A significant decline in ozone over the Arctic last winter was due to an increase in the size and longevity of polar stratospheric clouds, according to a group of researchers who participated in a massive, international atmospheric science campaign.
The ozone-destroying clouds are made of ice and nitric acid, said University of Colorado at Boulder Professor Owen B. Toon, one of five project scientists heading up NASA's SAGE III Ozone Loss and Validation Experiment, or SOLVE. The SOLVE project involved satellites, aircraft, balloons and ground-based instruments operated from December 1999 through March 2000 by more than 200 scientists and support staff from the United States, Canada, Europe, Russia and Japan.
Polar stratospheric clouds generally form about 13 miles above the poles when temperatures drop to minus 110 degrees Fahrenheit and below, said Toon, a professor in CU-Boulder's Laboratory for Atmospheric and Space Physics. The SOLVE campaign was staged out of Kiruna, Sweden.
In some parts of the Arctic stratosphere -- which is located from about 10 miles to 30 miles above Earth -- ozone concentrations declined as much as 60 percent from November 1999 through March 2000. The fragile stratospheric ozone layer shields life on Earth from the harmful effects of ultraviolet radiation.
Toon is the co-project scientist in charge of NASA's DC-8 aircraft that made about 25 flights over the region last winter. Six CU faculty members and four graduate students worked with scientists from several other Colorado institutions on the SOLVE campaign, including the National Oceanic and Atmospheric Administration, the National Center for Atmospheric Research and the University of Denver.
Toon will participate in a news briefing on the subject at the spring meeting of the American Geophysical Union to be held May 30 to June 3 in Washington D.C. Other panelists include Eric Jensen of NASA's Ames Research Center in Moffett Field, C
Contact: Owen.B. Toon
University of Colorado at Boulder