Ekman transport
Also called: Ekman spiral · Topic: Movements of Ocean Water: Waves, Tides and Currents · NCERT: Beyond NCERT
Meaning
Ekman transport is the movement of wind-driven surface water at right angles to the wind. It turns to the right in the Northern Hemisphere and to the left in the Southern. The scientist V.W. Ekman explained it in 1905. Wind drags the top layer of water, and the Coriolis force (the turning effect of Earth's rotation) bends it. Each deeper layer is dragged by the one above and turns a little more. Taken together, the wind-driven layer moves sideways to the wind. This pushes surface water away from some coasts, and cold water rises from below to replace it. That rising is called upwelling.
Example
Off the coast of California, winds blow south along the shore. Ekman transport pushes surface water out to sea, and cold, nutrient-rich water wells up. This brings fog and rich fishing.
Don't confuse with
- Ekman spiral: the twisting pattern of the separate layers, each one turned a little more than the one above. Ekman transport is the overall sideways movement of the whole layer.
Related concepts
- Ocean current
- Forces driving ocean currents
- Gyre
- Surface currents
- Deep water currents
- Warm current
- Cold current