Spatiotemporal evolution of upwelling regime along the western coast of the Iberian Peninsula

The spatial and temporal variability of upwelling regime along the western coast of the Iberian Peninsula (IP) has been analyzed by means of two different but complementary databases: QuikSCAT satellite database, which is available from mid‐1999 with a high spatial resolution (0.25° × 0.25°); and Pacific Fisheries Environmental Laboratory (PFEL) database, with a coarser spatial resolution (1° × 1°) but extending back to 1967. The combined use of both databases allows determination of the spatial variability of Ekman transport and pumping, and identification of temporal trends in upwelling signal. Upwelling‐favorable conditions are observed during spring and summer. Apart from this well‐known seasonality on upwelling regime along the western coast of the IP, some other features have been identified: (1) Upwelling occurs simultaneously along the entire western coast of the IP, but is undoubtedly more complex closer to particular features of the shoreline. (2) Positive Ekman pumping is more intense near Capes Sao Vicente and Rocha during spring‐summer and near Cape Finisterre all over the year. (3) More favorable upwelling conditions have been observed in February and November during the last decade. This result is corroborated by Sea Level Pressure composites, which show the existence of abnormally high pressures close to the IP during the last decade compared to the historical records (1948–2006). (4) The decadal variability of UI is higher in autumn‐winter than in spring‐summer. (5) Monthly upwelling trends indicate a weakening in upwelling intensity during most of the year with the exception of February, June, and July.