Effects of global warming on the trend of daily temperature extremes in Caspian region stations

Extreme climatic events are rare phenomena that are rare in severity and frequency, and since the ecosystems and physical structures of human societies are regulated by normal climatic conditions, they can rarely prepare for the occurrence of these phenomena. Changes in the occurrence of extreme events can often have significant effects on ecosystems and society compared to changes in moderate climatic conditions. The purpose of this study is to investigate the trend of temperature furnaces in the northern strip of the country. The trend of temperature extremes in the two observation periods of 2015-1982 and the future period of 2055-2020 has been extracted. The data used in this study are the minimum and maximum recorded temperatures of the studied stations on a daily basis and for the next period, the micro-scaled output of the CanESM2 general circulation model based on 4.5RCP and 8.5RCP scenarios has been used. The results showed that the minimum and maximum daily of the studied stations will increase in the next period, which is accompanied by a steeper slope according to the 8.5RCP scenario. Relatively, Gorgan station has the highest temperature increase among the studied stations. Statistical analysis shows that in all stations and in each period of the observed and modeled period, temperature oven indices are associated with trends and changes so that cold extremes (ID icy days, TN10p cold nights FD forest days , TX10p cold days) with decreasing slopes and warm extremes (SU25 summer days, TR20 tropical nights, TN90p warm nights and TX90p warm days) face an increasing slope in both observation and future periods. The slope of some night temperature indices such as tropical nights and warm nights seems to be more intense than other indices.