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Deep-sea currents driven by wind.

Two researchers recently confirmed what oceanographers have suspected for 40 years--that long-term cycles of wind can drive deep ocean currents. The surprise, though, was not in the confirmation of the old theory but in the reassuring finding that present methods for mapping the wind are accurate enough for scientists to construct meaningful dynamic models of wind and ocean currents, Chester Koblinsky of NASA Goddard Space Flight Center in Greenbelt, Md., told SCIENCE NEWS.

Koblinsky and Pearn Niiler of Scripps Institution of Oceanography in La Jolla, Calif., compared ocean currents, measured with a moored current meter, with 10- to 100-day wind cycles in the North Pacific derived from previously collected data. They found that ocean currents 150 to 4,000 meters below the surface are directly related to surface wind shear forces, they report in the Aug. 23 SCIENCE.

This phenomenon probably applies to the midlatitudes of the eastern ocean basins, wherever winds are very intense, says Koblinsky. But powerful western boundary currents, such as the Gulf Stream and the Pacific's Kurishio, would tend to overwhelm the effects of the wind, he says.

Maps of global wind patterns are presently constructed from the four-times-daily reports of merchant vessels all over the world and from satellite photos of clouds. Because ships mostly confine themselves to a few major routes in the northern hemisphere and avoid storms, these data have long been considered of dubious value, says Koblinsky. "It's really comforting to the oceanographic community to know that the measurements are good enough," he says.

Good enough, that is, to model the ocean for studies of the earth's climate and weather, he says. "The ocean is the missing link for climate," says Koblinsky.

On another front, NASA is planning to begin measuring global wind patterns from space in about five years, according to Koblinsky.

Because of the newly demonstrated usefulness of present wind measurements, he and his colleagues are impatient to get the much more accurate and complete global wind measurements from space for their models.
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Publication:Science News
Date:Aug 31, 1985
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