MercoPress. South Atlantic News Agency

Record spring ozone layer hole forecasted

The ozone layer hole over the Antarctica began expanding in mid August and has reached ten million square kilometres, an area equivalent to Europe, according to readings from the Envisat satellite belonging to the European Space Agency.

This is considered an exceptional situation for this period of the year with only previous recordings in 1996 and 2000, and could keep expanding well into September. Meteorological alterations in different regions of the southern hemisphere can easily alter ozone levels over the pole where vortex winds are prevalent warned the European Space Agency.

Experts are convinced that the ozone layer hole will continue to expand in the coming weeks when spring arrives to the South Pole.

Winter low temperatures and darkness contribute to the formation of clouds which contain chlorine, besides nitrogen and hydrogen, a lethal component for the ozone layer.

As the polar spring arrives, the combination of returning sunlight and the presence of polar stratospheric clouds leads to the splitting of chlorine into highly ozone-reactive radicals that break ozone down into individual oxygen molecules. A single molecule of chlorine has the potential to break down thousands of molecules of ozone.

Envisat with its "Sciamachy" spectrometer keeps track of the ozone hole following on the task undertaken in the past by GOME, Global Ozone Monitoring Experiment, with another European satellite, ERS-2.

As part of the PROMOTE (Protocol Monitoring) service, the satellite results are combined with meteorological data and wind field models so that robust ozone and ultraviolet forecasts can be made. In a first for ESA, these results are being used by the World Meteorological Organisation (WMO) to compile their regularly-updated Antarctic Ozone Bulletin.

The stratospheric ozone layer that protects life on Earth from harmful ultraviolet (UV) radiation is vulnerable to the presence of certain chemicals in the atmosphere such as chlorine, originating from man-made pollutants like chlorofluorocarbons (CFCs).

Now banned under the Montreal Protocol, CFCs were once widely used in aerosol cans and refrigerators. CFCs themselves are inert, but ultraviolet radiation high in the atmosphere breaks them down into their constituent parts, which can be highly reactive with ozone.