Agulhas Current

Along with direct branch currents, this leakage takes place in surface water filaments, and Agulhas Eddies.

This heat flux is believed to contribute to the high rate of evaporation in the South Atlantic, a key mechanism in the Meridional Overturning Circulation.

Due to surface dissipation, these filaments are not believed to significantly contribute to inter-basin heat flux.

[3] Where the Agulhas turns back on itself the loop of the retroflection pinches off periodically, releasing an eddy into the South Atlantic Gyre.

These anticyclonic warm core rings are estimated to have a transport of 3-9 Sv each, in total injecting salt at a rate of 2.5

Franzese et al. 2009 analysed cores in the South Atlantic deposited during the Last Glacial Maximum (LGM, 20 000 years ago), and concluded that the Agulhas leakage was significantly reduced.

Some 30 larger ships were severely damaged or sunk by rogue waves along the South African east-coast between 1981 and 1991.

[15] Below 1,800 m (5,900 ft) a separate layer of the undercurrent can be distinguished: the more coherent North Atlantic Deep Water (NADW) which transports an average of 2.3±3.0 Sv.

[15] NADW rounds the southern tip of Africa after which the major part (9 Sv) flow eastward and a smaller part (2 Sv) northward through the Agulhas Undercurrent and into the Natal Valley (the basin between South Africa and the Mocambique Plateau); remnants of NADW has been observed in the Mozambique Basin and Channel.

Both of these factors result in the area being one of enhanced primary productivity as compared to the surrounding waters.

[17] Warm core rings are known to have lower primary productivity than surrounding cold waters.

The size of phytoplankton in Agulhas Rings tends to be smaller than in the surrounding water (around 20 μm in diameter).

[17] Agulhas Rings have also been observed as removing larval and juvenile fish from the continental shelf.

This removal of young fish can result in a reduced anchovy catch in the Benguela system if a ring passes through the fishery.

The courses of the warm Agulhas current (red) along the east coast of South Africa, and the cold Benguela current (blue) along the west coast. The Agulhas Current is formed by the confluence of the warm Mozambique and East Madagascar Currents , which meet south-west of Madagascar (not shown in the diagram). The cold Benguela Current originates from upwelling of water from the cold depths of the Atlantic Ocean against the west coast of the continent. The two currents do not "meet" anywhere along the south coast of Africa.
Agulhas rings are peeled off the Agulhas Current in the Agulhas Basin where it retroflects back into the Indian Ocean.
Mean chlorophyll-a concentration map of the Agulhas Current for 2009. Note the high productivity water in the Agulhas Retroflection.