Influence Of Dust Aerosol On Temperature Field And Boundary Layer In China

Every spring,the dust weather in the northwest and northern regions of China comes into the frequent period,especially the large-scale transmission of strong dust storms,which seriously affects people’s production and life.When the direct radiation effect of dust aerosol changes the energy distribution of the earth-atmosphere system,the temperature field and boundary layer in the dust affected area respond quickly.Therefore,it is of great scientific significance to study the direct radiation effect of dust aerosol on temperature field and boundary layer.In this paper,based on ground observation data,satellite data,reanalysis data and numerical model,we quantitatively calculates the influence of direct radiation effect of dust aerosol on temperature field during daytime and nighttime,focusing on the characteristics of daytime and nighttime the influence of dust weather on the boundary layer and the mechanism of the interaction between dust aerosol,temperature field and boundary layer.The results showed that:(1)From 2000 to 2021,the frequency of dust weather in spring showed a decreasing trend,and the dust transport path was dominated by the northwest path type.Strong dust storm events occurred 32 times in the 22 years,and 53%of the strong dust storm weather processes were transmitted along the northwest path.(2)The direct radiation effect of dust aerosol leads to the cooling of surface air temperature during the day and the warming at night.The contribution rate of dust aerosol to the decrease of average temperature in daytime is 94%,and the direct radiation effect of dust aerosol at night can offset the influence of cold advection.(3)Dust aerosol affects not only the stability of daytime and nighttime atmospheric stratification but also daytime and nighttime the boundary layer height.Dust aerosols tend to make atmospheric stratification more stable during the day and less stable at night.Dust aerosols decreased the height of the boundary layer(-109 m)in the daytime,but increased the height of the boundary layer(215 m)at night.(4)In the daytime,the net direct radiative forcing of dust aerosol is-20.39,14.71and-5.69 W/m~2 at the surface,atmosphere and top of the atmosphere,respectively.The net radiative forcing of dust aerosols at night is significantly smaller than that at day,and the net direct radiative forcing of dust aerosols at night is 8.41,-10.06 and-1.65W/m~2 at the surface,atmosphere and top of the atmosphere,respectively.The most significant daytime cooling effect is-0.26℃at the height of 0-1 km.The most significant heat preservation effect at night is 0.07℃at 2-3 km altitude.When dust aerosols deposition and the height of dust layer decreased,the height with the most significant heat preservation effect at night also decreased,but the height with the most significant daytime cooling effect did not change.(5)The interaction between dust aerosol,temperature field and boundary layer is mainly affected by dust layer height,dust concentration,maintenance time and temperature advection.Before the arrival of the sand and dust process,there is a warm advection effect.When the dust weather occurs at night,the heat preservation effect of dust aerosol is superimposed on the influence of warm advection,resulting in the temperature increase range of near-surface caused by dust aerosol up to 1.55℃,resulting in the strong development of thermal instability in the middle and low layers,and further promoting the development of dust weather.