This project is a renewal of an investigation into the large-scale and mesoscale dynamics of the eastern Weddell Gyre, dealing with the analysis of a data set obtained on an extensive cruise to the Weddell Sea in the austral winter 1989 in a cooperative program with the West German Polar Institute, and the USSR Arctic and Antarctic Research Institute. The cruise generated a substantial body of data on the structure of the upper ocean in winter to complement the existing body of data on summer conditions. Oceanographically the Weddell Gyre acts as a primary area of deep water mass formation and ocean ventilation. Maud Rise, a seamount in the eastern Weddell Sea, introduces topographically determined dynamics which appear to control the occasional formation of the Weddell Polynya, a large area of open water where normally winter sea ice is found. An understanding of these effects is necessary to determine the nature of such important phenomena as water mass modification, maintenance of fronts, deep ocean ventilation, sea ice distribution, and climate modification. This renewal phase of the project includes the completion of data processing, and the synthesis of the data set which will provide a basic description of the Southern Ocean thermohaline and chemical stratification under the sea ice cover from its outer fringes to the coast of Antarctica. Several tasks will be undertaken: the mapping and description of the full water column winter stratification of the Weddell Gyre, the study of the entrainment of deep water into the winter mixed layer in various sub-regions of the gyre, and the study of the oceanography associated with Maud Rise, specifically the initiating of strong upwelling and its effect in producing the periodically forming Weddell Polynya.
