March 17, 2009

Robot Sub Maps Melting Rate Of Antarctic Glaciers

A robot submarine studying the underbelly of an Antarctic ice shelf has found evidence of rising sea levels, scientists reported on Tuesday.

Developed by UK's National Oceanography Center of Southampton, Autosub is an Automated Underwater Vehicle (AUV). It has completed six missions traveling under Pine Island Glacier, an extension of the West Antarctic ice sheet in the Amundsen Sea.

The sub uses sonar to create a three-dimensional map of the seabed and the underside of the ice. Scientists hope to use information gathered by Autosub to reveal why the glacier has been thinning at an increasing rate.

"Autosub is a completely autonomous robot: there are no connecting wires with the ship and no pilot. Autosub has to avoid collisions with the jagged ice overhead and the unknown seabed below, and return to a pre"“defined rendezvous point, where we crane it back onboard the ship," said team leader Steve McPhail.

"Adding to the problems are the sub zero water temperatures and the crushing pressures at 1000 m depth. All systems on the vehicle must work perfectly while under the ice or it would be lost. There is no hope of rescue 60 km in, with 500 meters of ice overhead."

Lead US researcher Stan Jacobs is working with International Polar Year (IPY) funding from the National Science Foundation (NSF) to better understand the dynamics of the world's massive ice sheets.

"Because so little is known about ice sheet behavior, this research will take us a step further in understanding how ice sheets will contribute to sea level rise," said Jacobs, from Columbia University.

If the Pine Island Glacier were to completely melt, it would cause a global sea level rise of about 5 meters, Jacobs said.

"There is still much work to be done on the processing of the data", said Adrian Jenkins, the lead British scientist at the British Antarctic Survey. "But the picture we should get of the ocean beneath the glacier will be unprecedented in its extent and detail. It should help us answer critical questions about the role played by the ocean in driving the ongoing thinning of the glacier."

"My hypothesis is that more water seems to be coming toward the glacier rather than the temperature of the water is rising," he added.


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