The Evaluation of the Three Downscaling Methods in Meteorological Droughts ForecaStingunder the Effects of Climate Change

Increasing frequency and intensity of drought extremes associated with global change are a key challenge for Agriculture and water resource. In the study, Standardized Precipitation droughts Index (SPI) was calculated with different time scale and by fifth report data and three method of downscaling for Neyshabour station and were compared with together. Drought Index (SPI) was determinate for baseline period (1992-2011) and future period (2020-2039) by precipitation data. Precipitation data was determinate by use fifth report model of CANESM2 and two emissions scenarios(RCP 4.5 and 8.5) and by three downscaling method of SDSM, LARS-WG and change factor. The SPI value was determinate for four time scale equal of 3, 6, 12 and 24 months. The result showed that had a slight increases of precipitation for three downscaling method for future period. Also the value of SPI index was showed that drought intensity had more for long time scale. In competition of three downscaling method, change factor method had the value of SPI index in range of drought equal of slight to intense.