The Relationship between Synoptic Systems Influencing Heavy Rainfall in the Northern Low Rainfall Region

In this study، heavy rainfall of northern low rainfall region has been analyzed using environmental to circulation approach. In order to analyze these types of rains، Asfezari rain data base is used. A base with daily ranfall includes 15992 days، from 1340. 1. 1 to 1383. 1437 daily precipitation maps of northern low rainfall region were created using Kriging method. Mean daily precipitation data for this station has been used. Spatial resolution of these maps were 18 Km*18 Km. So 1406 pixels cover the northern low rainfall region and temporal and spatial behavior of precipitation could be represented by a 1406*362 matrix. We selected 100 days of the heavy rainfall from IRIMO data base. A cluster analysis was applied on this matrix and four different circulation patterns were actived. As a result، 100 occurrences of broad and heavy rainfall have been assimilated according to the sea level pressure، humidiy flux convergensy، stream function and front function exorbitance. Spatial configuration of these patterns showed that the main reason of these rainfalls had been the siberian and Black Sea unticyclones، troughs of Red Sea and Persian Gulf.