HYDROGRAPHIC CONDITIONS ASSOCIATED WITH THE RELAXATION OF AN UPWELLING EVENT OFF THE GALICIAN COAST (NW SPAIN)

During the GALICIA-XI cruise froin May 10 to May 14, 1991 the relaxati on of a previous strong upwelling event took place along the Galician coast caused by a shift in the position of the Azores High. The coldes t temperatures and highest nitrate levels were found near the coast co rresponding to the advection of subsurface waters, particularly of Eas tern North Atlantic Water (ENAW). On the basis of thermohaline propert ies, ENAW of polar (ENAW(p)) and tropical (ENAW(t)) origin are disting uished. The highest salinity values found correspond to a saline wedge of ENAW(t) located of the west coast of Galicia. The relaxation of up welling produced a shoreward migration of surface water from oceanic s tations which caine into contact with upwelled Eastern North Atlantic Water from the coastal stations to form a convergence from 28 km off t he coast. Meanwhile, the saline wedge displaced towards both the north and the shore which is favored by the compression of the upwelling sy stem to a narrow coastal strip outwardly limited by the convergence zo ne.