Circulation patterns in the Delagoa Bight, Mozambique, and the influence of deep ocean eddies

Abstract

An investigation of the circulation patterns and thermohaline structures in the Delagoa Bight, Mozambique, was undertaken during May 2004, August 2004, April 2005, and April 2006, using hydrographic surveys, surface drifters and satellite imagery. Hydrographic and satellite data during May 2004 illustrated a cyclonic eddy centred at 26° S, 34.25° E in the Bight. A surface drifter remained trapped in this eddy for six weeks between 8 May and 20 June 2004 before moving southward in the Agulhas Current. During August 2004, the core of a cyclonic eddy was located south of the Bight, while no cyclonic eddy was observed during April 2005 or in April 2006. The Delagoa Bight eddy appeared to be more transient than previously thought. Important observations were the recurrent northward current (25–30 cm s^–1) occurring subsurface on the shelf, and the prominence of cooler upwelled water at various locations due to the interaction of passing eddies with the bottom topography of the Bight.

Keywords: coastal countercurrent, cyclonic lee eddy, Delagoa Bight, upwelling

African Journal of Marine Science 2010, 32(3): 553–562