Study of Sever Dust Episodes in Isfahan, During the Period 2000-2011

The largest desert in the world is in the West Asia that due to its climatic and atmospheric conditions, has the potential to produce sever dusts. In recent years, in central provinces of Iran within the desert, including Isfahan the frequency, severity and extent of dust storms have increased, and due to population and resources at risk, the vulnerability to the phenomenon has been greatly increased. Throughout this study, it is attempted to determine characteristics of effective atmospheric circulation patterns and main dust emission sources based on meteorological information including: weather charts, visibility, AQI, backward trajectory technique and outputs of a Regional Dust Atmospheric Model. A main goal of this investigation is determining large-scale dominant weather conditions and main dust sources that cause severe air pollution episodes over Isfahan area during the period of 2000-2011. Surveys show that in recent years, frequency, intensity and extent of Dust events in the region have increased. Changes of pressure patterns are seasonally, so dust sources are variable in a year. Therefore, in late winter to spring months (March to May), based on the location and development of low-pressure systems associated with the upper and Mediterranean trough, the main effective dust sources on  producing high polluted episodes in Isfahan, are as follows: North East Africa, Northern Saudi Arabia, Jordan, Southern Iraq, Kuwait and some parts of Khuzestan area. From June to August, the Mediterranean trough is very weak compared to previous months, but it can still play a significant role in dust formation in the west Asia.  Moreover, widespread dam buildings in the south of Turkey and North of Syria and Iraq, cause development and expansion of dust sources in north east Syria and north Iraq (especially Mesopotamia region).