LAUSR

In recent years, fluctuations in precipitation have caused many environmental problems in Iran; understanding the reasons of these changes is essential for sustainable development planning. Mid-latitude cyclones play a significant role in providing precipitation over Iran. In the current research, cyclone centers were defined based on two features; on the investigation point, the geopotential height is minimum compared with the eight neighbors and the weighted average of the geopotential heights on the investigation point and the eight neighbors is at least 100 geopotential meter per 1000 km. Geopotential heights and the sea level pressure data during the period of 1986–2013 for spatial dimensions, 10 to 60 degrees of north latitude and − 40 to 80 degrees of east longitude, were taken from the American National Center for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR). Data review revealed that there is a northward shift in cyclone routes associated with precipitation for the country. Moreover, the cyclones entering from the eastern Mediterranean have been reduced. Global warming and changes in the path of storm tracks can be regarded as possible reasons behind the observed changes in precipitation in Iran. In response to the shifts in cyclonic routes entering Iran, changes in precipitation have also occurred. These reductions in precipitation may continue, at least, over foreseeable future.