Dust Source Regional Variability in Central Asia in Recent Two Decades and The Climate Linkages

Model simulations and satellite observational have presented different dust sources in Central Asia at the same period. Many investigations suggest that the climate linkages do exist in the shift of dust source in Central Asia. The particulate properties over different under surfaces and the regional variability of dust source were investigated based on CALIPSO vertical profiles and observations of dust frequency derived from surface station synoptic weather records respectively. The variation mechanisms in spring and summer were further explored combining the weather system analyses based on the reanalysis data, including ECMWF and MERRA2. Results indicated that, the main dust emission sources are Usturt Plateau, the east of Aralkum, Trans-Unguz Karakum, Central Karakum and the southeast coast of Caspian Sea. In early spring, the foremost emission sources were in the northern part when the westerlies at 500hPa prevailed. In late summer, the primary emission sources shifted to the southern part as the winds turned into northwest at 500hPa. The intensities of wind speed and dust emission in summer were weaker than that in spring. The seasonal variation of dust emissions was consistent with the drought intensity. However, the consistence disappeared when the intraseasonal variation is involved. The results of interannual and lag correlation analysis demonstrated that the Oceanic Niño Index (ONI) was significantly correlated with the dust emissions of Usturt Plateau, and the emissions of sandy desert were associated with the North Atlantic Oscillation (NAO). Those two relations were significant only in spring, while in summer, it was the eastern extension (situated to the northwest of Central Asia) of Azores High and the thermal forcing of Tibetan plateau that exhibited significant correlation with the dust emission in Central Asia. The wind fields caused by the heating of Tibetan plateau were in accordance with the aforementioned winds that accompanied the dust emission, and the eastern extension of Azores High stimulated the dust emission to shift eastward, reaching the maximum at around 61.4°E. The conclusions contribute to the meteorology research related with dust and also the decisions on environment protection.