Monday, March 20, 2006

Scientists use satellites to detect deep-ocean whirlpools

DELAWARE (20 Mar 2006) -- Move over, Superman, with your X-ray vision. Marine scientists have now figured out a way to "see through" the ocean's surface and detect what's below, with the help of satellites in space.

Using sensor data from several U.S. and European satellites, researchers from the University of Delaware, NASA's Jet Propulsion Laboratory, and the Ocean University of China have developed a method to detect super-salty, submerged eddies called "Meddies" that occur in the Atlantic Ocean off Spain and Portugal at depths of more than a half mile. These warm, deep-water whirlpools, part of the ocean's complex circulatory system, help drive the ocean currents that moderate Earth's climate.

The research marks the first time scientists have been able to detect phenomena so deep in the ocean from space -- and using a new multi-sensor technique that can track changes in ocean salinity.

The lead author of the study was Xiao-Hai Yan, Mary A. S. Lighthipe Professor of Marine Studies at the University of Delaware and co-director of the UD Center for Remote Sensing. His collaborators included Young-Heon Jo, a postdoctoral researcher in the UD College of Marine Studies, W. Timothy Liu from NASA's Jet Propulsion Laboratory in Pasadena, California, and Ming-Xia He, from the Ocean Remote Sensing Institute at the Ocean University of China in Qingdao, China. Their results are reported in the April issue of the American Meteorological Society's Journal of Physical Oceanography.

"Since Meddies play a significant role in carrying salty water from the Mediterranean Sea into the Atlantic, new knowledge about their trajectories, transport, and life histories is important to the understanding of their mixing and interaction with North Atlantic water," Yan notes. "Ultimately, we hope this information will lead to a better understanding of their impact on global ocean circulation and global climate change."

First identified in 1978, Meddies are so named because they are eddies -- rotating pools of water -- that flow out of the Mediterranean Sea. A typical Meddy averages about 2,000 feet (600 meters) deep and 60 miles (100 kilometers) in diameter, and contains more than a billion tons (1,000 billion kilograms) of salt.

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