Arctic ozone wiped out by solar storms
New Scientist
GIGANTIC solar storms destroyed nearly 60 per cent of the ozone above the Arctic during the spring of 2004.
The ozone, which shields us from harmful ultraviolet radiation, lies mostly in the lower and mid-stratosphere. Man-made chemicals such as chlorofluorocarbons (CFCs) have been mainly responsible for the depletion of the ozone layer. Now, Cora Randall of the Laboratory for Atmospheric and Space Physics at the University of Colorado at Boulder and her colleagues have used data collected from seven satellites to show that a record barrage of charged particles from the sun in October and November 2003 also destroyed large amounts of ozone. "We have never seen ozone close to this level in the northern hemisphere," says Randall.
It started when Earth's magnetic field funnelled some of the electrons from the solar storm into the upper atmosphere over the poles. The electrons ionised nitrogen molecules in that region, and the ions then combined with oxygen to form nitrogen oxides (NO and NO2) - levels of which rose dramatically towards the end of 2003. These molecules were sucked down into the stratosphere by polar vortex winds, where each one ripped apart hundreds of ozone molecules, just as CFCs do. Ozone levels remained low into July 2004 (Geophysical Research Letters, vol 32, p L05802).