Transport routes and potential source regions of the Middle Eastern dust over Ahvaz during 2005–2017

Abstract Ahvaz is among the most polluted cities in the world in terms of particulate matter (PM) concentration. It is a prevailingly vulnerable city to the dust storms intrusion experiencing nearly 98 dusty days per year. The main aim of this study is to determine the transport pathways of dust particles reaching Ahvaz and investigate the dust sources that potentially contribute to dust loading over this city. To this end, temporal and spatial characteristics of Ahvaz dusty days, with a focus on associated air parcel trajectories are investigated in tandem with station observation, potential source contribution function (PSCF) and aerosol optical depth (AOD). Four main dust corridors were identified, based on the trajectory results; one northwesterly and two westerly routes, passing mainly over Tigris Euphrates Plain and Mesopotamian marshlands before hitting Ahvaz. These transport routes are associated with Shamal winds and are active all year long, especially in the summer. Another dust corridor influencing Ahvaz is a southerly route related to the prefrontal dust-storm mechanism. This corridor is active mainly in spring and winter and lifts the dust from Zubair Desert, Ad Dahna Desert and arid land of southern Khuzestan Plain. The forward calculation, PSCF and AOD analysis are consistent with backward air masses trajectory results and showed that eastern Syria, central and southeastern Iraq, and northwest of Ahvaz are the primary sources for dust affecting Ahvaz. Other intense dust sources are located in the south of Ahvaz including the eastern coastal zone of the Arabian Peninsula, southern Iraq, and southeast of Ahvaz.