Saviz Sehat Kashani - Phd Student of Department of Meteorology, Science and Research Branch, Islamic Azad University, Tehran, Iran
G.Ali Kamali - Associate Professor of Department of Meteorology, Science and Research Branch, Islamic Azad University, Tehran,
Majid Vazifedoust - Assistant Professor of Department of Water Engineering, University of Guilan, Rasht, Iran
Abbasali A. Bidokhti

Dust events in Iran as a result of the semiarid climate, its location in the global dust belt and neighboring the deserts of Arabian countries occur frequently. In recent years the intensity of dust phenomenon has been increased most especially in west and south west of Iran. In this paper the behavior of dust events is evaluated by applying 3 hourly intervals dust records of 35 national synoptic meteorological stations in west and south west of Iran over the period 2000-2009. Moreover the categorization of dust frequency has been done according to visibility reduction for the region and the relation of seasonal variations of blowing dust activities and strong winds velocity has been evaluated. This study reveals the important role of dust frequency long term variability as an index for a more advantageously interpretation of climate change in the region

dust, visibility, annual variations, seasonal variations, intensity