Detection of the first frost of autumn and the last frost of spring with the climate change approach at Gorgan synoptic station

Changes in the history of the first frost of autumn and the last frost in the spring could be a serious threat to gardeners and farmers. The purpose of this study is to know how this change will be in the future period (2015-2068) compared to the base period (1961-2014) at Gorgan Station. For this purpose, daily data of the Gorgan Minimum Temperature Station was obtained at the observation period from the Golestan Meteorological Office. Then NCEP data, CanESM_RCP_26, RCP_45, RCP 85 were downloaded from Canada's Climate Change site, and using SDSM software, the minimum temperature data for the next period was generated for the three scenarios. Then, the date of the beginning and the end of the glacial to date of Julius was calculated and fitted with SMADA software with different statistical distributions and, using more suitable distributions, the probability of occurrence of freezing days was calculated. The results of this study indicate that the glacial period in the observation period is 75 days. it is also 46 days for the upcoming period in the optimistic scenario. It includes 39 days in the intermediate period and 31 days in the pessimistic scenario, which results in a significant decrease in the duration of the ice period and the increase of the period Growth of plants in the course of the future, which requires more vigilance of planners to deal with the destructive effects of climate change.