Empirical model development and comparison with existing correlations

This study utilized monthly mean daily values of global solar-radiation and sunshine duration at 41 locations in Saudi Arabia and developed an empiric al correlation for the estimation of global solar radiation at locations wh ere it is not measured. The paper also presents the comparison between the present correlation and other models developed under different geographical and varied meteorological conditions. The comparisons are made using stand ard statistical tests, namely mean bias error (MBE), root mean square error (RMSE), mean percentage error (MPE), and mean absolute bias error (MABE) t ests. The errors are calculated using monthly mean daily measured and estim ated values of global solar radiation at all 41 locations. The study found that the present correlation produced the best estimates of global solar ra diation. (C) 1999 Elsevier Science Ltd. All rights reserved.