Robotic underwater gliders observe melting Antarctic ice sheets

"The use of ocean gliders is beginning to revolutionize our understanding of polar ocean processes," said Karen Heywood.
By Brooks Hays   |   Nov. 11, 2014 at 11:34 AM

PASADENA, Calif., Nov. 11 (UPI) -- Three robotic underwater gliders deployed in the Southern Ocean are helping scientists in the United States and United Kingdom better understand Antarctica's shrinking ice sheets.

It's clear that warmer ocean waters near the coast play a role in melting Antartica's ice, but researchers wanted to get a better read on how that water gets there, and why. The gliders offered scientists a chance to find out, by tracking warm Southern Ocean waters on their elusive journey to the Antarctic coast.

It turns out swirling, storm-like ocean eddies transport warm water from deep ocean currents to the shallow surface waters of coastal Antarctica. Once delivered, these warm waters heat the polar ice sheets from below as the atmosphere melts the glaciers from above.

"Eddies are instabilities that are caused by ocean currents, and we often compare their effect on the ocean to putting a spoon in your coffee," Andrew Thompson, assistant professor of environmental science and engineering at Caltech, explained in a press release.

Thompson is the lead author of a new study on the melting effects of Southern Ocean eddies; the scientific paper was published this week in the journal Nature Geoscience.

"If you pour milk in your coffee and then you stir it with a spoon, the spoon enhances your ability to mix the milk into the coffee and that is what these eddies do," Thompson added. "They are very good at mixing heat and other properties."

Deployed and controlled by researchers at the University of East Anglia in England and the California Institute of Technology, the robotic gliders can explore underwater for long periods of time, rising only periodically to beam back collected data -- temperature, salinity and current movement -- via satellites and cell towers.

Because the eddies are hard to predict and seemingly sporadic, a device like the glider -- which can easily outlast the research capabilities of a vessel and crew manually lower instruments into the water -- was invaluable.

"The use of ocean gliders is beginning to revolutionize our understanding of polar ocean processes," study co-author Karen Heywood, a professor at East Anglia's Center for Ocean and Atmospheric Sciences, told the BBC. "We hope it will help refine ocean and climate models, and predict future rates of retreat for Antarctic ice shelves."

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