Investigation of Aerosol Optical Depth Index (AOD) in dust events over Southwestern of Iran

Desert dust is an important risk factor to human health in the southwestern provinces of Iran. This study is an attempt to highlight the relationship between changes in optical depth values extracted from the Deep Blue algorithm with the frequency of dust events in meteorological ground stations which is located in seven provinces of Ilam, Lorestan, Chaharmahal and Bakhtiari, Kohgiluyeh and Boyer-Ahmad, Khuzestan, Bushehr, and Fars For this purpose, the number of days with dust and daily data of dust events, and daily horizontal visibility were obtained from 45 meteorological stations in the fifty-year period (1966 to 2016) and analyzed. The results showed that the average annual number of days with dust increased after 2000. This figure is estimated at 82.3 days in the first decade of the trend, 46.3 days in the second decade of the trend, 84.6 days in the third decade of the trend, and 71/1 days in the whole thirty-year trend. The most severe dust conditions during the period under review were 2009 and the lowest dust conditions were in 1994. In order to verify, the AOD product was compared with the frequency of severe dust events of the Meteorological Organization. There was a perfect agreement between the temporal and spatial distribution of the dust concentration in AOD images and the temporal and spatial distribution of the frequency of dust events at meteorological ground stations. The highest annual average AOD was fully consistent with severe dust events in 2008 and 2009, as well as the most severe dust events in the summer.