تحلیل روند وقوع رخدادهای فرین اقلیمی در دوره تاریخی در شمال غرب ایران

Due to the catastrophic environmental and economic-social consequences, they are of interest to the general public, the government, and academic societies. This research aims to investigate the conditions of extreme temperature and precipitation events in the North West of Iran during its historical periods. The data used in this research include the daily rainfall and temperature data of 32 synoptic stations of the National Meteorological Organization during a common statistical period of 30 years. A set of 26 Extreme precipitation and air temperature indices recommended by the CCL/CLIVAR expert group were calculated for both historical and future periods using the MATLAB software environment. Examination of the temporal changes in the occurrence of extreme hot air temperature indices during the period 1988-2017 in the North West of Iran using the Mann-Kendall trend test showed that for most stations the general trend of the hot indices, such as hot nights, hot days, number of summer days, and the number of tropical nights is increasing. On the other hand, the temporal changes in the occurrence of cold indices showed that for most stations, the general trend of cold indices such as cold days, cold nights, and the number of frost days is decreasing. Therefore, the main and important point that can be drawn from the general review of the hot and cold extremes indicators in the North West of Iran is the dominance of the warming trend in the statistical period and the climatic movement of the country towards dryer and warmer climates