1.2 Biologically effective UV-Radiation during Extreme Mini Ozone Holes

There is a strong anticorrelation between the TOC and the UV irradiance reaching the earth's surface mainly for wavelengths below 320nm.Since the biologically effective UV radiation is gained by weigthing the spectral irradiance with an action spectrum, the anticorrelation is also evident for the biologically effective UV radiation. This anitcorrelation depends strongly on the spectral shape of the action spectrum. An action spectrum which peaks in the UVB will increase the anticorrelation while an action spectrum peaking in the UVA will decrease the anticorrealtion.

The Radiation Amplification Factor (RAF) is often used to describe the impact of a change in TOC (O3) to the biologically effective UV radiation (E). E=O3^RAF

The RAF however depends (beside the action spectrum) strongly on the TOC level and solar height. In the literature mainly RAF values for mean conditions (e.g. 320DU) are given. For extreme TOC events the RAF differs considerably from such a "mean condition" values. As shown e.g. by Schmalwieser et al. (2004) the RAF for the erythemally effective UV radiation may overstep a value of 3 in the case of an extreme Ozone Mini Hole event in Winter, while it is close to 1.1 at mean conditions (320DU, solar heigth = 60).