"The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is unique in its possibilities to detect polar stratospheric clouds (PSCs) since it is the first instrument with the ability to observe these clouds continuously over the polar regions especially during the polar night," Michael Hpfner of Germany's Forschungszentrum Karlsruhe GmbH said.
Using data collected by MIPAS, a German-designed instrument that observes the atmosphere in middle infrared range, Hpfner and other scientists discovered a belt of nitric acid trihydrate (NAT) PSCs developing in the polar night over Antarctica in 2003 about one month after the first PSCs, which were composed of water crystals, were detected.
There are two classifications of PSCs Type I clouds contain hydrated droplets of nitric acid and sulphuric acid, while Type II clouds consist of relatively pure water ice crystals.
The presence of NAT was detected because of MIPAS' ability to map the atmospheric concentrations of more than 20 trace gases, including ozone as well as the pollutants that attack it.
"This has been the first evidence for the existence of NAT PSCs on a large scale," Hpfner said. NAT particles, which contain three molecules of water and one molecule of nitric acid, enhance the potential for ozone destruction in polar regions.
The thinning of the ozone is caused by the presence of man-made pollutants in the atmosphere such as chlorine, originating from man-made pollutants like chlorofluorocarbons (CFCs). During the southern hemisphere winter, temperatures drop to very low levels causing the chemicals in the st
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Contact: Mariangela D'Acunto
mariangela.dacunto@esa.int
39-069-418-0856
European Space Agency
10-Apr-2006