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Posts Tagged ‘stratosphere’

Low temperatures enhance ozone degradation above the Arctic

January 19, 2012 Comments off

physorg.com

March 2011: This shows strongly reduced ozone values (left, dark blue) and significantly increased concentration of chlorine monoxide (right, red) that is directly involved in ozone degradation. Credit: Figure: IMK-ASF, KIT

About a year ago, IMK scientists, together with colleagues from Oxford, detected that ozone degradation above the Arctic for the first time reached an extent comparable to that of the ozone hole above the . Then, the KIT researchers studied the mechanisms behind. Their results have now been published in the journal .

According to IMK studies, occurrence of the Arctic ozone hole was mainly due to the extraordinarily in the ozone layer that is located at about 18 km height in the stratosphere, i.e. the second layer of the earth’s atmosphere. There, originating from chlorofluorocarbons (CFC, e.g. and refrigerants) and other pollutants are converted chemically at temperatures below -78°C. These chemical conversion products attack the ozone layer and destroy it partly. One of the main statements in the study: If the trend to colder temperatures in the stratosphere observed in the past decades will continue, repeated occurrence of an Arctic ozone hole has to be expected.

The team of IMK researchers analyzed measurements of the chemical composition of the atmosphere by the MIPAS satellite instrument developed by KIT. In addition, model calculations were made to Read more…

Categories: Arctic sea Tags: , ,

Ozone layer damaged by unusually harsh winter

April 6, 2011 1 comment

independent

An image of total ozone column profile around the North Pole on March 30, 2011, developed by the Finnish Meteorological Institute using satellite and ground-based data, is seen in this handout, April 5, 2011. Satellite measurement of total ozone from OMI (Ozone Monitoring Instrument) shows a region of low ozone (blue region) above the Arctic regions. As of late March the ozone-poor region is shifted away from the pole and covers Greenland and Scandinavia. — WMO via Reuters

The stratospheric ozone layer, which shields the Earth from the Sun’s harmful ultraviolet rays, has been damaged to its greatest-ever extent over the Arctic this winter.

The protective layer of gas, which can be destroyed by reactions with industrial chemicals, has suffered a loss of about 40 per cent from the start of winter until late March, exceeding the previous seasonal loss of about 30 per cent, according to the World Meteorological Organisation (WMO).

The phenomenon is annual in the Antarctic, where after its discovery in the 1980s it came to be known as the “ozone hole“. Although CFC levels are now dropping, they remain in the atmosphere for so long that they will still be causing ozone depletion for decades in certain conditions, particularly the intense cold of the stratosphere.

Arctic ozone conditions vary more and the temperatures are always warmer than over Antarctica, where the ozone hole forms high in the stratosphere near the South Pole each winter and spring. Because of changing weather and temperatures, some Arctic winters experience almost no ozone loss – but others with exceptionally cold stratospheric conditions can occasionally lead to substantial ozone depletion.

This is what has happened over the Arctic this winter; for while at ground level the Arctic region was unusually warm, temperatures 15-20km above the Earth’s surface plummeted. WMO officials say the latest losses, which are unprecedented, were detected in Read more…

First North Pole Ozone Hole Forming?

March 23, 2011 Comments off

nationalgeographic.com


Polar stratospheric clouds over the Arctic Circle.

Spawned by strangely cold temperatures, “beautiful” clouds helped strip the Arctic atmosphere of most of its protective ozone this winter, new research shows.

The resulting zone of low-ozone air could drift as far south as New York, according to experts who warn of increased skin-cancer risk.

The stratosphere’s global blanket of ozone—about 12 miles (20 kilometers) above Earth—blocks most of the sun‘s high-frequency ultraviolet (UV) rays from hitting Earth’s surface, largely preventing sunburn and skin cancer.

But a continuing high-altitude freeze over the Arctic may have already reduced ozone to half its normal concentrations—and “an end is not in sight,” said research leader Markus Rex, a physicist for the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany.

Preliminary data from 30 ozone-monitoring stations throughout the Arctic show the Read more…