Spatial And Temporal Distribution And Transmission Patterns Of Dust Aerosols Over East Asia Based On Multi-source Satellite Remote Sensing

East Asian desert is a major global dust emissions source,with large amounts of dust being transported downstream to eastern China and even North America every year.Dust aerosols have a significant impact on regional air quality and climate change.In particular,large-scale dust storms in East Asia have attracted widespread attention due to their long-range transport and wide-scale impacts,but dust storm events are mainly concentrated in spring with the limited occurrence frequency.Previous studies have paid less attention to dust aerosol sources and transport processes in eastern China.Based on the multi-source satellite remote sensing,MERRA-2 reanalysis data,and ground sites data,this study systematically investigated the spatial and temporal distribution and transport patterns of dust aerosols over East Asia.The mixing processes of small and medium-sized dust and local pollutants were analysed in detail using dust events that occur in central China during autumn.（1）Dust transport is widespread in East Asia.The occurrence frequency of OMI satellite Ultraviolet Aerosol Index（UVAI）>1.0 indicated that dust sources in the Taklamakan and Gobi Desert are active all year round,Dust over desert areas can be transported downstream to eastern China when northwestern air currents occur.Dust transport was mainly concentrated in winter and spring,with a seasonal frequency that can exceed 30-40 days,which was the eastern China the main source of dust aerosols.（2）The vertical distribution characteristics of aerosols in East Asia were revealed based on long time series CALIPSO lidar data,and significant nighttime enhancement of aerosol optical thickness was found in eastern China;The aerosol layer top height in desert areas was about 4-6 km,and was spring>summer>autumn>winter;Clean dust was mainly concentrated in desert areas,while polluting dust dominated in downstream eastern China and there was a significant dust transport layer above the near-surface pollution layer.（3）Based on a typical dust event in autumn in central China,we studied the transport of common small and medium-sized dust and the mixing process with local pollution.mixing processes of local pollution can last for about 3-4 days;although most small to medium-sized dust transport events in autumn and winter do not cause PM₁₀ exceedances at ground level,the prevalence of dust particles has a significant impact on the regional atmospheric environment.（4）Satellite remote sensing observations have revealed significant dust impacts over the Tibetan Plateau.There are clear areas of active dust and sand in both the northern and south-western parts of the plateau,influenced by both high-altitude dust transport from the Taklamakan Desert in the north,as well as by local dust,and long-range transport from desert areas in western Asia.CALIPSO showed that dust aerosols on the Tibetan Plateau were mainly concentrated within 2 km,indicating an important contribution from local dust aerosols.