December 5, 2011

Scientists Map Out What’s Below Antarctica’s Ice

Scientists have created a detailed map called BEDMAP of Antarctica's rock bed that lies underneath its icy surface.

The map gives a view of the landscape beneath the ice, and incorporates decades of survey data acquired by planes, satellites, ships and even people on dogsleds.

In the map, the highest elevations are marked in red/black, while the light blue color shows the extent of the continental shelf.  The lowest elevations are dark blue, some of which lie below today's seal level.

The type of information displayed through the BEDMAP will help researchers understand the pace of future events like ice melting.

"This is information that underpins the models we now use to work out how the ice flows across the continent," Hamish Pritchard from the British Antarctic Survey (BAS) told BBC. "The Antarctic ice sheet is constantly supplied by falling snow, and the ice flows down to the coast where great bergs calve into the ocean or it melts. It's a big, slow-speed hydrological cycle.

"To model that process requires knowledge of some complex ice physics but also of the bed topography over which the ice is flowing - and that's BEDMAP."

This is the second version of the digital BEDMAP.  The first was produced in 2001 and incorporated 1.9 million measurements points.

BEDMAP 2 now enlists more than 27 million points on a grid spacing about 3 miles.  This increase in points is largely due to the number of airborne radar surveys that have been flown over the continent.

Planes guided by GPS carry instruments that are able to fire microwave pulses through the overlying ice sheet, recording the return echoes.  Scientists are able to plot both the depth of the rock bed and the thickness of the ice covering it by using these echoes.

A multinational expedition in 2007 and 2008 revealed the Gamburtsev mountains, which reach the size of the European Alps at almost 10,000 feet.  They also found that about 3,200 feet of ice cover these mountains.

Despite the 27 million points of measurements taken, there is still areas of Antarctica's bed rock that have not been pinned down yet.  Scientists hope to gain more funding from national agencies to go and have a better look at some of these areas.


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