Trend analysis, frequency, amount and severity of rainfall input systems to the south and southwest of Iran.

In this research, the frequency, amount and severity of precipitation of the incoming systems to south and southwest of Iran are investigated. For this purpose, the daily precipitation data of 43 stations in Hormozgan, Bushehr, Khuzestan, Ilam, Fars, Kohkiloyeh and Boyer Ahmad provinces, Four Mahal and Bakhtiari and Lorestan were received from the Meteorological Organization of the country.For this purpose, the daily rainfall data of 43 synoptic stations of the provinces, Hormozgan, Bushehr, Khuzestan, Ilam, Fars, Kohkiluyeh and Boyer Ahmad, Chahar Mahal and Bakhtiari and Lorestan were obtained from the Meteorological Organization of the country.After the preparation of the data received and the choice of the statistical base, the initial data set and table, based on the desired index (1 mm rainfall occurrence and more, 50 percent of the station, to the condition that at least 1 in 5 mm rainfall station occurred).The Frequency of systems (annual, monthly, and sustained), annual average rainfall, and annual average rainfall of annual systems were extracted and identified;The annual frequency of systems and the average annual rainfall during the period,The monthly frequency of systems in January, March, December, April and February,The frequency of the system is 1 to 4 days and the average annual precipitation annual systems, is decreasing. But the high frequency of the November and 5-day system is incremental.In general, the frequency of systems and the amount of precipitation in the studied area is decreasing. However, the rainfall intensity of the systems is not specific, but overall it has a decreasing trend.