NASA Continues Critical Survey Of Antarctica's Changing Ice

WASHINGTON -- Scientists with NASA's Operation IceBridge airborne
research campaign began the mission's third year of surveys this week
over the changing ice of Antarctica.

Researchers are flying a suite of scientific instruments on two planes
from a base of operations in Punta Arenas, Chile: a DC-8 operated by
NASA and a Gulfstream V (G-V) operated by the National Science
Foundation and the National Center for Atmospheric Research. The G-V
will fly through early November. The DC-8, which completed its first
science flight Oct. 12, will fly through mid-November.

Ninety-eight percent of Antarctica is covered in ice. Scientists are
concerned about how quickly key features are thinning, such as Pine
Island Glacier, which rests on bedrock below sea level. Better
understanding this type of change is crucial to projecting impacts
like sea-level rise.

"With a third year of data-gathering underway, we are starting to
build our own record of change," said Michael Studinger, IceBridge
project scientist at NASA's Goddard Space Flight Center in Greenbelt,
Md. "With IceBridge, our aim is to understand what the world's major
ice sheets could contribute to sea-level rise. To understand that you
have to record how ice sheets and glaciers are changing over time."

IceBridge science flights put a variety of remote-sensing instruments
above Antarctica's land and sea ice, and in some regions, above the
ocean floor. The G-V carries one instrument: a laser-ranging
topography mapper. The DC-8 carries seven instruments, including a
laser altimeter to continue the crucial ice sheet elevation record
begun by the Ice, Cloud and land Elevation Satellite (ICESat)
mission, which ended in 2009. The flying laboratory also will carry
radars that can distinguish how much snow sits on top of sea ice and
map the terrain of bedrock below thick ice cover.

While scientists in recent years have produced newer, more detailed
data about the ice sheet's surface, the topography of the rocky
surface beneath the ice sheet remains unknown in many places. Without
knowing the topography of the bedrock, it is impossible to know
exactly how much ice sits on top of Antarctica.

A gravimeter aboard the DC-8 will detect subtle differences in gravity
to map the ocean floor beneath floating ice shelves. Data on
bathymetry, or ocean depth, and ocean circulation from previous
IceBridge campaigns are helping explain why some glaciers are
changing so quickly.

Flights take off from Punta Arenas and cross the Southern Ocean to
reach destinations including West Antarctica, the Antarctic Peninsula
and coastal areas. Each lasts 10 to 11 hours.

"We will be re-surveying our previous flight lines to see how much
glaciers and ice sheets have changed, and we'll cover new areas to
establish a baseline for future years and the ICESat-2 mission in
2016," Studinger said.

Early high-priority DC-8 flights include several flight lines over sea
ice near the Antarctic Peninsula, before too much of the ice melts in
the southern spring. IceBridge sea ice flights are designed to help
scientists understand why sea ice in the Southern Hemisphere is not
following the steady decline of sea ice thickness and extent seen in
the Arctic.

Other high priority flight lines follow ground traverses being made
this year and next, during which NASA scientists will travel
different sections of the West Antarctic Ice Sheet, measuring
snowfall accumulation and the characteristics of Pine Island Glacier.

Many flight lines will retrace either previous ICESat-1 tracks or
future ICESat-2 tracks. Some also will align with current
observations made by the European Space Agency's CryoSat-2 satellite.
The overlapping flight lines and satellite tracks ultimately will
help scientists improve the accuracy of their data.

NASA's Ames Research Center in Moffett Field, Calif., is responsible
for IceBridge project management. The DC-8 is based at NASA's Dryden
Aircraft Operations Facility in Palmdale, Calif.

To follow the mission in more detail, visit:

http://www.nasa.gov/icebridge

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