A system of ocean currents forming a closed loop that transports cold water from the edge of the sea ice in the North Atlantic (see thermohaline circulation). The water flows along the ocean floor to the Southern Ocean, then eastward and later northward, crossing the equator in the Indian and Pacific Oceans where it rises to about 1000 m below the surface. Moving westward, it passes to the east of Madagascar, rounds the Cape of Good Hope, and flows northward through the Atlantic, completing the loop. See illustration.
Subjects: Ecology and Conservation.