Suppression of Bottom Water Formation in the Southeastern Weddell Sea

The lack of bottom water formation in the southeastern Weddell Sea is investigated on the basis of CTD, current meter, and oxygen isotope data obtained in 1986 during the Winter Weddell Sea Project and in summer 1989 during the European Polarstern Study. The principal underlying factor in suppressing the formation of bottom water is the narrow continental shelf in the region. This leads to two consequences not obtained in the western Weddell Sea: (1) the coastal polynya is able to extend out well over deep water and over the swift-moving Antarctic Coastal Current, which acts to inhibit the accumulation of salt released by surface freezing in the polynya; and (2) the upper portions of Warm Deep Water come into close proximity with the glacial ice shelf floating above the continental shelf, thus providing heat for melting at the base of the ice shelf. Budgets for heat and salt derived from the winter data, along with measurements of deltaO-18, indicate that this melting occurs at rates more than sufficient to compensate the combined effects of brine released by freezing in the polynya and the upward flux of salt from the Warm Deep Water. As a result, the Eastern Shelf Water cannot acquire the salt concentrations needed for the formation of bottom water.