Circulation in the western Weddell Sea is dominated by a northward flowing current. This northward current is the western section of a primarily wind-driven, cyclonic gyre called the Weddell Gyre. This northward flow serves as the primary force of departure of water from the Weddell Sea, a major site of ocean water modification and deep water formation, to the remainder of the World Ocean. The Weddell Gyre is a cold, low salinity surface layer separated by a thin, weak pycnocline from a thick layer of relatively warm and salty water referred to as Weddell Deep Water (WDW), and a cold bottom layer.