Coastal upwelling: a time-varying view

Abstract

The irregular but accelerating development in the understanding of the physical processes involved in coastal upwelling is reviewed. From early ideas of two-dimensional time-invariant upwelling under idealised winds to present-day concepts of a three-dimensional, constantly changing system forced heterogeneously, advances have followed in the wake of increasingly sophisticated observational and computational techniques that have provided unprecedented views of the ocean. Our present understanding is explored through case studies of surface forcing, physical processes near shore, upwelling and relaxation in the upper layers, horizontal and vertical exchanges, cold filaments and long term trends. The wider implications of our improved knowledge of the physical processes for the upwelling ecosystems are investigated in view of significant shortcomings that remain in our observational, analytical and predictive capabilities