| Aerosols come from a wide range of sources and have important implications for global and regional climate change,air quality,and human health.Aerosol radiative forcing is one of the largest uncertainties in climate change assessments,and the radiative power and effects of aerosols depend on their physicochemical and optical properties.In this paper,the effectiveness of aerosol imaging lidar in supplementing observations of lidar blind areas and the reliability of solar-sky-moon photometric observations are verified by continuous photometric and lidar observations.The inter-month variation characteristics of aerosol optical thickness（AOD）,?ngstr?m wavelength index（AE）,single scattering albedo（SSA）,boundary layer height（PBLH）and vertical profile of aerosol extinction coefficient in Beijing urban area from March2020 to February 2021 are also analyzed.In order to further investigate the influence of the vertical motion of the boundary layer on the particulate matter and its optical properties and the connection between the aerosol vertical distribution characteristics and the meteorological conditions within the boundary layer,the variation characteristics of the meteorological conditions,aerosol optical-radiative properties and gaseous pollutants within the boundary layer during the haze pollution from February8-15,2020 were analyzed with meteorological data.The main conclusions are as follows:（1）Aerosol imaging LIDAR complements the observation of blind areas of LIDAR observation to a certain extent,making the AOD obtained from LIDAR observation more reliable.In spring,the Beijing urban area is mainly affected by a combination of coarse and fine modal particles,while scattered fine particles dominate in other seasons.In summer,the particulate matter（PM）mass concentration is the lowest in the whole year,but influenced by the hygroscopic growth effect of aerosol particles,resulting in the largest AOD in the whole year,the highest aerosol extinction coefficient within 2 km,and the most significant daily variation of the vertical profile of the aerosol extinction coefficient.The boundary layer height develops relatively high in spring and summer（PBLH>1km）.In autumn and winter,the boundary layer development height is relatively low（PBLH<1km）,and the high value area of aerosol extinction coefficient in winter is mainly distributed below 0.5km.（2）During the haze pollution in Beijing from February 8 to 15,2020,the atmospheric diffusion conditions were poor,with weak westerly and easterly winds predominating near the ground,and the convective effective potential energy was negative,which inhibited the occurrence and development of convection and limited the diffusion of pollutants,and the aerosol particles were mainly scattered spherical fine particles,and the aerosol volume spectrum distribution was dominated by bimodal distribution.In this pollution process,the gas pollutants are mainly HCHO and NO2,and the trend of HCHO is similar to the trend of vertical distribution of aerosol extinction coefficient.NO2 has an obvious accumulation process in the early stage of pollution,but its concentration gradually decreases near the ground in the most serious pollution 12-13days.From 18:00 on February 10 to 18:00 on February 11,the extinction of particulate matter caused the solar radiation reaching the surface to decrease,generating an inversion layer and promoting the enhancement of relative humidity,which in turn inhibited the occurrence and development of turbulence,resulting in a lower boundary layer height and the presence of significant sinking airflow,which inhibited the diffusion of pollutants and eventually led to an explosive increase of particulate matter. |
