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The Australian and New Zealand Association for the Advancement of Science: Another ozone hole opens up over New Zealand

The Australian and New Zealand Association for the Advancement of Science: Another ozone hole opens up over New Zealand

作者:辛幕  时间:2019-02-26 01:19:01  人气:

By STEPHANIE PAIN and IAN ANDERSON A MYSTERIOUS depletion of stratospheric ozone has been detected over New Zealand and Macquarie Island in late winter and early spring – about the same time the ozone hole forms over Antarctica. But scientists do not believe that the depletion is related to the ozone hole over Antarctica. ‘We may be looking at a new mechanism of depletion,’ said Andrew Matthews, from New Zealand’s Department of Scientific and Industrial Research. He said that the movement of air from the tropics could cause the depletion. These masses of air have a low concentration of ozone. If this really is the cause, then it may indicate a fresh shift in global circulation patterns. An unknown chemical mechanism could also be involved, said Matthews. He and scientists from Australia’s Bureau of Meteorology compared ozone readings in the months of July, August and September in 1987, 1988 and 1989 with the mean readings for the same months from 1973 to 1984. The ozone loss of about 50 Dobson units (100 Dobson units correspond to a thickness of ozone of 1 millimetre at sea level temperature and pressure) was about two to three times as great in these months in the three later years as it had been during the same months each year from 1973 to 1984. Another puzzle is that the ozone depletion detected in 1987,