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 da ta obtained in 1986 during the Winter Weddell Sea Project and in summe r 1989 during the European Polarstern Study. The principal underlying factor in suppressing the formation of bottom water is the narrow cont inental shelf in the region. This leads to two consequences not obtain ed in the western Weddell Sea: (1) the coastal polynya is able to exte nd out well over deep water and over the swift-moving Antarctic Coasta l Current, which acts to inhibit the accumulation of salt released by surface freezing in the polynya; and (2) the upper portions of Warm De ep Water come into close proximity with the glacial ice shelf floating above the continental shelf, thus providing heat for melting at the b ase of the ice shelf. Budgets for heat and salt derived from the winte r data, along with measurements of deltaO-18, indicate that this melti ng occurs at rates more than sufficient to compensate the combined eff ects 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 bo ttom water.