Study Pressure Fields Affecting Cyclone Rainfall: Case Study of Iran

Abstract

The aim of this study is the synoptic analysis of the atmospheric conditions concurrent with the heavy precipitations of Lorestan, Fars and Hormozgan provinces and determination of the temporal and spatial distribution of them. Requested atmospheric data for this research was taken from databases related to the National Organization of Atmosphere and Oceanology of United States. More maps of the site were taken. Then the earth surface, 500,700 and 850 Hecto Pascal maps, orbital and meridional winds, earth temperature of earth surface and top of the atmosphere were prepared in Grads software and some of maps were drawn in GIS software. The following results were obtained: On the earth surface map, the main controller role is with the Siberian high-pressure, the Azores’s dynamic high-pressure and integrated mode of the Sudan and the Mediterranean low-pressure systems. The main controller role in high levels is with the high altitude center of Azores in the back of the system, the high altitude center of Arabia in the front of the system and deep traffic of North Africa. Another important factor is the moisture mixture of Mediterranean Sea, Red Sea, Persian Gulf, Oman Sea and Indian Ocean. Air rise factor with enhancing meridional winds that causes subsidence of cold air, rising warm air and strengthening the polar front is one of the heavy rainfall conditions too. Eastern winds cause entering of moisture from the Indian Ocean and western winds cause strengthening of cyclones and heavy rainfall in the region.