UV increase due to ozone loss

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The chemical depletion of ozone in the stratosphere causes an increase

of ultraviolet radiation on the ground. The UV index is a measure of

the danger of the UV radiation.  It corresponds to the

sunburn-effective solar irradiance.

This is a sample calculation [#FN1]_, how the UV index typically

changes at a certain latitude in winter and spring.  Shown are

noontime values of the UV index at clear sky for the range of the

observed ozone columns of the years 2000 and 2012 (black) and

corresponding values for a given decrease the ozone column (blue). The

selection of the two values for geographical latitude and ozone loss

can be altered.  The anthropogenically induced polar ozone depletion

takes place within the polar vortex, which in winter and spring is

well separated from the mid-latitudes.  After the breakdown of the

polar vortex (in the Northern hemisphere typically at the latest in

early April), ozone-rich air from mid-latitudes will be transported

back into the polar regions.

In contrast to the Southern hemisphere, there are typically no

significant increases to very high UV indices in polar high latitudes

in the Northern hemisphere in the relevant period until April.

These graphs show how the maximum UV index (at noontime at clear sky)

would change due to ozone depletion in the Arctic polar vortex.

.. [#FN1] The mean values and standard deviations of the ozone columns were calculated from the database of Bodeker-Scientific (http://www.bodekerscientific.com).  Calculation of the UV index for cloudless sky according to the method of Allaart et al. (Meteorological Applications, 11, 59-65, 2004)