Numerical Simulation Of The Impact Of Dust Aerosols On Meteorological Elements And Energy Balance In Northwest China

The direct radiation effect of dust has a significant influence on regional and even global climate.The frequent occurrence of dust in northwest China releases a large number of dust aerosols into the atmosphere every year.In this paper,the dust events with different intensities in northwest China in recent 7 years are studied.Firstly,different dust schemes combined with Nudging in WRF-Chem model were used to simulate the dust weather process in northwest China,and a more suitable scheme was found to improve the simulation results.Then,a typical dust event was taken as an example and the dust concentration was simulated by modifying parameters of dust emission scheme.On this basis,a case of dust events with different intensity in recent 6 years was selected for simulation.Discussed the similarities and differences of direct radiative forcing caused by dust in day and night and different regions,and then explores the difference of the influence of dust aerosol on surface energy in day and night and different regions,and then the influence on meteorological elements.The main conclusions are as follows.(1)After Nudging is combined with AFWA and Shao04,the simulation effect of dust distribution is improved,and the spatial and temporal distribution characteristics of sand and dust can be simulated by both schemes.The spatial and temporal distribution of dust and PM₁₀concentration of stations were comprehensively analyzed.The simulation effect of Shao04 scheme combined with Nudging method was closest to the actual situation.The simulation results were verified by satellite remote sensing and ground observation.The results show that WRF-Chem model can simulate the optical characteristics of dust,PM₁₀ and radiation flux distribution in northwest China.(2)Dust aerosol has a significant influence on the total surface energy,temperature and relative humidity.During the daytime,the dust decreased the surface direct radiation,total energy and temperature,and increased the surface relative humidity.The average influence of the six dust processes on the surface net direct radiation,total energy,temperature and surface relative humidity in the daytime were-6.82 W/m^-2,-3.86 W/m^-2,-0.0491?and 0.106%,respectively.At night,the dust caused the increase of surface direct radiation,total energy and temperature,and the decrease of surface relative humidity.The effects of the six dust processes on surface net direct radiation,total energy,temperature and surface relative humidity at night were 2.81 W/m^-2,3.84W/m^-2,0.0432?and-0.104%,respectively.In addition,the influence of dust on various factors in different regions is mainly related to dust concentration distribution.(3)Under the conditions of day and night and different dust concentration and dust layer height,the direct radiation effect of dust in different regions and heights is consistent,which is greater in the day than at night.Finally,the effect of the whole day is to reduce the radiation on the ground and the top of the atmosphere,and increase the radiation in the atmosphere.(4)When high dust concentration,low dust layer and dust downward transmission more heat,increase the surface of the total energy at night than during the day,causing the night dust is greater than the daytime cooling effect,heat preservation effect,in turn,affect the relative humidity,the final performance in all day to dust the ground total energy and temperature increase,reduce relative humidity on the ground.By contrast,when low dust high dust concentration,less dust downward transmission of heat,make the surface of the earth at night the increase of the total energy is less than during the day to reduce,cause cooling effect is greater than the heat preservation effect,in the night during the day,in turn,affect the relative humidity,the final performance in all day to dust the ground total energy and a decrease in temperature,relative humidity increases the surface.