study of regcm3capability of the of modeling precipitation & temperature over khorasan province, case study: winters of 1991-2000

â â â  in this study, ability and skill of the nesting version of the regcm3 regional climate model in simulation of monthly and seasonal amount of precipitation and temperature using four different cumulus parameterization of grell-as, grell-fc, emanuel and kuo have been studied over khorasan area including three provinces of north khorasan, khorasan razavi and south khorasan. in this regards, 40 control runs using nnrp1 reanalysis data have been done for winter seasons of 1991-2000 over the area under study. errors of the modeled data computed by comparing with cmap precipitation data, ncep temperature data and observed data of 15 synoptic weathers stations that located inside the study area. bias and mean absolute errors were calculated monthly and seasonally. results show that among four parameterizations methods used in this research, monthly and seasonal bias of the grell-fc and grell-as with amount of +2.1 and -1mm is lower than other parameterizations scheme. smallest bias of monthly and seasonal temperature have been found in emanuel parameterization by amount of -0.8ëšc and +0.7ëšc, respectively. results of this research can be used in development of regional climate models for issuing seasonal forecast over northeast of iran.â â â