CORRELATIONS FOR DIRECT NORMAL AND GLOBAL HORIZONTAL IRRADIATION ON A FRENCH MEDITERRANEAN SITE

The purpose of this study is to establish some correlations on direct normal and global horizontal irradiation for a mediterranean site. The correlations have been developed for monthly mean values, daily and hourly values of irradiation data. We have used linear or polynomial regressions between energetical ratio and sunshine duration. For the monthly means and the daily values, the ratio I/I(M) fits very well the sunshine duration while, for hourly values, we express I(h)/I(o,h) as a function of H(h)/H(o,h). In all cases, these correlations are, for this mediterranean site, in good accordance with experimental data. Nevertheless, a study for other locations has to be developed.