Lundi 3 Novembre - Response of the Benguela upwelling system to spatial inhomogeneities of the wind forcing
Tim Junker, Post-doc at IOW, Leibniz-Institut für Ostseeforschung Warnemünde (Germany)
Response of the Benguela upwelling system to spatial inhomogeneities of the wind forcing
The Benguela upwelling system (BUS) is among the major eastern boundary upwelling ecosystems in the world oceans, and the wind forcing in that region is of particular importance. For a few years now, remotely sensed data has revealed very persistent pattern in the wind stress along the southwest African coast including spatial inhomogeneities of a few hundred kilometers. The present study aims at understanding the currents response in the BUS to spatial and temporal variations of the wind forcing by combining analytical and numerical modeling with field observations. We focus hereby on two major aspects of the circulation in the BUS: the cross-shore advection off Cape Frio and the seasonality of the meridional transport along the southwest African coast. We present evidence that the dynamical reason for the partly westward bending of the Angola Current near Cape Frio is related to the strong spatial inhomogeneity of the wind forcing. Moreover, we show that there is a pronounced relationship between the meridional transport and the wind stress curl on a seasonal time scale in the northern BUS. The curl of the wind stress may support a southward advection of tropical waters into the upwelling system.