rio de Janeiro, Brazil, on December 27, 1992, and ended in Capetown, South Africa, on January 31, 1993. This section is one of four zonal sections (A8, A9, A10, and A11) completed in the South Atlantic Ocean during the WOCE survey. The large-scale three-dimensional distribution of temperature, salinity, and chemical constituents, including the carbonate system parameters, will be plotted using the data from these sections. Knowledge of these parameters and their initial conditions will enable researchers to determine heat and water transport as well as carbon transport. An understanding of this transport will contribute to the understanding of processes that are relevant to climate change. This section in the South Atlantic subtropical gyre is especially relevant to understanding CO₂ transport because it crosses both the Brazil and the Benguela boundary currents.

This data documentation is the result of the cooperative efforts of chemical oceanographers from Brookhaven National Laboratory (BNL), U.S.A; Baltic Sea Research Institute [Institut für Ostseeforschung (IOW)], Germany; and the Institute for Marine Sciences of University of Kiel [Institut für Meereskunde Kiel (IfMK)], Germany.