مخاطرات محیط طبیعی (Sep 2019)
Investigation on the synoptic pattern of pervasive dust in the warm period of Khuzestan province
Abstract
Statistical analysis shows that the long-term occurrence of dust Khuzestan province last 60 years has been faced with the phenomenon of dust. However, dust storms with coverage of more than 50 percent and minimum 2-day duration over the past two decades have become an uninvited guest. Two conditions for the occurrence of dust storms are: the presence of dust, the presence of substrates and the presence of fine particles with a small diameter and a large volume of dust forming the source; and the another synoptic-dynamic conditions as the driving force and the transfer of dust particles from the source regions to other areas. In this regard, the aim of this study is to analyze the general pattern of dust in Khuzestan province in the warm period of the year. For this purpose, data from 20 synoptic stations from the Meteorological Organization have been extracted. Then, by performing cluster analysis, identification of effective patterns on Khuzestan dust has been investigated. The results showed that five patterns were identified in determining the patterns of dust storms in the warm year, including 1) Gang low pressure thermal. 2) Gang Low-pressure, low-pressure Eastern Europe, high-pressure North-East Europe. 3) Gang Low pressure, high pressure in Europe. 4) The massive pressure of Europe, the high pressure of Kazakhstan. 5) Polar warhead high pressure, low pressure, Iceland low pressure. The results showed that the synchronous mechanisms of the dust occurrence in the first to fourth patterns, Gang low pressure thermal, which is formed during the hot season of the year with extreme warmth and heat in southern Asia, played a major role in the dust situation on Khuzestan. By placing high strength Azores in the middle of the atmosphere, the pressure difference conditions between the two high pressure and low-pressure centers have accelerated the flow velocity from higher levels to the lower levels of the atmosphere. Consequently, in conditions of lack of moisture on Khuzestan and through the passage of compressive systems from the ground and areas susceptible to dusty, dust was transported to the Khuzestan area.
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