Assessment of the dust sources over Central and Southwest Asia with emphasis on the Sistan dust storms

¹ Department of Desert and Arid Zones Management, Ferdowsi University of Mashhad, Mashhad, Iran
² Institute for Environmental Research and Sustainable Development, National Observatory of Athens, 11810 Athens, Greece

^* Corresponding author: a.rashki@um.ac.ir

Abstract

Central and Southwest (SW) Asia are usually suffered by dust events of various intensity due to extended arid/desert regions and, therefore, the statistical evaluation of the dust activity and sources over the region has received an increasing interest. This study analyses the characteristics of the dust events and their sources over the Central and Southwest Asia from 2002 to 2018, based on meteorological observations at stations in Turkmenistan, Uzbekistan, Iran, Afghanistan and Pakistan, combined with Aerosol Optical Depth (AOD) at 10 km × 10 km derived from MODIS and a new 1-km high resolution algorithm. The dust events are classified based on visibility recordings and WMO codes, as dusty days (vis<10 km) and dust storms for visibility below 1 km. In general, the highest frequency of the dust storms is observed in the Sistan Basin, Iran and around the deserts of southern Afghanistan, while the dust-plume pathways have a distinct north-to-south pattern, from Central Asia to SW Asia and the Arabian Sea. Trend analysis in the Deep Blue MODIS AOD retrievals shows positive AOD trends over large parts of the Central Asia and negative over the Southwest Asia and Sistan. High resolution (1-km) AODs indicated that some parts of the Hamoun ephemeral lakes and the eastern part of the Sistan basin are the most active hotspot areas for dust emissions.