Geographical Research

In this study، it has been tried to test the accuracy of output and hence the model efficiency in the predictions of 24 and 48 hour precipitation forecasting by choosing different schemes be assessed. Therefore، in order to test the accuracy of model product، two conditions of rainfall precipitation and lack of rainfall precipitation were considered. Four thresholds were taken. Adaptive table and threat scores were calculated. The final results of the analysis are summarized. The results indicate that among different configurations، the model output for the two configurations of GDMYJ and KFMYJ which in both of them boundary layer scheme Mellor-Yamada-Janjic were used، are closer to the truth and their accuracy are more acceptable. Then proportion correct (PC) for the four thresholds، without precipitation (≤ 1.0)، less than or equal to 1 mm (1 ≥ and> 1 .0)، less than or equal to 10 mm (10 ≥ and> 1) and more than one، and more than 10 mm (<10) for 48 hours predictions have acceptable values such that totally about 80 percent، predicting the occurrence or non-occurrence of precipitation is done properly. Amount of H represents for two thresholds means less than 1. 0 and more than 10 mm is close to one، it means that the model for the two mentioned thresholds has higher accuracy. This quantity for the range of one tenth to a millimeter is 0.3 which indicates the relative weakness of model in this range