Aerosol Optical Properties And Radiative Effects Of Haze Layers In North China Plain

Aerosol vertical distribution characteristics are the key factors for estimating direct radiative forcing of aerosols.Existing studies rarely use ground-based and satellite remote sensing data to directly estimate aerosol direct radiative forcing profiles.This article uses North China Plain as the study area and then comprehensively analyzes the temporal and spatial distribution of aerosol optical properties from the point,surface and vertical angles.At the same time,under the constraints of ground-based remote sensing data,the vertical profiles of aerosol direct radiative forcing and heating rates of haze layers are obtained by using satellite remote sensing data,and their vertical distribution characteristics are analyzed.The main conclusions are as follows:1)There are significant seasonal differences in aerosol optical characteristics.In summer,the aerosol optical depth is the largest with the smallest particles,strongest scattering ability,the dominant of the fine mode particles and more anthropogenic pollution aerosols.In spring,the aerosol particles are the largest with the weakest scattering ability.At the same time,aerosols consist largely of the coarse mode particles with a large amount of dust.The regional distribution center of aerosol optical depth is generally low in the north and high in the south.The high value area is in the south of North China Plain.The spatial distribution of aerosol optical depth remains unchanged,but the value of aerosol optical depth varies with time in each region.Aerosols are mostly concentrated in 0-3 km,and there is a high value center at the 0.4 km.Aerosol content is low in 3-5 km,and the smallest above 5 km.2)The accuracy of the SBDART radiative transfer model is relatively high.The error of estimated aerosol direct radiative forcing is very small.The absolute aerosol direct radiative forcing increases with aerosol optical depth.With the increase of single scattering albedo,the absolute aerosol direct radiative forcing efficiency decreases in the surface and atmosphere,and reverses at the top of the atmosphere.When the extinction ability is the same,the absorption aerosol has a greater attenuation effect on the shortwave solar light than the scattering aerosol.3)The daily direct aerosol radiative forcing ranges at the top of the atmosphere,the surface and the atmosphere are-43.94 W/m2 to-88.44 W/m2,-74.03 W/m2 to-225.86 W/m2,and 30.08 W/m2 to 137.43 W/m2,respectively.Aerosol has a cooling effect on the surface and atmosphere and a warming effect on the earth and atmosphere systems.4)The vertical distribution characteristics of aerosol direct radiative forcing are obvious and its absolute value gradually increases with the decreasing height.The vertical distribution characteristics of the heating rate and the aerosol extinction coefficient are correspondingly consistent.The high value areas are all below 4 km and the daily change is obvious.The maximum heating rate occurs in the 0-1 km,and the maximum value can reach 4.8 K/day.