A study on weather patterns and dust sources associated with sever dust events in the summer in the south west of Iran

Dust as one atmospheric phenomenon has many important effects on environment, health, economy and social fields for entering dust particles into the atmosphere. Iran and western neighboring counties are located in the arid and semiarid belt of the world, where frequency of sever dust events, especially in south west Iran, has increased in recent years. In this paper, we investigated how this event is produced and reached to Ahwaz using observations and weather data of the period 1968-2008 in selected summer month, based on sea level, 850hpa and 500hpa weather charts, surface wind field in the start and end days of dust occurrence in Ahwaz station. The results showed that in this period, dust events by high strength and frequency were occurred in July in Ahwaz, and the synoptic patterns that produce majority of severe dust over Ahwaz are Persian Gulf thermal trough extends to the north west of Iraq and European ridge extends over Black Sea and large parts of Turkey by passing waves of middle level Mediterranean trough north west of Iraq and east of Syria. Dust sources in northwest of Iraq and east of Syria have a major role in sever dust events in summer in south west of Iran.