Dependance of upwelling related circulation on wind forcing and stratification over the Portugal northern shelf

Abstract

Current measurements over the northern Portuguese shelf during May-September 1987 are used together with coastal wind data to infer the shelf circulation associated with upwelling events. The time response of the ocean to the atmospheric forcing was found to be close to 1 day. A surface equatorward jet appeared at a coastal position and, as the wind event persisted, extended vertically to the bottom and consistently moved offshore, its outermost position being dependant on the event duration. Strength and persistence of upwelling fuvorable winds seem to have been. much more important than stratification in determining the depth penetration of the coastal jet and the cross-shelf circulation pattern. Three-dimensional effects appeared, on the other hand, to be non negligible