Sea Ice Changes David E. Steitz

Headquarters, Washington DC

(Phone: 202/358-1730)

Susan Mitgang

Jet Propulsion Laboratory, Pasadena, CA

(Phone: 818/354-5011)

RELEASE: 00-128

NASA researchers have new insights into the mysteries of Arctic sea ice,
thanks to the unique abilities of Canada’s RADARSAT satellite. The Arctic is the
smallest of the world’s four oceans, but it may play a large role in helping
scientists monitor Earth’s climate shifts.

Using RADARSAT’s special sensors to take images at night and to peer
clouds, NASA researchers can now see the complete ice cover of the Arctic. This
allows tracking of any shifts and changes, in unprecedented detail, over the
course of an entire winter. The radar-generated, high-resolution images are up
100 times better than those taken by previous satellites.

Using this new information, scientists at NASA’s Jet Propulsion Laboratory
(JPL), Pasadena, CA, can generate comprehensive maps of Arctic sea ice thickness
for the first time. “Before we knew only the extent of the ice cover,” said Dr.
Ronald Kwok, JPL principal investigator of a project called Sea Ice Thickness
Derived From High Resolution Radar Imagery. “We also knew that the sea ice
had decreased over the last 20 years, but we knew very little about ice

“Since sea ice is very thin, about 10 feet (3 meters) or less,” Kwok
explained, “it is very sensitive to climate change.”

Until now, observations of polar sea ice thickness have been available for
specific areas, but not for the entire polar region.

The new radar mapping technique has also given scientists a close look at
how the sea ice cover grows and contorts over time. “Using this new data set, we
have the first
estimates of how much ice has been produced and where it formed during the
winter. We have never been able to do this before,” said Kwok. “Through our
maps of the Arctic Ocean, we can actually see ice breaking apart and thin ice
growth in the new openings.”

RADARSAT gives researchers a piece of the overall puzzle every three days
creating a complete image of the Arctic. NASA scientists then put those puzzle
pieces together to create a time-lapsed view of this remote and inhospitable
region. So far, they have processed one season’s worth of images.

“We can see large cracks in the ice cover, where most ice grows,” said
“These cracks are much longer than previously thought, some as long as 1200
(2000 kilometers).” Kwok continued, “If the ice is thinning due to warming,
expect to see more of these long cracks over the Arctic Ocean.”

Scientists believe this is one of the most significant breakthroughs in the
last two decades of ice research. “We are now in a position to better understand
the sea ice cover and the role of the Arctic Ocean in global climate change,”
said Kwok.

Radar can see through clouds and any kind of weather system, day or night,
and as the Arctic regions are usually cloud-covered and subject to long, dark
winters, radar is proving to be extremely useful. However, compiling these data
into extremely detailed pictures of the Arctic is a challenging task.

“This is truly a major innovation in terms of the quantities of data being
processed and the novelty of the methods being used,” said Verne Kaupp, Director
of the Alaska SAR Facility at the University of Alaska, Fairbanks.

The mission is a joint project between JPL, the Alaska SAR Facility, and
Canadian Space Agency. Launched by NASA in 1995, the RADARSAT satellite is
operated by the Canadian Space Agency. JPL manages the Sea Ice Thickness Derived
From High Resolution Radar Imagery project for NASA’s Earth Science Enterprise,
Washington, DC. The Earth Science Enterprise is dedicated to studying how
and human-induced changes affect our global environment.

More information on this mission can be found on the Internet at:

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