Hana Etemadi

Extreme rainfall in southwestern Iran annually leads to considerable Bnancial and human losses. Reports over several years show different levels of damage caused by these events. This study aims to identify and investigate changes in the spatial patterns of systems that generate extreme rainfall in southwestern Iran. We utilized the maximum 24-hr precipitation from seven synoptic stations in southwestern Iran from 1971 to 2020. The principal component analysis technique was utilized on geopotential height data at 500 hpa to identify spatial patterns of precipitation. The data was collected from 5 to 60N and 10 to 70E that were received from the NCEP/NCAR reanalysis dataset. The study period was divided into two based on the identiBed change point by the Pettitt test, and according to the results, the Brst climatic period in southwestern Iran had nine sources or components of extreme rainfall. In comparison, in the second period, they had eight sources of extreme rainfall. The most important source of extreme rainfall for both periods and the Brst source of the second period are located at 15 north latitude over the Indian Ocean, the Arabian Sea, the southern Red Sea, the Gulf of Aden, and certain areas in the eastern tropical regions of Africa.