Ozone levels over the Earth's far north dipped sharply early last year when polar winds trapped nitrogen pollutants, researchers reported on Wednesday. The sun contributed to the problem, sending out a storm of particles that bombarded the Earth and helped generate some of the ozone-destroying chemicals, according to the report in Geophysical Research Letters.
Declines in ozone over the South Pole have raised concern in recent years. They were blamed on chemicals used in aerosol sprays, since those chemicals were widely banned, ozone levels have risen in the Antarctic.
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"This decline was completely unexpected," the researchers said in a statement. "The findings point out a critical need to better understand the processes occurring in the ozone layer."
Winds 32.2 kilometres above the Earth's surface became much stronger than usual, the researchers said. Those winds formed a vortex, or circle, allowing nitrogen oxide and nitrogen dioxide gasses that had formed as a mass of energetic particles bombarded the Earth solar storm in the fall of 2003 to descend and react with the ozone layer."
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http://afr.com/articles/2005/03/02/1109700517897.html