Dust Storm Simulation Coupled With Refined CALMET Wind Field In Tarim Basin

Dust aerosol is the most important component in the atmosphere,an important link that causes the interaction of the atmosphere,the biosphere and the lithosphere,and a key link in the global material cycle and climate change.The center of the Tarim Basin is the Taklimakan Desert.It is the second largest mobile desert in the world.It is a high-incidence center for dust storms in China and a high-risk center for dust storms.It raises dust aerosols through the parasol effect,ice core effect and iron.The fertilizer effect affects regional and global climates and has become one of the hotspots for studying global change.Although the Taklimakan Desert covers an area of 330,000 square kilometers,and the meteorological observatory is limited to the oasis on the edge of the desert,the meteorological observations throughout the desert are almost blank.The uniqueness of the basin climate and the blank of large area observations make the spatial distribution of meteorological elements such as temperature,wind direction and wind speed impossible to be obtained by interpolation.The surface wind element data is missing,and the alternatives such as NCEP reanalysis or FNL analysis of wind element data are almost completely ineffective in this area of the Tarim Basin,which in turn will lead to all wind-related sands driven by reanalysis data.Dust mode fails in this area.Because the Taklimakan Desert is the high-risk center of the global dust storm,it can raise a large amount of dust aerosols to affect the regional and global climate,and carry out a refined simulation of the wind field in this area,and then use the sandstorm pattern to accurately simulate the dust storm process in the basin.To assess the amount of sandstorms,it has important scientific and practical value for the study area and global climate change.In view of the above problems,this paper attempts to correct the wind field in the Tarim Basin by using the CALMET module in the CALPUFF simulation system by using the observation data of desert aeolian landforms and meteorological wind conditions,and obtaining fine The surface wind field is coupled into the sandstorm pattern to improve the accuracy of the sandstorm process in the Tarim Basin.The main conclusions are as follows:1)Observations from 1995 to 2017 show that the most common place for sandstorms is the desert hinterland,where the most marginal oasis occurs at the southeastern end of the basin,followed by the southern Hetian-Peshan area and the Keping-Alar area in the north.The number of occurrences of sandstorms is much higher than that of sandstorms,and its spatial distribution is generally consistent with the spatial distribution of sandstorms.The high dust process has almost no dust activity in winter.The peak season of sand and dust weather during the spring-summer transition period is the highest season of sand dust weather,and the frequency of sand dust weather drops sharply from July to September.Although these characteristics are also present in the desert hinterland,the towers in the desert hinterland from July to August still maintain a very high frequency,which is related to the existence of thermal low pressure in the center of the summer basin.2)Determined the three paths of cold air entering the Tarim Basin,the East Road,the West Road and the Middle Road.When there is only the East Road,there will be weak sandstorms in the basin.The East and West Roads will appear at the same time,and moderate-intensity sandstorms will occur.Three paths of road,west road and middle road appear at the same time,and a strong sandstorm process occurs.On the three paths,the upstream Tiegan Rick,Wuqia and Aksu were selected as representative stations,and the statistical correlation between the representative station and the wind speed at the edge of the basin was established.Then,based on the surface wind direction of the desert estimated from the desert aeolian landform,the wind speed and direction of each station are obtained.When the wind directions of the two adjacent stations are opposite,according to the wind speed of the two stations,the wind direction with a small wind speed at the station is revised to a wind direction with a large wind speed.3)Using the wind speeds of the three representative stations to determine the path and intensity of cold air intrusion into the Tarim Basin,and then input the wind direction elements of the observation sites and the wind direction elements of the desert landforms,which are obtained from the statistical relationship,into the CALMET model,and then drive the CALMET model to simulate A refined surface wind field is obtained.Through the analysis of three cases of weak,medium and strong sandstorm processes,the CALMET model simulates the surface wind field in addition to the refined surface of the basin and the convergence area indicated by the horizontal divergence.Because there is no meteorological observation point in the desert,it cannot be verified,but The convergence zone of the wind field is almost identical to that observed by satellites.The surface wind field in the process of weak,medium and strong sandstorms shows completely different scenes.It is more realistic that the surface wind field is more realistic than the original desert wind accumulation.In addition,observations suggest that the desert hinterland is the high-risk center of sandstorms,but the refined surface wind field and satellite observations simulated by the CALMET model show that not all desert hinterlands are high-incidence centers,which depend on the path of cold air intrusion into the Tarim Basin..4)The sandstorm pattern coupled with CALMET's refined surface wind field can well simulate the sandstorm process in the Tarim Basin and make up for the shortcomings of the current sandstorm pattern.At the same time,the Tarim Basin is the second largest source of sand dust in the world.The accurate simulation of its sediment volume contributes to the estimation of the global dust and its understanding of climate effects.