Atlantic South Current

The South Atlantic communicates with the Indian Ocean in the southeast and toward the Pacific in the southwest, while also joining the circulation around Antarctica. Vasco da Gama demonstrated the Indian Ocean connection in 1498 by sailing around the Cape of Good Hope. The crossing of Pedro Álvares Cabral’s India-bound fleet to Brazil in 1500 showed that reaching the intended ocean could depend on the South Atlantic Gyre rather than a straight course.

That gyre is anti-cyclonic and turns counter-clockwise. South Atlantic Central Water is produced within it. Antarctic Intermediate Water originates in the upper circumpolar region near the Drake Passage and the Falkland Islands, while both this water and the subtropical system receive some contribution from the Indian Ocean. North Atlantic Deep Water flows south beneath the subtropical thermocline. The South Atlantic therefore connects its own continental shores to distant ocean basins through surface, intermediate and deep layers.

The geological connections are just as important. West Gondwana broke apart in the Early Cretaceous to form the South Atlantic. The Mid-Atlantic Ridge then divides the basin lengthwise, with transform faults and secondary ridges breaking it into separate deep basins. The Walvis Ridge and Rio Grande Rise obstruct currents, and the opening of the Drake Passage established a deep southern gateway. Winds, moving water and submerged barriers together make this a junction between the Atlantic, Indian and circumpolar oceans.