The study of atmospheric movement patterns and its effect on heavy rainfalls in Iran: case study (January 6th of 1998)

Abstract

Iranian Plateau due to its specific location is at the transition point than large-scale general circulation models of the troposphere and is seating location of the extra tropical, subtropical and tropical systems. 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. the objective of this scheme is that heavy rainfall on soil and water resources is a bad influence and the study area is located in an arid region, the floods impact on the region is enormous.heavy precipitation in January 1998 to 2014 were selected. In January 1998, a special precipitation was heavy rainfall That happened in many provinces. And the reason for this day to study.the Studied regionswere provinces: Charmahal, Bushehr, Fars, Hormozgan, Khoozestan, Kohkilooye, Lorestan and Ilam In this study rainfall with greater than 30 mm considered as the criterion of days with heavy rainfall that their information was collected of synoptic and climatology stations of studied provinces.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's 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 and 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 to subsidence of cold air, rising warm air and strengthening the polar front is one of the heavy rainfall conditions too. Eastern winds cause to entering of moisture from the Indian Ocean and western winds cause to strengthen of cyclones and heavy rainfall in the region.