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NASA, Europe find ozone loss over Arctic
 While
areas of the United States experienced days of record warm
temperatures this past winter, NASA Langley scientists found record
cold in the Arctic stratosphere. These cold temperatures
contributed to more than 60 percent ozone loss - one of the worst
ever reported at this altitude near the North Pole.
According to reports from NASA's
SAGE III Ozone Loss and Validation Experiment (SOLVE)
and the European Commission-sponsored
Third European Stratospheric Experiment on Ozone (THESEO)
2000, large ozone losses were observed inside the Arctic
stratospheric polar vortex. The polar vortex is a large, swirling
air mass with its thickest layer of ozone near 60,000 feet.
Six teams of NASA Langley
scientists studied and sampled the vortex in what was the largest
field campaign ever to study North Pole ozone loss. With an
international team of researchers based in Kiruna, Sweden, above
the Arctic Circle, the joint study involved 350 scientists,
technicians and support personnel from the U.S., Canada, Europe,
Russia and Japan.
Dr. Edward Browell, NASA Langley's
principle investigator with the UV Differential Absorption LIDAR
(DIAL) instrument helped collect data over the ozone region and
says it is the most extensive information compiled to date.
"We provided the bigger
perspective on the ozone loss and the distribution of polar
stratospheric clouds over the whole vortex," said Browell. "Ours
was the prime instrument making the spatial extent of the ozone
loss."
The UV DIAL along with many other
instruments flew aboard NASA's DC-8 based at NASA Dryden Flight
Research Center, Edwards, Calif. The UV DIAL sent pulses of laser
light above the flying laboratory and was tuned to "see" absorption
of ozone.
"We actually sent six laser beams
above the plane," Browell added. "Different beams can get
information about the particles and the clouds through the
important part of the ozone layer or where the bulk of the ozone
resides."
 The
four-month experiment, begun in November 1999, focused on the
puzzling balance of ozone production, loss, and its movement in the
lower Arctic stratosphere from early winter to spring.
Analysis of ozone and other
atmospheric gases will show how the stratosphere's chemical
composition changed through the Arctic winter. The SOLVE campaign
hoped to identify the processes that control ozone concentrations.
In turn, scientists hope to better understand the composition of
polar stratospheric clouds (PSCs) and the chemical reactions
involved in ozone loss on the surfaces of these cloud
particles.
The polar stratosphere
temperatures were extremely low over this last winter, and PSCs can
only form in these low temperature regions. Browell added that the
PSCs' surface serves to convert chlorine gases in the upper
atmosphere from a benign or passive state to an active state that
contributes to ozone depletion.
"We're documenting the chemical
loss of ozone over the Arctic as a result of the PSCs," he said.
"So, with the Langley instrument, it helped to show how widespread
they are and the clouds' characteristics."
It was also the first time they
were allowed to fly in the coldest regions over Russia.
"Until this mission we haven't had
permission," Browell said. "But it's critical to have this
important data to study these clouds."
The DC-8 flew its first mission
over Russia's Franz Josef Land during SOLVE's first phase last
December. Another flying laboratory based at NASA Dryden, NASA's
high-flying ER-2 (a modified design of Lockheed's U-2) completed
its first science flight though Russian airspace in conjunction
with the DC-8 in January.
Browell, a NASA Langley employee
since 1974, has flown DIAL systems all over the world for 20
years.
"It was an exciting experiment,"
he added. "We got to see the whole process from start to finish,
and we pretty much nailed it. It was a very good mission and timed
just right."
- end -
For still or video images of the SOLVE project or mission
results, contact the NASA Langley Research Center, Hampton, Va., at
the phone number listed above.
For more information on atmospheric sciences
see:
http://asd-www.larc.nasa.gov/ceres/ASDceres.html
for more information on SOLVE, see:
http://cloud1.arc.nasa.gov/solve/index.html
for THESEO 2000, see: http://www.ozone-sec.ch.cam.ac.uk
or http://www.nilu.no/projects/theseo2000
A media guide for SOLVE can be downloaded
from:
http://george.arc.nasa.gov/dx/basket/factsheets/FS991103.html.
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