Upwelling Systems

Abstract. Eastern Boundary Upwelling Systems (EBUS) are characterized by a high productivity of plankton asso-ciated with large commercial fisheries, thus playing key bi-ological and socio-economical roles. Since they are popu-lated by several physical oceanic structures such as filaments and eddies, which interact with the biological processes, it is a major challenge to study this sub- and mesoscale activ-ity in connection with the chlorophyll distribution. The aim of this work is to make a comparative study of these four upwelling systems focussing on their surface stirring, using the Finite Size Lyapunov Exponents (FSLEs), and their bi-ological activity, based on satellite data. First, the spatial distribution of horizontal mixing is analysed from time aver-ages and from probability density functions of FSLEs, which allow us to divide each areas in two different subsystems