Robot submarine in quest to find why Antarctic glacier is thinning

March 18th, 2009 - 2:27 pm ICT by ANI  

Washington, March 18 (ANI): Scientists are taking the help of a robot submarine to travel under an Antarctic glacier and learn why it has been thinning and accelerating over recent decades.

Autosub, the robot submarine built and developed by the UKs National Oceanography Centre, Southampton, has been exploring Pine Island Glacier, a floating extension of the West Antarctic ice sheet, using sonar scanners to map the seabed and the underside of the ice as it juts into the sea.

Changes in its flow have been observed since the early 1970s, and together with neighboring glaciers, it is currently contributing about 0.25 mm a year to global sea level rise.

Autosub has already successfully completed a high-risk campaign of six missions travelling under the Antarctic glacier.

According to Steve McPhail, who led the Autosub team during the ten-day survey, 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 predefined rendezvous point, where we crane it back onboard the ship, he said.

An international team of scientists led by Dr Adrian Jenkins of British Antarctic Survey and Stan Jacobs of the Lamont-Doherty Earth Observatory, Columbia University, New York on the American ship, the RVIB Nathaniel B Palmer, has been using the robot sub to investigate the underside of the ice and measure changes in salinity and temperature of the surrounding water.

After a test mission in unusually ice-free seas in front of the face of the glacier, they started with three 60 km forays under the floating glacier and extended the length of missions to 110km round-trip.

In all, a distance over 500 km beneath the ice was studied.

Using its sonar, the Autosub picks its way through the water, while creating a three-dimensional map that the scientists will use to determine where and how the warmth of the ocean waters drives melting of the glacier base.

There is still much work to be done on the processing of the data, but the picture we should get of the ocean beneath the glacier will be unprecedented in its extent and detail, said Jenkins.

It should help us answer critical questions about the role played by the ocean in driving the ongoing thinning of the glacier, he added. (ANI)

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