Role of bathymetry in Agulhas Current configuration and behaviour

Abstract

The Agulhas Current forms an important link in the global ocean thermohaline circulation by its role in the inter-ocean exchange of water south of Africa. This process of ring shedding at the current's retroflection is dependent on perturbations to its trajectory that are sensitive to bathymetry. These perturbations may furthermore force the current to intersect shallow regions resulting in substantial changes to its path. A number of other flow characteristics of the system have also been deemed to be influenced by bathymetry. How dependent is Agulhas Current behaviour therefore on the bottom topography? We have used a regional, primitive equation model for initial experimentation. Removing the Agulhas Bank leads to enhanced inter-ocean flux, indicating its importance for inter-ocean exchange. Excising the Agulhas Plateau causes meridional meanders in the Agulhas Return Current to be unlocked from the bathymetry. Smoothing the continental slope weakens the current and substantially increases the direct inter-ocean flux. Copyright 2006 by the American Geophysical Union.