Temporal variation of dust emissions in dust sources over Central Asia in recent decades and the climate linkages

Abstract

The temporal variation of dust emissions over Central Asia in recent decades and the linkages with atmospheric factors have not been well documented. This study investigated the annual and interannual variations of dust emissions in the six main dust emission regions (i.e., Sor Mertvyy Kultuk (SMK), Ustyurt Plateau (UP), Southeast of Aralkum (SA), Eastern shore of the southern Caspian (ESC), Central Karakum desert (CK), and Trans-Unguz Karakum desert (TK)), using the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) data from 1980 to 2018. The climate linkages with the variation trend were explored using reanalysis data and the climate indices from NOAA Climate Prediction Center (CPC). The results indicated that, in early spring, dust emissions are distinct in all these sources (except for ESC) due to the cold air intrusions from north, northwest, and northeast directions, and the effect of precipitation was limited by the high evaporation. Whereas in summer and/or early autumn, dust emissions were primarily in SA, ESC, CK, and TK because of the strong northeasterly winds, low vegetation, and dry soils. The overall interannual change of dust emissions in Central Asia showed that relatively larger emissions occurred during 1980–1986 and 1993–2003, especially in April. The dust emissions in SA, ESC, and TK in summer were positively correlated with the pressure gradient between northwestern Kazakhstan and Hindu Kush (NWKHKI), while those in SMK were negatively correlated with Caspian Sea High. The dust emissions in the six dust sources were highly correlated with the maximum wind speeds but showed different sensitivities to drought. The Multivariate El Niño-Southern Oscillation Index (MEI) was related to dust emissions in April over coastal Caspian-Sea areas (SMK and ESC), while those in February over the southern parts (ESC, CK, and TK) were significantly correlated with North Atlantic Oscillation/Arctic Oscillation (NAO/AO). These conclusions could contribute to the meteorology research related to dust emissions and also to the decisions made for environmental protection.