Canada's SCISAT satellite explains 2006 ozone-layer depletion

Longueuil, Quebec, October 6, 2006 - A surprising new study finds that high-speed winds above the northern hemisphere have a much greater impact on ozone levels than was previously thought. Scientists used data collected in 2006 by Canada's SCISAT. This satellite was launched in 2003 by the Canadian Space Agency to observe chemical processes in the ozone layer, 8 km to 50 km above the Earth's surface.

The study showed that record amounts of ozone-destroying nitrogen oxide gases descended some 30 miles to the top of Earth's stratosphere because of strong atmospheric winds. It's a process that contributed to the depletion of the ozone layer.

In February 2006, winds in the polar vortex-the massive, low-pressure winter system that confines air over the Arctic region-sped up significantly. They rivalled the strongest such winds on record and brought increased levels of nitrogen oxide to the upper stratosphere over the Arctic and the northern areas of North America and Europe. The only time more nitrogen oxide has been observed in the upper stratosphere was during winter 2003-2004, when huge solar storms bombarded the region with energy particles, and triggered a decrease of up to 60 percent in ozone molecules.

"We had already seen that when strong winds combine with solar storms more nitrogen oxide entered the stratosphere," said Dr. Peter Bernath, principal investigator of SCISAT's Atmospheric Chemical Experiment. "But the sheer quantity of nitrogen oxide making its way from the upper stratosphere down to the ozone layer last February was remarkable, and there were no solar storms at the time."

Researchers Peter Bernath and Chris Boone of the University of Waterloo, Ontario, Lynn Harvey and Cynthia Singleton of the University of Colorado at Boulder, and Janet Kozyra of the University of Michigan co-authored the paper. The article, "Enhanced NOx in 2006 linked to strong upper stratospheric Arctic vortex," was published in September in Geophysical Research Letters, a publication of the American Geophysical Union, Washington, D.C. Cora Randall of the Laboratory for Atmospheric and Space Physics at the University of Colorado led the study team. NASA and the Canadian Space Agency funded the research.

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Related Links:

Randall, C.E., V.L. Harvey, C.S. Singleton, P.F. Bernath, C.D. Boone, and J.U. Kozyra (2006), Enhanced NOx in 2006 linked to strong upper stratospheric Arctic vortex, Geophys. Res. Lett., Vol. 33, L18811, doi:10.1029/2006GL027160 (PDF).

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