( Scientists from NASA and other agencies...)Scientists find Antarctic ozone hole to recover later than expected

Researchers from NASA, the National Oceanic and Atmospheric Administration (NOAA) and the National Center for Atmospheric Research (NCAR) have developed a new tool, a math-based computer model, to predict the timing of ozone hole recovery. Their findings will be published tomorrow in Geophysical Research Letters.

The Antarctic ozone hole is a massive loss of ozone that occurs each spring in the Southern Hemisphere. The ozone hole is caused by chlorine and bromine gases in the stratosphere, an upper layer of the atmosphere, that destroy ozone in an annually recurring process that takes place in the unique meteorological conditions of the Antarctic stratosphere. Those gases come from human-produced chemicals such as chlorofluorocarbons.

"The Antarctic ozone hole is the poster child of ozone loss in our atmosphere," said lead author Paul Newman, a research scientist at NASA's Goddard Space Flight Center, Greenbelt, Md. "Over areas that are farther from the poles like Africa or the continental U.S., the annually averaged levels of upper atmospheric ozone are only three to six percent below natural levels. But, over Antarctica, ozone is 70 percent lower in the spring. This new method allows us to more accurately estimate ozone-depleting gases over Antarctica, and how they will decrease over time, reducing the ozone hole area."

For the first time, a model combines estimates of future Antarctic chlorine and bromine levels based on current amounts as captured from NASA satellite observations, NOAA ground-level observations, NCAR airplane-based observations, with anticipated future emissions, the time it takes for the transport of those emissions into the Antarctic stratosphere, and assessments of future weather patterns over Antarctica.

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Source:NASA/Goddard Space Flight Center--EOS Project Science Office