Ekman transport

Ekman Transport is the net motion of fluid as the result of a balance between Coriolis and turbulent drag forces. In the picture above, the wind blowing North creates a surface stress and a resulting Ekman spiral is found below it in the column of water.

Ekman transport, named for Vagn Walfrid Ekman, is the natural process by which wind causes movement of water near the ocean surface. Each layer of water in the ocean drags with it the layer beneath. Thus the movement of each layer of water is affected by the movement of the layer above (or below in the case of a frictional bottom boundary layer). If the friction between layers is uniform with depth the motion of the water is described by the Ekman spiral. In Ekman transport the force of the wind is balanced by the Coriolis effect which acts perpendicular to the motion of the water. The ocean's surface current is to be the right of direction of surface wind in the Northern Hemisphere, and to the left in the Southern Hemisphere. The net movement of ocean water due to the wind is perpendicular to the wind (again to the right of the wind in the Northern Hemisphere and to the left in the Southern Hemisphere).

Examples

If the transport of water is away from a coast, it creates an upwelling of deep, nutrient-rich sea water. This has the effect of creating good fishing regions along coasts where this phenomenon occurs.

External links

• What is Ekman transport ?
• A figure explaining Ekman transport