The rising of water along the equator from about 200 m to the surface. It occurs in the Atlantic and Pacific Oceans where the Southern Hemisphere trade winds reach into the Northern Hemisphere, giving uniform wind direction on either side of the equator. Because the surface currents of the Ekman spiral are deflected to different sides of the wind in both hemispheres, the surface water is drawn away from the equator, causing the colder water from deeper layers to upwell.