Upwelling events driving ENACW(Eastern North Atlantic CoastalWater) into the Galician western coast rias had been considered typical spring–summer processes, according to the research developed in this area. However, they can also be observed in fall or winter under northerly winds blowing at shelf. Six different upwelling events were analyzed in the Ria of Pontevedra during the wet season (NDJF) from2000 to 2005. These events were characterized bymeans of the zonal Ekman transport (Qx) at four control points in front of the western rias (locally known as Rias Baixas) and thermohaline variables measured at a fixed station in the main mouth of the Ria of Pontevedra. The duration of the upwelling events ranged from27 days (during February andMarch 2002) to 69 days (duringNovember– December 2004 and January 2005). Upwelling events studied in the Ria of Pontevedra from 2000 to 2005 showed the similarity in upwelling features during both seasons (similar wind forcing and upwelled water). Finally, Qx was correlated with the most representative atmospheric patterns in the Northern Hemisphere (EA, NAO, EA/WR, POL and SCA) from1966 to 2005. The winter EA pattern has the most influence on Qx showing an annual evolution with a prevalence of the positive phase from 1976 on. This positive phase is directly correlated with a prevalence of positive values of Qx which are upwelling unfavorable in the Rias Baixas.

This work is a contribution to the Spanish LOICZ coordinate project METRIA supported by the CICYT under projects MAR96-1782, REN2003-04106-C03 and CTM2006-05882-C04-03/MAR and by ‘Xunta de Galicia’ under projects PGIDIT06PXIB383285PR and PGIDIT06PXIB383288PR.

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Peer reviewed