Thursday, November 26, 2009

The Ozone hole over Antarctica - 2009

The size of the annual ozone hole over Antarctica peaked in late September at 23.8 million square miles, slightly smaller than the North American continent, according to a news release from the NOAA in November.

That ranks as the 10th largest since satellite measurements began in 1979. Ozone over South Pole Station also reached its thinnest vertical point of the year on Sept. 26, NOAA reported.The ozone layer in the Earth’s stratosphere, between 10 and 30 kilometers above the ground, helps shield the planet from harmful ultraviolet radiation. Human-produced compounds known as chlorofluorocarbons or CFCs, release ozone-destroying chemicals into the atmosphere responsible for the depletion.

Extreme cold, ice cloud formation in the stratosphere, and a pattern of rapidly circulating air, called the polar vortex, make the ozone layer over Antarctica much more vulnerable to CFC-destruction than anywhere else on the planet.

International agreements have strictly limited the use of CFCs since the early 1990s. Scientists predict the ozone hole will recover by the end of the century.

Scientists in Antarctica, including teams from NOAA and the University of Wyoming, have been measuring atmospheric ozone since 1986.

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