Examine the Balance Between the Atmosphere Changes Affecting Zab Basin Storms

Storm as one of the natural disasters has affected different regions and caused great economic, social, political and environmental losses. In this paper, after defining storm threshold, data of level 500 HPa height for 40 days of storm during the period (1986-2011) were processed using an advanced factor analysis. And finally, based on the correlation matrix (variance-covariance) and Varmix rotation on the factors, major topography variation centers at 500 hPa that affect heavy storms at Zab River Basin were discovered and analyzed. The results show that, eight centers have been involved in occurrence of storms. Among these eight centers, four centers that have the highest anomalies (R>0.7) at 500 HPa height, are detectable. 1) Axis of Middle East - North Africa to Northern Russia. 2) African tropical areas-Indian Ocean. 3) North Asia-North Europe. 4) The Scandinavian region. Such changes would strengthen and deepen the axis of ridges in these regions at 500 hPa level, and consequently synoptic storm patterns are created. Meanwhile, changes in the first 500 HPa at the first center (Axis of Middle East - North Africa to Northern Russia), have the most influence on the development of storms in Zab River Basin.