Correlation of global solar radiation with common geographical and meteorological parameters for Damascus province, Syria

In this study, the effect of geographical and meteorological parameters on the monthly mean daily global solar radiation in Damascus was investigated. With measured data of global solar radiation and the relevant data of astronomical, geographical, geometrical and meteorological parameters for Damascus province, an attempt has been made to correlate the monthly mean daily global solar radiation on a horizontal surface with seven different variables; mean daily extraterrestrial solar radiation intensity I¯0, average daily ratio of sunshine duration n¯/N¯, mean daily relative humidity ϕ¯, mean daily maximum air temperature ϑ¯max, mean daily maximum dew point temperature ϑ¯d,max, mean daily atmospheric pressure P¯ and sine of the solar declination angle sin δ.A new multiple regression relation giving accurate estimates of monthly mean daily global solar radiation on a horizontal surface was suggested. It has a high coefficient of correlation R = 0.9915. The results showed that the suggested model can estimate the global solar radiation within relative errors e of −6.37% and 8.27%. The values of MBD (0.1 W/m2) and also RMSD (229 W/m2) are within acceptable ranges.The global solar radiation intensity values produced by this approach can be used in the design and estimation of the performance of solar applications. It is believed that the model developed in this work is applicable for estimating the monthly mean daily global solar radiation on a horizontal surface at any site in Damascus province, Syria.