NASA satellite yield best ever antartic maps

Rob Gutro/Steve Cole
December 5, 2005
Goddard Space Flight Center, Greenbelt, Md.
(301) 286-4044/3026

RELEASE: 05-55

NASA SATELLITES YIELD BEST-EVER ANTARCTIC MAPS

Scientists using satellite data have now created the most detailed maps ever
produced of the vast snow-covered Antarctic continent. The maps reveal
unprecedented views of surface features that provide clues to how and why
the continent's massive ice sheets and glaciers are changing.

Researchers can now decipher the intricate history of ice movements in the
just-released "Mosaic of Antarctica," which uses images from the Moderate
Resolution Imaging Spectrometer onboard NASA's Terra and Aqua satellites.
The map is the result of a partnership between NASA's Goddard Space Flight
Center, Greenbelt, Md.; the University of Colorado's National Snow and Ice
Data Center (NSIDC), Boulder; and the University of New Hampshire, Durham.

A second map to be released early next year will provide the most complete
and accurate topographical survey of the continent ever undertaken, with
more than 65 million points surveyed from space by the Geoscience Laser
Altimeter System orbiting on NASA's Ice, Cloud and Land Elevation Satellite
(ICESat). This "digital elevation model" produced at Goddard will be
distributed by NSIDC in a format compatible with the Mosaic map.

"The Antarctic Mosaic shows a lot of very subtle changes in the slope of the
terrain that you cannot see from the ground," says Robert Bindschadler,
chief scientist of Goddard's Hydrospheric and Biospheric Sciences
Laboratory. "These subtle variations are important because they tell us the
direction the ice is flowing now and they indicate where it has gone in the
past. The surface roughness also tells us about the bed underneath the ice
and whether the ice is sliding over the bed or frozen to it."

The map will very likely reveal unseen features and new opportunities for
exploration, Bindschadler said. "Antarctica is a big place, and there is
still an awful lot of the ice sheet that hasn't been explored." The new map
will be used by researchers to identify interesting areas and plan
expeditions to investigate them.

The Mosaic removes the terrain distortion and produces a more accurate and
natural-looking view of the continent and its very subtle surface features.
"Using the Mosaic map together with the Canadian satellite, RADARSAT, is a
real breakthrough," says Ted Scambos, one of the creators of the Mosaic at
NSIDC. "The Mosaic shows the snow and rock surface almost perfectly, and
RADARSAT reveals some of the features below the snow. It's very
informative."

The ICESat topographic map complements the Mosaic's detailed views of the
surface with elevation measurements over more of the continent than has ever
been surveyed before. Although the very center of Antarctica remains
unmapped because the satellite does not fly directly over the pole, more of
the interior of the continent was mapped and in unprecedented detail.

"This is the most accurate elevation map of the ice sheet ever produced,
says Jay Zwally, ICESat project scientist at Goddard. "And it will get even
better as ICESat continues to acquire more elevation data for studying
changes in the ice-sheet volume."

The precision of the ICESat map is more than 10 times better than previous
satellite surveys due to the very narrow beam of the laser altimeter
instrument compared to the broader beam of radar instruments flown before.
The improved mapping of the height of the ice sheet, particularly in the
interior of the continent, yields new information about how the topography
of this remote area drives the flow of interior ice streams. Key areas such
as the major ice streams feeding the Ross Ice Shelf are seen in detail for
the first time.

Both maps will be distributed by NSIDC, which serves as one of eight
Distributed Active Archive Centers funded by NASA to archive and distribute
data from NASA's past and current satellites and field measurement programs.
The Mosaic map is available through a user-friendly zoom-in Web interface
that brings together previous maps, such as those from RADARSAT, with new
data in different contrast settings that draw out hard-to-see features. The
NASA-funded interface was developed at the University of New Hampshire by
Mark Fahnestock and Norman Vine.

For images related to this story on the Web, visit:


http://www.nasa.gov/centers/goddard/...ctic_maps.html


For NSIDC's Web site on the Mosaic of Antarctica, visit:


http://www.nsidc.org/data/moa/index.html


For more information about NASA and agency programs on the Web, visit:


http://www.nasa.gov




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Jacques :-)

www.spacepatches.info