Chlorine monoxide, the dominant ozone-destroying chlorine molecule, and ozone were measured in the stratosphere of the Southern Hemisphere in September of 1991 and 1992 by the Microwave Limb Sounder. Strong ozone minima over Antarctica are seen on the right, corresponding to the chlorine monoxide maxima on the left.
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Small concentrations of chlorine monoxide (left globes) range from blues, through greens and yellows, and up to the higher concentrations, shown in reds and purples.
The total-column ozone measurements (right globes) are shown in violet (120 Dobson Units) through blue, green, yellow, and orange, to red (330 Dobson Units).
Chlorofluorocarbons (CFCs) are the primary source of chlorine in the stratosphere. Ozone-destroying active chlorine (e.g., chlorine monoxide) is produced by a series of photochemical reactions, including heterogeneous reactions on the surfaces of polar stratospheric cloud particles.
