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Men working on an instrument in the snow.
Photo Credit: NASA PIG Web site
A trio of scientists adjusts hoses and couplings on the hotwater drill during a "dress rehearsal" of the profiler system last year at Windless Bight near McMurdo Station. The researchers will begin the first of two field seasons on the ice shelf in 2011-12.

 

Ridge is a game-changer

“The ridge has changed the show,” said Tim Stanton External Non-U.S. government site, a scientist in the Oceanography Department at the Naval Postgraduate School External Non-U.S. government site. His lab designs, builds and deploys unique ocean profilers, a system of instruments that moves vertically up and down on a cable through the entire water column, with power and communications at the surface. Its job is to measure and monitor the complex ocean currents swirling below the ice.

The ridge is a game-changer because it means that any deployment of the ocean profiler upstream of the ridge — remember that the ice flows toward the ocean — might have hit the raised seafloor. Now any upstream deployment of the instrument package will have to account for the ridge.

The ridge was discovered in 2009 during a research cruise aboard the USAP’s Nathaniel B. Palmer External U.S. government site, led by chief scientist Stan Jacobs External Non-U.S. government site, an oceanographer at Lamont-Doherty Earth Observatory at Columbia University External Non-U.S. government site. [See previous article: Pine Island cruise.]

A British team aboard the ship sent a robotic submarine underneath the ice shelf where it mapped various properties of the underwater cavity, discovering the ridge along the way. [See previous article: Rapid retreat.]

Torpedo-shaped instrument on a ship.
Photo Credit: British Antarctic Survey
BAS autosub prepares for deployment under PIG ice shelf.
Tower of instruments sits on ice sheet.
Photo Credit: NASA PIG Web site
Communications tower for the ocean profiler.
Small animal down a hole.
Photo Credit: NASA
Shrimplike critter found in ice borehole.

“It was really a blessing to have that information. Otherwise, it was a blank slate,” Bindschadler said of the data retrieved by the yellow submarine. “The annoying thing about the ridge is that our instruments can’t touch the floor.”

The British are also collaborators on the PIG project. A British Antarctic Survey (BAS) External Non-U.S. government site plane will fly over the region from BAS’ base at Rothera Station External Non-U.S. government site off the Antarctic Peninsula this year. The plane’s radar will provide additional details about the ice shelf that will be useful for planning the 2011-12 and 2012-13 field campaigns.

“[Pine Island] has been a focus for us for quite a few years,” said David Vaughan External Non-U.S. government site, a scientist at BAS who attended the strategy session at Penn State. “Pine Island is the biggest red dot” for climate change in Antarctica, he added.

Two American teams will also head to the Ice this season on separate missions.

David Holland External Non-U.S. government site will lead a two-person team to the edges of the glacier to recover an existing automatic weather station (AWS) he installed three years ago and move it to the PIG camp being set up this season.

Director of the Center for Atmosphere Ocean Science at New York University External Non-U.S. government site, Holland will also attempt to install three additional AWS systems in the region.

Meanwhile, Stanton and a separate team will join New Zealand researchers at a field camp near Erebus Ice Tongue, a glacier that pokes out about 10 kilometers into McMurdo Sound from the Ross Island coastline near Cape Evans.

The U.S. scientists will conduct a second test of the ocean profiler system on the sea ice. Last year’s “dress rehearsal” of the project successfully punched through the 200-meter-thick section of ice shelf near McMurdo Station with a hotwater drill. [See previous article: Dress rehearsal.]

It was the first time scientists had deployed such a complex ocean profiler beneath an Antarctic ice shelf, even discovering a wee marine organism with a borehole camera that preceded the profiler down the fresh hole.

However, the system malfunctioned shortly after the team left. Stanton believes he has worked out the problem and wants another shot at testing the equipment before the team does it for real in about a year.

By then there will be little room for mistakes among the crevasse fields of the Pine Island Glacier Ice Shelf.

“We’re going to be eager to bang this camp in,” Stanton said.

NSF-funded research in this story: Robert Bindschadler and Alberto Behar, Goddard Space Flight Center, Award No. 0732906 External U.S. government site; Tim Stanton, Naval Postgraduate School, Award No. 0732926 External U.S. government site; David Holland, New York University, Award No. 0732869 External U.S. government site; Sridhar Anandakrishnan, Penn State University, Award No. 0732844 External U.S. government site; Miles McPhee, McPhee Research Company, Award No. 0732804 External U.S. government site; and Martin Truffer, University of Alaska, Fairbanks, Award No. 0732730 External U.S. government site.

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Curator: Peter Rejcek, Antarctic Support Contract | NSF Official: Winifred Reuning, Division of Polar Programs