Deep and Bottom Waters in the Eastern Scotia Sea: Rapid Changes in Properties and Circulation

Abstract

Abstract Two meridional hydrographic transects (in 1995 and 1999) across the eastern Scotia Sea are used to investigate variability in the deep and bottom waters between the South Scotia Ridge and South Georgia. There is a significant warming of the warm deep water (WDW) south of the southern boundary of the Antarctic Circumpolar Current (ACC); waters are approximately 0.1°–0.2°C warmer in 1999 than 1995. This is due mainly to raised WDW potential temperatures in the Weddell Sea being fed through to the Scotia Sea as the WDW flows northeastward in the Weddell Gyre. There is a warming of the Weddell Sea Deep Water (WSDW) of approximately 0.05°C across the whole extent of the section, and an accompanying change in salinity that maintains the potential temperature–salinity relationship. This is caused by variability in the properties of the water overflowing the South Scotia Ridge, rather than enhanced outflow of the bottom layer of the Scotia Sea or movements of the ACC fronts, and may be related to changes...