Wednesday, November 18, 2009

Lake Superior research news

From UW Madison:


MADISON - Rising water temperatures are kicking up more powerful winds on Lake Superior, with consequences for currents, biological cycles, pollution and more on the world's largest lake and its smaller brethren.

Since 1985, surface water temperatures measured by lake buoys have climbed 1.2 degrees per decade, about 15 percent faster than the air above the lake and twice as fast as warming over nearby land.

"The lake's thermal budget is very sensitive to the amount of ice cover over the winter," says Ankur Desai, atmospheric and oceanic sciences professor at the University of Wisconsin-Madison. "There is less ice on Lake Superior during the winter, and consequently the water absorbs more heat."

A wide temperature differential between water and air makes for a more stable atmosphere with calmer winds over the relatively cold water. However, as warming water closes the gap, as in Lake Superior's case, the atmosphere gets more turbulent.

"You get more powerful winds," Desai says. "We've seen a 5 percent increase per decade in average wind speed since 1985."

Those findings will be published Nov. 15 in the journal Nature Geoscience.

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