Detection of extreme values variations of precipitation over Iran

The purpose of this study is to identify and detect changes in rainfall extremes as indicators of climate change in  Iran. To conduct this research daily rainfall data of 76 synoptic stations were used from 1986 to 2016. The results show that the trend of the number of days with heavy rainfall was about 7 percent of Iran's negative and 93 percent of it was not observed. The trend of successive dry days in 28% of Iran is a positive trend and 37% there is a negative trend. The wet succession days in most areas of Iran are not trendy. The trend of the total amount of rainy days is about 99% of Iran's negative range. The maximum  negative slope of Iran's annual precipitation was observed at Masjed-e-Soleiman Station with a slope of -8.26  and there is a positive trend in the Bandar-e- Anzali. The trend of very wet days is about 78 percent of Iran is negative and about 14 percent is positive and 8 percent of it is trendless. The trend of very wet days in about 70 percent of Iran is negative. The highest wet days are observed in Khorramabad with a gradient of 1.4 and the highest decreasing trend in Sarpol-e-Zahab with a gradient of 2.78. Also, in 22% of Iran's range, there is no particular trend. The trend of one-day' precipitation in about 47% of Iran's negative and in 47% is without trend and 6% of it is positive. The trend of the maximum amount of 5-day precipitation about 73% of Iran is negative and in 2% it is positive and 25% of it is without a trend. The slope of the decreasing trend in Fasa and Masjed Soleiman stations is -2.4 and -1.9 respectively