Oceanographic variability in the northern shelf of the Iberian Peninsula, 1990-1999

Atmospheric and oceanographic variability off the northern Iberian Peninsula in the 1990s is described from climatological databases and Spanish hydrographic surveys. The wind regime during the dccade can be divided into two principal periods. In the first, northerly (upwelling favourable) winds are prom inent, while in the second, southwesterly winds dom inate, resulting in diminished upwelling, an increase in sea surface tem peratures and the occurrence of the winter polew ard current. In the sub­surface waters during summer, a w arm ing trend through the 1990s of between 0.02 and 0.05°C year^-1 is found, with the maximum am plitude between 150 and 200 m. The w arm est year was 1998. Salinity also varied during the decade, with higher salinities generally reflecting an increase in the poleward current and low salinities indicating advection from the inner Bay o f Biscay. In 1995/1996 and 1997/1998, a strong winter surface Poleward Current carrying warm, salty water was present along the Portu­guese coast and reached the southern Bay o f Biscay. It contributed significantly to the heat content in the upper 500 m of the w ater column. The intensification o f the Poleward Current is associated with increased onshore E km an transport during autum n in western Galicia. Sea level variability also reflects wind changes with stron­ger southwesterly winds resulting in higher levels. Mean sea level increased from 1993 to 1997, giving a somewhat greater increasing trend for the last decade com pared to the long-term over the past 55 years.

Article from Marine Science Symposia Vol. 219 - "Hydrobiological variability in the ICES Area, 1990-1999", symposium held in Edinburgh, 8-10 August 2001. To access  the remaining articles please click on the keyword "MSS Vol. 219".