Study of factors affecting dust phenomenon in west of Iran

Dust is one of the destructive phenomena of climate that annually makes a lot of damage to the environment, roads, buildings and urban air. Western Province of Iran are susceptible places for frequent occurrence of dust phenomenon. For this study the data of horizontal visibility and reported dust phenomena of several meteorology stations in the western provinces were used. After determining the days with dust and their classification, we attempted to extracted maps of different levels of the meteorology International Centre from the NOAA. Finally, the maps and data of dust were analyzed in the case study. The results showed that the reduction of soil moisture reduced due to decreasing precipitation over the past decade, particularly in the north the middle east, that is feeding region's the major rivers of Mesopotamia and also, increasing frequency of the short waves and rapid with strong wind-orbital are the main reasons of storms. It appears that on strengthening subtropical high pressure on Saudi Arabia and simultaneously expanding and opening lines 588 D kamtr Intermediate levels causing increasing the speed of short waves and reduction moisture the advection from high latitudes to the south of the study area. This mechanism reduces the depth of Mediterranean descent wind conditions also triggers orbital and is weakened meridional currents. It also weakened the landing place to the Mediterranean and towards higher latitudes and raise subtropical high pressure center can be another reason for the displacement of dust to the north a source.