WASHINGTON -- Scientists and flight crew members with Operation
IceBridge, NASA's airborne mission to study Earth's changing polar ice,
are beginning another campaign over Antarctica. Now in its fourth year,
IceBridge's return to the Antarctic comes almost a year after the
discovery of a large rift in the continent's Pine Island Glacier.
The first science flight of the campaign began Friday at 8 a.m. EDT
when NASA's DC-8 research aircraft left Punta Arenas, Chile, for an
11-hour flight that will take it over the Thwaites Glacier in west
Antarctica. This year, IceBridge will survey previously unmeasured areas
of land and sea ice and gather further data on rapidly changing areas
like Pine Island Glacier. The IceBridge Antarctic campaign will operate
out of Punta Arenas through mid-November.
Several of
IceBridge's planned flights focus on previously unmeasured ice streams
feeding into the Weddell Sea. These flights will gather data on what
lies beneath these ice streams, something vital for understanding how
changing conditions might affect the flow of ice into the ocean and
sea-level rise.
"We have added surveys of ice streams flowing
into the Ronne and Filchner ice shelves," said IceBridge project
scientist Michael Studinger at NASA's Goddard Spaceflight Center in
Greenbelt, Md. "This is something we haven't done before."
The large crack in Pine Island Glacier's floating ice shelf has been the
focus of worldwide attention as it has grown. The ice shelf now
threatens to calve, or break off, a large iceberg into Pine Island Bay
in the Amundsen Sea. Researchers have been using imagery from NASA's
Aqua and Terra spacecraft and synthetic aperture radar data from the
German Aerospace Center's TerraSAR-X satellite to monitor the rift since
its discovery last year.
IceBridge also will gather data on
sea ice in the Weddell and Bellingshausen seas. Because of geographical
differences, Antarctic sea ice behaves differently from ice in the
Arctic and presents unique challenges.
"Sea ice in the Antarctic is a very different physical system," Goddard sea ice researcher Nathan Kurtz said.
Ocean currents, precipitation patterns and the shape of land masses
are just a few of the differences. Instead of compacting ice against
land like in the Arctic basin, currents in the Southern Ocean push much
of it farther out to sea. Also, the Antarctic averages more snowfall,
which weighs sea ice down and allows ocean water into the bottom layer
of the snow on top of the sea ice. The Antarctic has more frequent
strong wind events and large temperature swings than the Arctic, which
causes layers of ice to form in snow cover. Both of these factors make
getting accurate readings of snow on top of sea ice challenging.
Arctic sea ice extent and volume reached record lows this year, but
Antarctic sea ice volume has been holding steady and the extent has been
increasing. Predictive models have a hard time pinpointing what
Antarctic sea ice might do under a warming global climate. Having more
data to work with could make these models more useful. Further
observations will give researchers more data on how Antarctic sea ice
changes over time.
"This is why having observations is really
important," Kurtz said. "We want to make sure these models are getting
the physics right.
IceBridge will gather information on many
different aspects of land and sea ice using a variety of scientific
sensors onboard the DC-8. These instruments include a laser altimeter to
measure surface elevation changes, various radar instruments for
determining snow depth and ice thickness, a gravimeter that will gather
data on the size and shape of water cavities under ice shelves, and a
digital camera instrument that takes high-resolution images useful for
building maps and digital elevation models of the ice.
By
flying previously surveyed tracks in rapidly changing areas like Pine
Island Glacier, IceBridge is building on a legacy of measurements
started by NASA's ICESat satellite that will continue with the launch of
ICESat-2 in 2016.
"This area is changing so rapidly we need to survey every year," Studinger said.
In addition, IceBridge will fly along tracks for the European Space Agency's ice-monitoring satellite, CryoSat-2.
This year's campaign also will see visits to IceBridge by school
teachers. Two English-speaking Chilean science teachers will meet with
IceBridge scientists and instrument operators this month and ride on a
survey flight to learn more about polar science research with the goal
of using their new knowledge to better engage and teach students.
The IceBridge project science office is based at Goddard. The DC-8 is
based at NASA's Dryden Aircraft Operations Facility in Palmdale, Calif.
For more information, images and video of Operation IceBridge, visit:
http://www.nasa.gov/icebridge
For more information about ICEsat-2, visit:
Arctic Sea Ice Hits Smallest Extent In Satellite Era
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Satellite data reveal how the new record low Arctic sea ice extent, from
Sept. 16, 2012, compares to the average
minimum extent over the past 30 years (in yellow). Sea ice extent maps
are derived from data captured by the Scanning Multichannel Microwave
Radiometer aboard NASA's Nimbus-7 satellite and the Special Sensor
Microwave Imager on multiple satellites from the Defense Meteorological
Satellite Program. Credit: NASA/Goddard Scientific
Visualization Studio
The frozen cap of the Arctic Ocean appears to have reached its annual
summertime minimum extent and broken a new record low on Sept. 16, the
National Snow and Ice Data Center (NSIDC) has reported. Analysis of
satellite data by NASA and the NASA-supported NSIDC at the University of
Colorado in Boulder showed that the sea ice extent shrunk to 1.32
million square miles (3.41 million square kilometers).
The new record minimum measures almost 300,000 square miles less than
the previous lowest extent in the satellite record, set in mid-September
2007, of 1.61 million square miles (4.17 million square kilometers).
For
comparison, the state of Texas measures around 268,600 square miles.
NSIDC cautioned that, although Sept. 16 seems to be the annual minimum,
there's still time for winds to change and compact the ice floes,
potentially reducing the sea ice extent further. NASA and NSIDC will
release a complete analysis of the 2012 melt season next month, once all
data for September are available.
Arctic sea ice cover naturally grows during the dark Arctic winters and
retreats when the sun re-appears in the spring. But the sea ice minimum
summertime extent, which is normally reached in September, has been
decreasing over the last three decades as Arctic ocean and air
temperatures have increased. This year's minimum extent is approximately
half the size of the average extent from 1979 to 2000. This year's
minimum extent also marks the first time Arctic sea ice has dipped below
4 million square kilometers.
"Climate models have predicted a retreat of the Arctic sea ice; but the
actual retreat has proven to be much more rapid than the predictions,"
said Claire Parkinson, a climate scientist at NASA Goddard Space Flight
Center, Greenbelt, Md. "There continues to be considerable inter-annual
variability in the sea ice cover, but the long-term retreat is quite
apparent."
The thickness of the ice cover is also in decline.
"The core of the ice cap is the perennial ice, which normally survived
the summer because it was so thick", said Joey Comiso, senior scientist
with NASA Goddard. "But because it's been thinning year after year, it
has now become vulnerable to melt".
The disappearing older ice gets replaced in winter with thinner seasonal ice that usually melts completely in the summer.
Related Links:
› NSIDC's Arctic Sea Ice News & Analysis
› NASA Sea
Ice Imagery
NASA
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
