WASHINGTON, DC, October 3, 2011 (ENS) - Earth's protective ozone layer above the Arctic was pierced by a hole of unprecedented size last winter and spring caused by a long cold period in the stratosphere, finds new research led by scientists at the National Aeronautics and Space Administration, NASA.
The hole covered 772,204 square miles (two million square kilometers) - about the size of Mexico - and allowed high levels of harmful ultraviolet radiation to strike northern Canada, Europe and Russia this spring, the researchers say.
The stratospheric ozone layer, extending from about 10 to 20 miles (15 to 35 kilometers) above the surface, protects life on Earth from the Sun's ultraviolet rays.
Ozone in Earth's stratosphere at an altitude of approximately 12 miles (20 kilometers) in mid-March 2011, near the peak of the 2011 Arctic ozone loss. (Image courtesy NASA)
To investigate the 2011 Arctic ozone loss, 29 scientists from 19 institutions in nine countries analyzed measurements, including daily global observations of trace gases and clouds from NASA's Aura and CALIPSO spacecraft, ozone measured by instrumented balloons, meteorological data and atmospheric models.
The scientists - from the United States, Germany, The Netherlands, Canada, Russia, Finland, Denmark, Japan and Spain - found that at some altitudes, the Arctic cold period lasted more than 30 days longer in 2011 than in any previously studied Arctic winter, leading to the unprecedented ozone loss.
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