A set of weekly-composite SeaWiFS (Sea-viewing Wide Field of view Sensor) imagery (from 1998 to 2004) has been used to asses the temporal and spatial variability of the surface chlorophyll distribution in the Northwestern Alboran Sea. Empirical Orthogonal Function (EOF) analysis of the images series shows the existence of three different regions in which surface chlorophyll presents a homogeneous temporal behavior in the neighborhood of the Strait of Gibraltar.The temporal patterns of surface chlorophyll concentrations in each region have been characterized by studying the role of several forcing factors, mainly the zonal component of the wind field.The first identified region occupies the coastal area in front of Estepona and Málaga and shows the highest chlorophyll concentration in the entire region of study in absence of easterly winds. A second region is located far offshore, in the zone usually occupied by the Atlantic jet entering the Alboran Sea, showing high concentrations of chlorophyll when the easterlies blow. Finally, a third region has been situated in the normal location of the Western Alboran Gyre (WAG).The zonal wind field arises as a main forcing function in the modulation of the intensity and location of the upwelling processes in the area, while the entrance of the Atlantic jet seems to be the main agent feeding of all these processes.