Characteristics of Taklimakan dust emission and distribution: A satellite and reanalysis field perspective

Dust particles from the Taklimakan Desert can be lofted vertically up to 10km due to the unique topography and northeasterly winds associated with certain synoptic conditions. Then they can be transported horizontally to regions far downwind by westerlies. We combined data from the Multiangle Imaging Spectroradiometer (MISR) and the Cloud-Aerosol Lidar with Orthogonal Polarization to investigate the three-dimensional distribution of dust over the Taklimakan Desert and surrounding areas. During spring and summer, a dust belt with high aerosol optical depths (AOD) extends eastward from the Taklimakan Desert to the Loess Plateau along the Hexi Corridor and southward to the Tibetan Plateau. However, the dust extinction coefficients decrease rapidly from 0.340km(-1) near surface to 0.015km(-1) at 5km in spring, while the extinction values vary within 0.1000.020 between the altitudes of 1.6 and 3.5km and decrease to 0.023km(-1) at 5km in summer, indicating that dust aerosol is relatively well mixed vertically. We further used MISR daily AOD to identify high- and low-dust days and then analyzed composite difference patterns of temperature, geopotential height, and wind between high- and low-dust days. It was found that although the synoptic situations of spring and summer are quite different, there are two common features: a strong anticyclonic wind anomaly over the Taklimakan at 500hPa and an enhanced easterly wind over the Tarim Basin at 850hPa for the two seasons. These conditions are favorable for dust entrainment from the dry desert surface, vertical lofting, and horizontal transport.