The circulation and upwelling processes that control the phytoplankton distribution in the Alboran Sea (western Mediterranean) are examined from a climatological perspective for the first time. To characterize the annual cycle of the near-surface phytoplankton patterns, we analyze the monthly distributions of pigments from the Coastal Zone Color Scanner (CZCS). Two regimes occur: a fall-to-winter bloom (November-March) and a non-bloom period (May-September). These regimes differentiate the basin from other parts of the western Mediterranean, where a significant spring bloom occurs. The newest ocean color data sets available today from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and the Ocean Color and Temperature Scanner (OCTS) fall within this annual progression. The combined interaction of seasonal stratification, coastal and gyre-induced upwelling, and horizontal advection control the near-surface pigment distribution in Alboran, while light availability does not determine the seasonal cycle of pigments. ¿ 1999 American Geophysical Union