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Environment: Antarctic ozone hole closes early this year

Warmer stratosphere, active polar vortex help speed seasonal recovery

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A graphic from the WMO shows the progression of the Antarctic ozone hole.

By Summit Voice

FRISCO — Relatively warm stratospheric temperatures helped limit the size of this year’s Antarctic ozone hole, which disappeared completely by Nov. 10, earlier than in recent years.

Using data gathered from ground stations and weather balloons, the World Meteorological Organization said the warmer temps at an elevation of about 20 kilometers limited the formation of polar stratospheric clouds which, through a chemical chain reaction between water, nitric acid and halogenated reservoir gases cause ozone loss. In this respect, the 2012 ozone hole was similar to the one in 2010, when a sudden stratospheric warming in July and August gave rise to a smaller amount of polar stratospheric clouds than usual. Continue reading

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Remember the ozone hole? It’s back, over the North Pole

Climate change linked to abnormally cold temperatures in the Arctic stratosphere; those conditions result in regional ozone loss

These clouds composed of frozen nitric acid and sulphuric acid form when temperatures in the stratosphere at an altitude of about 20 km fall below –78 degrees Celsius. This is currently the case in vast sections of the Arctic. Although these clouds are of natural origin – in isolated cases they have been substantiated by paintings from the 18th century – they have in the meantime become a portent of imminent ozone loss due to human activity. Chemical processes on the surface of the cloud particles transform the initially harmless degradation products of anthropogenically produced chlorofluorocarbons (CFCs) into aggressive ozone-depleting substances. Consequently the ozone-depleting impact of CFCs unfolds with full force whenever it is extremely cold in the stratosphere – like at the moment over the Arctic. Photo: Markus Rex, Alfred Wegener Institute.

By Summit Voice

SUMMIT COUNTY — While ozone hole over Antarctica has slowly started to heal — thanks to concerted global action to ban chlorofluorocarbons — unusually low temperatures in the Arctic ozone layer have recently initiated massive ozone depletion at the other end of the Earth.

The Arctic appears to be heading for a record loss of this trace gas that protects the Earth’s surface against ultraviolet radiation from the sun, according to measurements from an international network of more than 30 ozone sounding stations spread all over the Arctic and Subarctic and coordinated by the Potsdam Research Unit of the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association in Germany.

“Our measurements show that at the relevant altitudes about half of the ozone that was present above the Arctic has been destroyed over the past weeks,” AWI researcher Markus Rex said in a press release. “Since the conditions leading to this unusually rapid ozone depletion continue to prevail, we expect further depletion to occur.” Continue reading

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