Ekman spiral A theoretical model which explains the currents that would result from a steady wind blowing over an ocean of unlimited depth and extent, which was proposed by the Swedish oceanographer Vagn Walfrid Ekman (1874–1954). In the northern hemisphere, the surface layer of the water would flow at an angle of 45° to the right of the wind direction. Water at increasing depths would flow in directions more to the right, until, at a depth known as the Ekman depth, the water would move in a direction opposite to that of the wind. The Ekman depth varies with latitude but is of the order of 100 m in mid-latitudes. The velocity of the water flow decreases with depth throughout the spiral. In the northern hemisphere, the net water transport is at 90° to the right of the wind direction, and is known as the Ekman transport.

Ekman spiral Theoretical model to explain the currents that would result from a steady wind blowing over an ocean of unlimited depth and extent. In the northern hemisphere the surface layer of the water would flow at an angle of 45° to the right of the wind direction. Water at increasing depths would flow in directions more to the right, until, at a depth known as the Ekman depth, the water would move in a direction opposite to that of the wind. The Ekman depth varies with latitude but is of the order of 100 m in mid-latitudes. The velocity of the water flow decreases with depth throughout the spiral. In the northern hemisphere, the net water transport is at 90° to the right of the wind direction, and is known as the Ekman transport.