The Role of Pressure Patterns on the Precipitation of the South Coast of Caspian Sea

Subject Areas : Geopolitic

بهلول Alijani ¹ (ندارد)
حسین Mohammadi ² (ندارد)
آتوسا Bigdeli ³ (ندارد)

Received: 2015-01-10 Accepted : 2015-01-10 Published : 2008-01-21

Keywords: Pressure Patterns and Rainfall, Caspian Sea, Coastal lands, climate of Iran, Daily Rainfall runs,

Abstract :

In order to understand the role of pressure systems on the precipitation of the Caspian coastal lands, daily precipitation data of the weather stations of the area were obtained from the Meteorological Organization of Islamic Republic of Iran for the period 1986-2003. Using Cluster Analysis the study area was divided into three distinct regions on the basis station’s precipitation variables. In each region the daily rainfall runs of 2 days length and more were determined. For each rain run a representative run was selected. For each of these selected runs the weather maps of surface and 500 hPa levels were analyzed. On the basis of this analysis the main and dominant pressure patterns of the rain days were defined. The results of the study showed that the western migratory high pressure systems are the main cause of the coastal areas precipitation. This study did not find any significant role for the ever accepted Siberian High pressure in the area’s precipitation.