Ekman Transport and Coastal Upwelling
May 03, 2001
Today marks the birth date in 1874 of V. Walfrid Ekman, a Swedish physical oceanographer best known for his studies of the dynamics of ocean currents. Norwegian Arctic explorer Fridjof Nansen observed that arctic sea ice moved 20-40º to the right of wind direction. He passed his observations to Ekman who showed that due to the Coriolis effect surface water moves in a direction 45º relative to wind direction. This movement of surface water is responsible for upwelling of cold nutrient rich water along some coastal areas, as seen in this SeaWiFS image of the Agulhas and Bengeula currents off of the southern tip of Africa. Winds paralleling the shoreline drive the surface water oceanward, causing the upwelling of nutrient rich water, seen here in false color as orange and yellow representing high concentrations of phytoplankton.