Observations of the inter-ocean exchange around South Africa



There is growing evidence that the interocean exchange south of Africa is an important link in the global overturning circulation of the ocean, the so-called ocean conveyer belt. At this location, warm and salty Indian Ocean waters enter the South Atlantic and are pulled by currents that eventually reach the North Atlantic, where water cools and sinks.

A major contributor to the exchange is the frequent shedding of ring eddies from the termination of the Agulhas Current south of the tip of Africa.This shedding is controlled by developments far upstream in the Indian Ocean, and variations in this ‘Agulhas Leakage’ can lead to changes in the rate and stability of the Atlantic overturning, with possible associated global climate variations [Weijer et al., 1999]. Regional climate variations in the tropical and subtropical Indian Ocean are known to affect the whole system of the Agulhas Current, including the interocean exchanges. This article reports on some of the seminal results of ongoing multinational, multidisciplinary projects that explore these issues.