Southern Ocean overturning circulation is the southern half of a global thermohaline circulation, which connects different water basins across the global ocean. Its better-known northern counterpart is the Atlantic meridional overturning circulation (AMOC). This circulation operates when certain currents send warm, oxygenated, nutrient-poor water into the deep ocean (downwelling), while the cold, oxygen-limited, nutrient-rich water travels upwards at specific points. Thermohaline circulation transports not only massive volumes of warm and cold water across the planet, but also dissolved oxygen, dissolved organic carbon and other nutrients such as iron. Thus, both halves of the circulation have a great effect on Earth's energy budget and oceanic carbon cycle, and so play an essential role in the Earth's climate system.
A schematic overview of the Southern Ocean overturning circulation. The arrows point in the direction of the water movement. The lower cell of the circulation is depicted by the upwelling arrows south of the Antarctic Circumpolar Current (ACC) and the formation of Antarctic Bottom Water beneath the sea ice of Antarctica due to buoyancy loss. The upper cell is depicted by the upwelling arrows north of the ACC and the formation of lighter Antarctic Intermediate water due to buoyancy gain north of the ACC.
3D representation of North Atlantic Deep Water upwelling in the Southern Ocean basin, which closes the connection between the Atlantic and Southern circulation, and takes place along the defined pathways with limited mixing.
The role of seasonal meltwater from the Antarctic ice sheet in driving the lower-cell circulation.
Southern Ocean
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The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the world ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of 20,327,000 km2 (7,848,000 sq mi), it is regarded as the second-smallest of the five principal oceanic divisions: smaller than the Pacific, Atlantic, and Indian oceans but larger than the Arctic Ocean.
1928 delineation
1937 delineation
James Weddell's second expedition in 1823, depicting the brig Jane and the cutter Beaufroy
Famous official portrait of Captain James Cook who proved that waters encompassed the southern latitudes of the globe. "He holds his own chart of the Southern Ocean on the table and his right hand points to the east coast of Australia on it."