An investigation of long-term dust storms in western Iran: an insight into emission sources using HYSPLIT model and MERRA-2 data (2012–2018)

Middle East Dust storm as a nerve-racking phenomenon has suffered inhabitants particularly communities in the western and southwestern parts of Iran. The main purpose of this study was to evaluate emission sources, tracking trajectories, and synoptic analysis of dust episodes over Ilam city. HYSPLIT model, MODIS image and MERRA-2 data used to determine and confirm Ilam dust emission sources. To end this, four severe dust episodes were selected to evaluate their properties using the ERA5 data synoptic analysis and HYSPLIT. Statistically, 165 dust storms were recorded during 2012–2018 in Ilam. Spearman’s correlation coefficient of -0.66 shows the strong negative relationship between inter-annual visibility and PM10 concentration. Based on the HYSPLIT model and MODIS imageries, the origin of Ilam dust emission sources was located in Iraq, Syria, North of Saudi Arabia, East of Saudi Arabia, Jordan, and the local area (Khuzestan Province) by 63 (38%), 36 (22%), 29 (17%), 16 (10%), 15(9%), and 6 (4%) events (percent), respectively. The captured image of dust surface concentration by MERRA-2 confirmed the HYSPLIT result related to dust emission sources. The two different synoptic structures led to severe dust emissions in warm and cold periods. Low-pressure cyclones associated with the south winds on the western border of Iran can also activate the local dust emission sources particularly dried lands in Khuzestan Province in cold periods. The relative frequency of dust occurrence with 38% in Iraq and 22% in Syria indicates the predominance of northwest winds called Shamal wind, blowing from northwest to southeast.