The global and UV-B radiation over Egypt

Abstract

This work studies the relation between UV-B radiation and global radiation over Egypt. The relationships between the global solar radiation and UV-B radiation at four stations in Egypt have been studied, and linear empirical formulas for estimating UV-B from global radiation at these stations has been deduced. The deduced equations were applied to calculate the UV-B radiation for other stations where measurements were unavailable, using records of global radiation at these stations. Because of the periodicity of variations in solar radiation, global and UV-B radiation, the non-dimensional values are expanded in Fourier series. Fourier coefficients were determined by using measured global solar radiation data of the selected stations. These coefficients were used to calculate UV-B radiation based on global solar radiation for the same stations. A comparison between observed and calculated UV-B radiation arising from the two methods of estimation is presented. The comparison showed a good agreement between the observed and estimated UV-B radiation. The application of linear regression method to calculate solar radiation for other stations where UV-B radiation measurements were unavailable was better than Fourier coefficients method.