International focus on Antarctic ozone hole

Nacreous clouds at Mawson after sunset.
Nacreous clouds at Mawson after sunset on 28 August 2008. (Photo: Peter Tsimnadis)
Nacreous clouds at Davis after sunsetMulti-day measurements of cloud properties by the Davis LIDARVertical profiles of ozone above Davis obtained from Bureau of Meteorology balloon measurements by Fiona Gray and Greg Stone. The ozone measurements are an important part of the polar stratospheric cloud study, helping to identify at what heights ozone isDavis LIDAR in operation. The laser beam is passing through thin cloud.

16 September 2008

As expected, an ozone hole has developed over Antarctica this austral spring. The amount of ozone that has been removed from the polar stratosphere is large, but not likely to be of record proportions. This is due to the combined effects of near-average temperatures over Antarctica and international controls on ozone depleting substances.

In Antarctica, scientific research on the processes responsible for the development of the ozone hole continues. An international scientific team from Australia (comprising the Australian Antarctic Division and Bureau of Meteorology), France (University of Paris), Italy (National Research Council) and the United States (NASA) is using sophisticated laser remote sensing instruments to help understand the growth of tenuous high-altitude clouds that initiate ozone destruction.

LIDAR (Light Detection and Ranging) instruments at Australia's Davis station as well as Dumont d'Urville and McMurdo stations are working in concert with similar remote sensing equipment on NASA's CALIPSO satellite to investigate the evolution of icy cloud particles as they circulate in the Antarctic stratosphere.

These clouds, occurring approximately 10 km and higher above the surface of the earth, are termed polar stratospheric clouds, forming only in the polar winter at more than twice the height of normal 'weather' clouds. It is the particles in these clouds that initiate chemical changes in the atmosphere that ultimately leads to the formation of the ozone hole.

This work is aimed at understanding the connection between polar stratospheric clouds and ozone destruction for the improvement of long-term climate models.

Since 1995, September 16 has been internationally celebrated as World Ozone Day. On this day in 1987, the landmark international treaty to protect Earth's ozone layer known as the Montreal Protocol was signed. The Montreal Protocol is a global agreement to limit the production and release of certain man-made substances which cause harmful effects to the protective blanket of ozone in the stratosphere.

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