The synoptic comparison of severe dust storms in the spring and summer in north of Sistan and Baluchistan province

Subject Areas : Marine Biology

S. Barkhordar ¹ (Dept. of Meteorology, Islamic Azad University, Tehran North branch)
M. Moradi ² (Atmospheric Science and Meteorological Research Center (ASMERC), Tehran)
F. Arkian ³ (Dept. of Meteorology, Islamic Azad University, Tehran North branch)

Received: 2014-08-03 Accepted : 2016-03-08 Published : 2017-08-23

Keywords: dust storm, horizontal visibility, Zabol weather station, low heat, synoptic 120 days Winds,

Abstract :

Dust storm is one of the most important climate phenomena in the east of Iran. Because the soil type of this area is fine aggregate, the appropriate wind velocity causes to rise of the particles and when the wind speed exceed than the certain threshold, suitable situation for dust and sand storms would provide. In this article to investigate the mentioned phenomenon we analyzed synoptic data from meteorological station in Zabol for the 15-years period from 1995 to 2010. To analyze the dust storm, Horizontal visibility less than 1000 m was defined as the index. Based on this definition, two of the most severe dust storms in spring and summer were chosen and by using the Synoptic data archives NCEP/ NCAR, Synoptic and dynamic conditions of the dust storms were investigated. The results showed that in the summer due to the thermal low pressure system over Pakistan accompanied by cold air advection in the North East of Iran, Causing an Intensive pressure gradient creation in the region and conditions for wind, exceed than the threshold, would be provided. In spring the a baroclinic atmospheric system with low humidity, and Relatively severe cold air advection accompanied by a active cold front, cause increases in wind speed, reducing horizontal visibility and creating dust storms in the east region of Iran.

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