Atlantic South Equatorial Current

Tropical Atlantic waters receive intense solar energy, warming a broad upper layer that can exceed 30 degrees Celsius. This tropical heat contrasts with the polar Atlantic, where surface temperatures may fall below minus 2 degrees Celsius, and with the cold deep ocean far from direct sunlight. The ocean stores this energy over great distances and releases it slowly through currents and contact with the atmosphere.

South Atlantic Central Water originates within the anticyclonic subtropical gyre, while North Atlantic Deep Water flows south beneath the thermocline. That deep current depends on the high surface salinity of the Atlantic and on density changes in high latitudes. Nearer the surface, winds organize a counter-clockwise gyre, exchange with the Indian Ocean adds another origin of water, and the southern gyre's relatively long residence time allows heat and dissolved substances to spread through the basin.

The equatorial upper ocean is thus a reservoir rather than a fixed sheet of warm water. Its temperature and movement influence tropical rainfall, regional climates, and the physical routes available to mariners. Winds and currents can spread that stored heat far beyond the latitude where it entered the sea.