The Clarification of Monthly Precipitation Fluctuations in Ahar Station in relation to the Tele-connection Patterns

Subject Areas : Geopolitic

Ali Mohammad  Khorshiddoust ¹ (ندارد)
Yousef  Ghavidel Rahimi ² (ندارد)

Received: 2014-11-29 Accepted : 2014-11-29 Published : 2009-01-20

Keywords: Monthly Precipitation, wet and dry periods, Man-Kendal test, Teleconnection&#x0D, &#x0D, Patterns, Ahar,

Abstract :

Authors have studied the precipitation fluctuations and rainfall changes inAhar synoptic station in this paper, applying long term monthly records for the47 year period (1960-2006). Results of using Man-Kendal test indicatesignificant correlation between precipitation changes and tele-connectionpatterns in the study area. With regard to this matter, the relationship of autumnprecipitation with El-Nino atmospheric-oceanic pattern (so-called ENSO) duringwarm phase increases precipitation and the same linkages with La-Nina duringcold phases enhances droughts. The correlation of winter precipitation with teleconnectionpatterns of Northern Atlantic and Arctic Ocean has been alsosignificant in such a way that during the North Atlantic negative phases themagnitude of incoming cyclones to the area creates higher rates and on the otherhand, in positive phase causes a decrease in precipitation due to the dominanceof Azure Anticyclone. Testing of Standardized Precipitation Indexes (SPI) forevaluating monthly wet and dry periods also indicates that the occasionaloccurrence of drought periods in the area is irreversible. The independence ofmonthly wet and dry periods is also one of the main results of this study.