Physical Aspects and Biological Consequences of Ghanaian Coastal Upwelling
Results of recent research on the physical and biological aspects of the Ghanaian coastal upwelling are presented. This upwelling is unusual in that its occurrence and intensity do not correlate with variations in the local wind. During the upwelling the strong stratification over the shelf breaks down as cold saline water comes to the surface, initiating a period of high biological productivity. Surf ace current records and hydrographic sections taken in 1974 both suggest an offshore displacement in the surface layer, but this and the change in the sea level do not correlate with the surface wind. The upwelling does not appear to be driven by changes in the circulation on the shelf. The observation of low frequency waves over the shelf and on the equator in the Gulf of Guinea suggest that they may provide a nonlocal driving mechanism for this coastal upwelling.