This project is a two-year investigation into the dynamics and processes of deep water mass formation in the western Weddell Sea, combining physical and chemical oceanographic techniques to produce a coherent picture of the importance of this unique region to the structure of the world ocean. In the global context, this area is a major water mass modification site, involving open ocean convective events, the continental margin, and the ice cover. At this time the various water types that combine to form Weddell Sea Deep Water and Antarctic Bottom Water, and the conditions under which these water masses form, are not known well enough to establish direct physical links and volumetric budgets. It is suspected that the outflow from the Weddell Sea is restricted to quite narrow boundary currents flowing near the base of the continental shelf, and consequently may be observed with conventional current meter moorings from the shelf into the deep ocean. Two oceanographic expeditions to the western Weddell Sea are planned as part of this study: the first in the 1990/91, and the second in 1991/92. The objectives will be to measure the flow of newly-formed bottom water and to explore the sinking process of near-surface waters in the open ocean to see how these affect the deep water flows. In the first year the primary objective will be to set out an array of eight current meters in the bottom water core, while a secondary objective will be to grapple for an existing array that was set out in early 1988 but could not be recovered in 1989 because Antarctic Program ship resources had to be diverted to deal with the oil spill at Palmer Station. In the second year the array will be retrieved. Hydrographic cruises in order to define the upper ocean temperatures and salinity structure in the outflow region where unusually large step structures have been found in the past. A chemistry program consistent with the objectives of the World Ocean Circulation Experiment (WOCE) and presently planned experiments in the South Atlantic Ocean, will be integrated into the cruises carried out under this project.
