This exercise explores the dynamics of the upper ocean, where the water particles are directly exposed to the action of the wind. The depth range over which the wind exerts a direct influence on water movement through frictional drag on the water particles is known as the Ekman layer.
The exercise begins with a detailed look at the structure of currents in the Ekman layer under conditions of unidiv mixing. It then moves on to study the conditions under which movement in the Ekman layer leads to vertical water movement (upwelling and downwelling) in coastal regions and at the equator. The exercise concludes by evaluating Ekman layer transports for a zonal section around Antarctica and by discussing the significance and implications of meridional Ekman layer transports across entire ocean basins.
To understand the dynamics of the Ekman layer it is best to begin with a situation that excludes all processes not relevant to the problem. The Ekman layer is defined as the layer which is directly influenced by the wind, so the wind is obviously an important element of Ekman layer dynamics. Which other force, or forces, do we have to include to obtain the basic balance of forces that determines currents in the Ekman layer?