Abstract
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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.
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