What is the Ekman spiral? Explain why Ekman transport occurs

Question

What will be an ideal response?

Answer 1

Due to friction between wind and the water surface, some of the kinetic energy of the air is transferred to the top layer of the water. As that layer moves, it drags along the water just below it, which in turn drags along the water just below that, and so on. The water can be thought to move as many thin, coupled layers, and kinetic energy is transferred down the water column. However, as the energy is transferred downward, friction causes some of the energy to be dissipated in the form of heat, so each level moves more slowly than the level above. At some depth below the surface, the effects of the wind-induced movement disappear. However, as each layer moves, it is again subject to the Coriolis Effect. Once a layer starts to move, the water is deflected to the right of the path of the layer above (or the wind path, for the surface layer). This movement is to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The deeper below the surface, the farther each layer is deflected to the right or left of the surface layer, producing a spiraling effect known as the Ekman spiral. When the movements of all the individual layers of water in the spiral are added, the net direction of transport within the water column is at a right angle (90°) to the wind direction. This net movement of water is referred to as Ekman transport.