Projection of the early fall and late spring frosts under climate change condition with SDSM model in several selected stations in the mid-western Iran

In recent years, many researchers have studied change in extreme climatic events (such as the early fall and late spring frosts) due to climate change. This research is aimed to evaluate the future changes in the beginning and ending dates of frost events on the basis of the HadCM3 data under two scenarios A2 and B2, which were downscaled through the SDSM software at four selected stations in western half of Iran including Arak, Zanjan, Qazvin and Saghez. To this end, the downscaling model was calibrated based on the 40-year (1961-2001) minimum daily temperature data of four selected stations in the western half of Iran. The calibrated model, then, was employed to downscale the projected minimum daily temperature data at the stations of interest for the period 2011-2051. The first and late frost dates were extracted in three temperature thresholds of slight, moderate and severe. Results showed that the future fall frost date of Qazvin station will be later and Saghez station will be sooner in comparison to the other stations. The future spring frost date of Qazvin station will be sooner and Saghez station will be later in comparison to the other stations. In general, the findings revealed that SDSM outputs under both scenarios had no significant difference in projection of the first and late frost dates.