Comment on the South Atlantic’s Role in the Global Circulation

Abstract

The role of the South Atlantic in the global climate system, specifically as it concerns the North Atlantic Deep Water driven thermohaline meridional overturning cell, has drawn much attention in recent years. I propose that the configuration of the continents bounding the South Atlantic, specifically the contrast in the southern extreme of South America and Africa relative to the maximum westerlies wind, allow the development of a salty Atlantic Ocean, preconditioning the region for production of North Atlantic Deep Water, whose positive feedbacks further energizes the process. Much of the low salinity upper layer water carried by the South Pacific Current towards the coast of Chile, turns northward into the subtropical South Pacific as the Peru Current. Pacific surface water that does flow through the Drake Passage tends to transverse the South Atlantic, picking up more freshwater enroute drawn from the evaporative regime of the South Atlantic subtropics, into the Indian Ocean. Only a small component of the South Atlantic Current turns northward into the Benguela Current. Warm, saline Indian Ocean thermocline water can slip along the southern rim of Africa into the South Atlantic to further increase Atlantic salinity.