Oceans Blue: Giant Swirl Captured
An instrument aboard NASA's Terra satellite captured this natural-color image of a deep-ocean eddy containing a phytoplankton bloom off the coast of South Africa. The enormous eddy, imaged on Dec. 26, 2011, likely peeled off from the Agulhas Current.
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The ocean has storms and weather that rival the size and scale of tropical cyclones. But rather than destruction, these storms—better known as eddies—are more likely to bring life to the sea...and often in places that are otherwise barren.

Shown here, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured a natural-color image of such a deep-ocean eddy on Dec. 26, 2011. The 93-mile (150 kilometer)-wide swirl contains a bloom of phytoplankton (traced in light blue) and resides about 500 miles (800 km) south of South Africa. The counter-clockwise eddy likely peeled off from the Agulhas Current, which flows along the southeastern coast of Africa and around the tip of South Africa. Agulhas eddies, also called “current rings,” tend to be among the largest in the world, transporting warm, salty water from the Indian Ocean to the South Atlantic.

Some eddies, like this one, stir up the ocean enough to draw nutrients up from the deep, fertilizing the surface waters and sparking blooms of tiny plantlike organisms.
Credit: NASA Earth Observatory image created by Jesse Allen
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