A Study Of Dust-source Interactions In East Asia Based On Mega-dust Event

East Asia is an important source area for dust storms in the world,and has an important impact on dust and sand in the Asia-Pacific region and even globally.It is important to assess the risk of cross-border dust and sand in East Asia to the ecological environment of China,and to build an ecological barrier in the north of China,and to co-exist with other countries along the northern route of the"Belt and Road".In this study,the WRF-chem model with optimised parameters is coupled with the Shao04 sand initiation scheme,and a combination of numerical simulation,remote sensing and statistical analysis is used to numerically simulate the dust and sand process in East Asia for four consecutive years from spring 2018 to 2021,The main studies are:（i）the distribution of dust sources and dust balance in East Asia;（ii）the weather processes and environmental impacts of mega dust events in East Asia;and（iii）the interaction of dust sources in East Asia based on mega dust events.The main findings are as follows.The main sources of sand and dust in East Asia are the Taklamakan and Gurbantunggut deserts in Xinjiang,the Qaidam Basin in Qinghai,the Hexi Corridor in Gansu and the arid areas including the Badangilin and Tengri deserts,the Mawusu and Hunsandak sands in central and western Inner Mongolia;outside China,the sources of sand and dust are the Gobi in southern Mongolia.The above areas are also high value areas for sand and dust release and deposition.There is a dynamic balance between sand and dust emissions and deposition,with the extent of the deposition zone spreading over almost the whole of East Asia and the net expenditure zone corresponding to the sand and dust source zone.2021 the net expenditure zone for sand and dust is significantly higher in Mongolia than in the other three years.The East Asian mega dust event was mainly influenced by a high altitude low pressure trough and a cold front on the ground.The further strengthening of the low pressure trough to form and strongly develop a Mongolian cyclone was the driving cause of the mega dust event.During the occurrence of the mega dust event,the PM₁₀and PM_2.5generated by the wind field were spread in two branches centred on southern Mongolia and western Inner Mongolia as well as the Hexi Corridor and Qinghai region,one affecting Xinjiang in a southwesterly direction,and also forming a zone of high PM₁₀and PM_2.5mass concentration due to the rising sand there,with PM₁₀and PM_2.5in western Inner Mongolia,northern Gansu and northwest Qinghai mass concentration reached more than 20,000μg/m~3;the other one affected Shaanxi,Shanxi,Hebei,Beijing and other places in the southeast direction,and also affected the eastern coastal areas,and also affected the Bohai Sea and the Yellow Sea waters.Sand and dust aerosols achieve cross-regional transport to have a significant impact on dust and sand weather in northern China.The most severe offshore source of sand affecting northern China during the East Asian Very Large Sand and Dust Event was Mongolia.During the Very Large Dust Event,dust aerosols generated in southern Mongolia moved across the border to the downwind region,making the western part of Inner Mongolia in China a high dust load area,while at the same time,connecting with the high dust load area in Xinjiang and expanding eastwards across the entire northern region of China.Cross-border dust deposition in China can reach up to 30 g/m~2or more.This study takes the East Asian region as a whole and reveals the interactions and compounding effects of different dust and sand source areas on the Mongolian Plateau from the perspective of symbiotic coexistence between countries along the northern route of the Belt and Road,providing scientific support for ecological restoration and construction in the East Asian region.