Deep and bottom water of the Bransfield Strait eastern and central basins

Temperature, salinity, oxygen, and chlorofluorocarbon (CFC) data obtained i n September 1997 define the water types ventilating the deep eastern and ce ntral basins of the Bransfield Strait. These water types are observed adjac ent to Joinville Island and are clearly derived from the Weddell Sea. The e astern basin bottom water characteristics closely match that of the bottom water at 310 dbar depth similar to 50 km east of Joinville Island. The east ern basin bottom water is a simple mixture of low-salinity freezing point s helf water (65%) and relatively warm saline Weddell Deep Water (35%), with a CFC-113: CFC-11 ratio age of 8.5 years. The eastern basin bottom water sh ares a common origin with a weak salinity minimum observed at 1000 dbar wit hin the central basin, though overflow from the central basin to the easter n basin floor may also occur. The bottom water within the central basin is colder and saltier with higher concentrations of oxygen and CFC-11 than tha t of the eastern basin. The central basin bottom water with a CFC ratio age of 7.5 years is composed of same Weddell water types that form the eastern basin bottom water plus a large contribution of high-salinity freezing poi nt shelf water of the characteristics of water observed 10 km northeast of joinville Island and a small amount of Pacific pycnocline water. The compon ents (and their percentage) are Weddell Deep Water (11%), low-salinity shel f (24%), high-salinity shelf (60%), to Pacific pycnocline (5%).