Investigation on North Sea-Caspian Teleconnection Pattern Effect on Autumn Rainfall Fluctuations in West and Northwest Regions of Iran

In this research the relationship between autumn precipitation rate in north west and western region stations of Iran and north Caspian sea teleconnection pattern in a time period of 29 years (1977-2005) have been calculated and analyzed. Results of the Pearson correlation analysis between the Northern Caspian sea pattern (NCP) index and North West and western regions autumn precipitation rates showed that in Positive phase of NCP autumn rainfall is increased from normal limit and in negative phase the rainfall is decreased. A relatively good linking between the northwest and west regions’ fall rainfalls with NCP was calculated. The signficance coefficient was calculated 0. 31 for autumn long term mean rainfall of studied stations. The monthly correlation analyzes calculated indicated the highest correlation between monthly rainfall of stations and the NCP in December with an 0. 52 correlation coefficient. Results also showed that Khoy station was affected more from NCP. This study established that In addition to the ENSO، common pattern of the effects on the autumn rainfall was previously approved and new NCP also affected rainfall fluctuations and autumn wet and dry spells occurrences in northwest and west regions of Iran.