عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In this research, we have used from Phasic sets theory for seasonal rainfall forecasting from Dec to May in Razavi Khorasan, North Khorasan and South Khorasan Provinces. This method includes three steps. In the first step, relationships between synoptical patterns variation including Sea Level Pressure (SLP), Sea Surface Temperature (SST), Sea Surface Pressure Difference (DSLP), Sea Surface Temperature (DSSt), 1000 millibar Surface, Air Temperature at 850 hpa, Geopotential Height at 500 hpa and Relative Humidity at 300 hpa with average precipitation with average precipitation are investigated. In the second step, model was calibrated from1970 to 1992. Sensitiveness analysis is used for obtaining the best phasic rules structure and membership functions. In final step, rainfall prediction is performed from 1993 to 2002. Results showed that phasic sets theory can successfully predict amount of the rainfall.