Jos van Geffen, Ronald van der A, Michiel van Weele, Marc Allaart and Henk Eskes
in: Proceedings of the ENVISAT & ERS Symposium, 6-10 September 2004,
Salzburg, Austria, ESA publication SP-572, 2005 (CD-ROM).
Most of the UV radiation reaching the surface is therefore UV-A. Due to the higher energy levels of UV-B, however, the UV-B component has more effect on flora and fauna than UV-A. An action spectrum is a parameter function which describes the relative effect of energy at different wavelengths in producing a certain biological response. These effects may be at a molecular level, such as DNA damage, or at the level of the whole organism, such as plant growth. An action spectrum is used as a "weighting function" for the UV spectrum in an integration of the monochromatic UV irradiance.
|Figure 1. Action spectra of the susceptibility of the human skin to erythema (sunburn) and of generalised DNA damage due to UV radiation. The erythemal UV index is an integration between 280 and 400 nm of the UV irradiance at ground level, weighted with the erythemal action spectrum. The DNA-damage UV index is an integration between 256 and 370 nm of the UV irradiance at ground level, weighted with the DNA-damage action spectrum.|
For the TEMIS data service the two action spectra illustrated in Fig. 1 are used:
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