Atlantic South Equatorial Current

The southern tropical current region links the equatorial Atlantic to the subtropical and higher-latitude ocean. Its upper waters participate in the anticyclonic South Atlantic Gyre, a warm counter-clockwise system that dominates the basin. South Atlantic Central Water forms within this gyre, receiving some contribution from the Indian Ocean and spreading the properties of the subtropical surface ocean into neighboring regions.

Far below, North Atlantic Deep Water continues south beneath the thermocline. This deep flow carries cold, dense water formed in the north across the equator and through the southern basin, where it encounters Antarctic water masses and seabed ridges. The surface and deep currents do not carry the same water in the same direction, giving the South Atlantic a strongly layered circulation. Wind-driven upwelling and exchange with the Indian Ocean further modify the upper ocean.

The result is a basin that redistributes heat and salt between hemispheres across a wide range of depths. Its tropical waters are connected to cold northern origins and to the Southern Ocean even when the visible surface suggests a uniform warm expanse. This arrangement makes the South Atlantic a key passage for water moving between hemispheres.