On the Geomorphic, Meteorological, and Hydroclimatic Drivers of the Unusual 2018 Early Summer Salt Dust Storms in Central Asia

Abstract

AbstractA series of synoptically forced dust events, including an extreme salt storm from the Aralkum desert, stuck large parts of Central Asia during early summer 2018, causing flight cancellation, widespread haze, and salt deposition on croplands. This manuscript explores the geomorphic, meteorological, and hydroclimatic drivers of the unusual dust activity based on the three prerequisite factors of dust outbreak: sediment supply, sediment availability, and dust‐uplifting winds. Dry lake beds and lower river floodplains are identified as the source area of frequent dust episodes likely due to the abundant supply of fine‐grain sediments. Whereas, minimal dust activity was detected at the region's major sandy deserts. The salt dust storms were triggered by cold intrusion and strong postfrontal winds at the southeast flank of a rapidly developing anticyclone over western Russia which was enhanced by the Scandinavian blocking upstream. The 2018 early summer dust events in Central Asia were identified as part of spatially compounding weather hazards linked to a slow‐moving synoptic wave pattern across the Northern Hemisphere midlatitudes. Finally, the aeolian sediment availability at the dust source areas was enhanced by below‐average soil moisture and vegetation during summer 2018 linked to reduced precipitation in the preceding winter. The 2017/18 winter precipitation deficit was driven by a double‐dip, Central Pacific La Niña episode associated with large‐scale precipitation‐suppressing subsidence and enhanced moisture flux divergence over Central Asia.