NSF PR 98-68 - October 14, 1998
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SHEBA Breaks Free of Arctic's Icy Embrace
The Canadian Coast Guard icebreaker Des Groseilliers
has left the ice floe it has called home for more
than a year and is expected in Prudhoe Bay, Alaska,
later this week, concluding the field season of the
largest and most complex project ever supported in
the Arctic by the National Science Foundation (NSF).
"We've observed the ice, the atmosphere and the ocean
over a full annual cycle covering the physical variables
in all three systems. We've seen it all: melting,
freezing, heating, cooling, ridges, cracks, leads,
melt ponds and all kinds of different formations of
ice and snow," said Richard Moritz, polar scientist
with the University of Washington's Applied Physics
Laboratory and director of the SHEBA project office
based at the university. The Des Groseilliers is expected
to anchor off Prudhoe Bay Oct. 14 or 15 to offload
personnel and cargo.
Purposely frozen into the ice pack early last October,
the Des Groseilliers became the heart of Ice Station
SHEBA, short for the Surface Heat Budget of the Arctic
Ocean. It is a $19.5 million research effort to gather
data to improve Arctic climate models and, in turn,
global forecasts of climate change, said Mike Ledbetter,
director for NSF's Arctic System Science Program.
The Arctic ice pack undergoes profound changes every
year. In winter, the ice pack is about the size of
the continental United States; in summer, there is
only half as much ice. Understanding what controls
this annual freeze and meltdown is a key to predicting
future climate change and assessing the toll of global
warming, whether it's natural or human-caused.
Warming could, for instance, affect westerly winds
and change weather patterns in the northern hemisphere,
Ledbetter says. It certainly would affect the web
of life in the Arctic that ranges from microscopic
algae on the sea ice to 1,600-pound polar bears that
roam the surface.
A better understanding of the consequences of global
warming in the Arctic would be important as world
governments debate options that range from doing nothing
to taking drastic steps to curtail the production
of greenhouse gases.
SHEBA documented how such things as clouds, snow, ice
and the ocean interact and exchange energy over the
course of a year. "The data collected is unprecedented
and will be used for decades to improve climate predictions,"
Ledbetter said.
The ice station, funded by NSF with support from the
Office of Naval Research and the Japanese government,
was located on a floe that originally was 5 miles
by 6 miles. The station consisted of a collection
of plywood research huts, cold-weather tents, meteorological
towers, automatic buoys and stands of instruments
surrounding the Des Groseilliers. The icebreaker was
used under an agreement between the Office of Naval
Research, NSF and Canadian Department of Fisheries
and Oceans.
Small planes able to land on the ice and U.S. icebreakers
provided the means to rotate scientists and crew during
the experiment. The number of scientists working on
site ranged from 15 in mid-winter to about 35 last
spring.
Data also was gathered by sensors on six spacecraft,
by researchers using four different kinds of aircraft
and by a submarine prowling beneath the ice cap. The
work was done in collaboration with U.S. agencies
such as Department of Energy, NASA and the Navy. SHEBA
was concerned with how the climate of the Arctic works,
not with trying to determine if global warming is
underway in the Arctic Ocean, Moritz said. Nevertheless,
scientists were surprised in October 1997 that the
water was much fresher than in measurements made in
the same area 20 years ago. It was determined that
the melting of the ice pack during the summer of 1997
caused the lower salinity. The findings were published
in Geophysical Research Letters in May.
The ice where the station was established a year ago
also was thinner than expected, Moritz says. Scientists
had hoped to find ice of two to three meters in that
area but despite searching some 50 miles farther north,
settled on a floe that was between 1.6 and 1.8 meters
thick. Going even farther north would have placed
SHEBA beyond the limit of the Twin Otter aircraft
used most of the year to reach the ice station from
mainland Alaska.
Factors at work since last fall, including some effects
from the El Nino event, produced a winter where the
pack didn't thicken as much as seasoned ice experts
had expected. Preliminary analyses of late summer
measurements indicate that the floe lost more ice
than it gained last winter.
Weather, ice and ocean conditions also combined in
unexpected ways to move the floe farther and faster
from its starting point than anyone predicted. Originally
frozen in about 300 miles north of Prudhoe Bay, the
floe was shoved along a meandering, 1,000-mile path
ending up about 400 miles northwest of where it started.
