Determination of the impact of coastal wind variability and associated pressure gradients in the Humboldt Current System off Chile.

Determination of the impact of coastal wind variability and associated pressure gradients (mid-latitude frontal disturbances, coastal lows and other atmospheric waves) on the temporal and spatial distribution of upwelling events in the Humbolct Current System off Chile. Wind driven coastal upwelling is a prevalent phenomenom in the HCS off Chile. Equatorward winds along the coast not only induce the classical net offshore surface Ekman transport but they also promote active mixing in the surface layer. Wind stress differentials along the coast force shelf waves that may interact with remotely-forced coastal-trapped waves (CTW) traveling poleward along the coast while wind-stress differentials in a cross-shore direction can enhance upwelling through cyclonic wind-stress curl. The upwelling band off Chile is exceptionally narrow compared with other eastern boundary current systems, possibly under the influence of the offshore circulation regime. Upwelling is intensified around capes protruding to the west, and usally involve water from the poleward undercurrent.