A summary of coastal upwelling dynamics. Left: plan view; right: vertical section (northern hemisphere). The wind blows parallel to the coast with the coastline on its left (right) north (south) of the equator.

The surface Ekman layer transport is directed 90° to the right (left) of the wind direction south (north) of the equator, producing offshore surface water movement in both hemispheres. This lowers the sea surface near the coast. The result is a pressure gradient normal to the shore, which drives a geostrophic current along the coast, in the same direction as the wind.

The net water movement is the result of both the wind-driven Ekman flow and the geostrophic flow. It is directed away from the coast near the surface, parallel to the coast at mid-depth and at an angle towards the coast above the bottom.

Adapted from Tomczak and Godfrey (1994)

© 1996 M. Tomczak

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