Along with moving the ice floe, sometimes at a rate
of 20 miles a day, the wind and ocean currents rearranged
the station itself a number of times. During blizzard
conditions in early April, for instance, the part
of the camp with a 70-foot meteorological tower and
seven huts migrated a quarter-mile away from the ship
- overnight.
For more information, see: http://sheba.apl.washington.edu
Editors: B-roll is available on Betacam
SP. New images of the ship's departure are expected
by early November. Contact Dena Headlee at 1-888-937-5249
(pager).
Attachment: FACT SHEET:
SHEBA Quick Facts and Figures
Attachment
FACT SHEET: SHEBA Quick Facts and Figures
Background: Ice Station SHEBA (Surface Heat Budget of the Arctic Ocean)
is completing one year of being frozen in the Arctic
ice gathering information to improve climate modeling.
- Ship (Des Groseilliers) froze into the Arctic ice
pack Oct. 2, 1997 and pulled away Oct. 11, 1998.
- Ice Station SHEBA originally froze in at 75 degrees
North and 143 degrees West, about 300 miles north
of Deadhorse, Alaska. When the station concluded,
it was at 80 degrees north and 166 degrees west, about
400 miles northwest of where it started.
- Des Groseilliers: 322 feet long; French-Canadian
crew. After leaving Prudhoe Bay, expected to arrive
in Quebec City Oct. 28.
- The last ship to sit deliberately in the ice pack
for more than a year was the Fram, a Norwegian vessel
that was frozen into the ice in 1893 for the purpose
of scientific exploration. The Fram drifted for nearly
three years before being able to break free.
- The smallest science party was 15 in the dead of
winter and between 35 and 40 during spring's most
intense periods. The Canadian Coast Guard crew consisted
of 16 members, about half the number when the ship
is underway.
- More than 170 scientists worked at the station at
one time or another including principal investigators,
technicians and graduate students. Most rotated at
regular intervals, however, one American stayed six
months straight and one Canadian biologist never left
the station.
- More than 50 U.S. researchers received SHEBA funding
from the National Science Foundation and Office of
Naval Research to conduct projects. Other agencies
funding research at the station included the U.S.
Department of Energy, NASA, the Canadian Department
of Fisheries and Oceans and the Japanese government.
- The coldest temperature recorded at the station
was about - 42 C on New Year's Eve. The warmest was
0.8 C on July 20, 1998.
- Throughout the year, there were occasional visits
by polar bears. The largest number of bear sightings
occurred in the interval between mid-May and late
June. It is estimated that at least 10 different bears
were sighted in the vicinity of the station. A family
comprising a mother with two cubs stayed in the general
area of the station for 1 1/2 weeks.
- One example of the problems with current climate
models of the Arctic: Current models of the Arctic
climate can give vastly different results when considering
various scenarios. For instance, some models say doubling
the amount of carbon dioxide in the earth's atmosphere
(something scientists feel is likely to happen within
the next 50 to 100 years) will make the Arctic ice
pack half as large as it is today. Others predict
it will disappear completely.
- Instruments used at Ice Station SHEBA ranged from
simple meter sticks stuck in the snow to a state-of-the-art
cloud LIDAR that monitored clouds by scanning a laser
across the sky. Sensors were hung from tethered balloons
and were mounted on three different metal towers,
the ship deck and on the ice.
- Mother Nature rearranged parts of the station on
numerous occasions during the winter. For example,
it took a mere 15 minutes for two pieces of ice to
come together at the bow of the ship with enough force
to push up a 10-foot tall ridge of ice. Teetering
half on and half off the ridge was a cold-weather
tent housing three snowmobiles. Everyone, from crew
to scientists to cooks, went to work with ropes and
pulleys to lower the snowmobiles down from the ridge
that continued moving and buckling while everyone
concentrated on the task at hand.
- Summer brought a slowly rising flood of melt ponds,
open water and soft surfaces. The team that was used
to riding snowmobiles to their work areas half a mile
from the ship, went from riding to walking the distance,
to having to build snow bridges over soft parts so
they could walk, to using a row boat to traveling
by helicopter - all in a matter of weeks. That same
group once got a call on the radio from a group at
work on a different part of the floe saying they'd
just seen one of their stations float by.
For more information, see: http://sheba.apl.washington.edu
Photo highlights of the year are at: http://sheba.apl.washington.edu/shipimages/images.html
(Note: Media outlets can obtain high-resolution images
from SHEBA by calling Sandra Hines, University of
Washington)
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