Polar regions, ozone depletion over

The substantial concentration of ozone in the stratosphere can be significantly depleted by comparatively small amounts of other substances. The significantly depleted ozone level in polar regions (mostly over Antarctica) is referred to as the ozone hole. 

Halogen-atom catalyzed processes are the cause of steady and continuing global ozone decline as well as superimposed massive seasonal ozone depletion observed over polar regions during late winter/spring (see contributions by P.J. Crutzen [1], this issue). 

There are indeed large ozone losses in the vortex, but all of the large-scale flow is from the tropics northward and downward. Also, because we know the seasonal phase of C02 and water over the tropical tropopause, we know that there is no communication backward from the polar regions to midlatitudes in these key months of ozone loss. Therefore, it isn t simply ozone-depleted arctic air moving back into midlatitudes. 

The most prominent instance of ozone layer destruction is the so-called Antarctic ozone hole that was first firmly established in 1985 by the British Antarctic Survey and observed with great alarm in subsequent years. This phenomenon is manifested by the appearance during the Antarctic s late winter and early spring months of September and October of severely depleted stratospheric ozone (up to 50%) over the polar region. The reasons why this occurs are related to the normal effect of NO2 in limiting Cl-atom-catalyzed destruction of ozone by combining with CIO ... 

NASA satellite image of the ozone hole which forms over the polar regions each year as a result of ozone depletion due to reactions with CFCs... 

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