UV-B and UV-A irradiance can be calculated from GUV measurements in a similar way as the UV-Index: as a linear combination of GUV channels (305, 313, 320, 340, and 380 nm):
UV-B (or UV-A) = a1 E305 + a2 E313 + a3 E320 + a4 E340 + a5 E380
The coefficients a1 to a5 can be determined via a multilinear regression of UV-B (or UV-A) against spectral irradiance E305 ... E380 using either data of a spectroradiometer or radiative transfer model calculations. For the coefficients provided below, we used UV spectra measured between April 2006 and July 2007 by the UV spectroradiometer at Palmer Station. From these spectra, spectral irradiance at 305, 313, 320, 340, and 380 nm were extracted and correlated against UV-B and UV-A irradiance determined by integrating the same spectra over the
We note that
Our analysis showed that UV-B and UV-A irradiance can be calculated from only one or two GUV channels with excellent accuracy. The resulting coefficients ai, and the square of the correlation coefficients, R2, are provided below. Note that spectral irradiances, Ei, have to be provided in units of µW/(cm2 nm) for the calculation to be correct. The resulting