The principal subsurface oceanic circulation system. It is a thermohaline circulation, primarily driven by the intense evaporation and cooling that occurs in the North Atlantic. This creates a downwelling of dense, saline bottom water, which flows south to Antarctica, where there is a very significant contribution of Antarctic Bottom Water from the major source in the Weddell Sea. From here the flow continues through the Indian and Pacific Oceans, before eventually rising and flowing northwards in the Atlantic to complete the circulation.
Subjects: Meteorology and Climatology.