Aerosol Vertical Distribution Characteristics Observed By Lidar In Different Climate Zones

Atmospheric aerosol and planetary boundary layer(PBL)are important parts of the vertical structure of atmosphere.As an active remote sensing device,lidar can continuously achieve high temporal and spatial resolution data.Lidar is a powerful tool for studying the temporospatial characteristics of aerosol vertical structure and planetary boundary layer height(PBLH).The PBLH as an important parameter of PBL is affected by the local underlying surface and meteorological elements.The PBLH is closely associated with human's activities.The method to retrieve the PBLH by lidar data is to utilize the aerosol as the tracer.In order to improve the inversion results of PBLH by lidar,a 2-D matrix method is proposed.The four lidar observation sites'data of Jinhua,Hefei,Lanzhou and Beijing is used in our analysis.PBLH is retrieved by these data to explore the temporal and spatial variation of PBLH over these sites.At the same time,optical properties of aerosols are retrieved from lidar data observed over Jinhua and Hefei to explore the temporal and spatial variation of aerosol vertical distribution.The mean PBLH in Lanzhou is higher than other three sites in spring,summer and autumn.Not long after sunrise,the PBLH increased significantly over Lanzhou,but the PBLH at Hefei dose not rise significantly until a few hours after the sunrise.The maximum month mean diurnal PBLH in Jinhua,Hefei,Lanzhou and Beijing appears in September,August,June,and August,respectively.Hefei has the longest time from sunrise to when it reached the maximum PBLH,followed by Jinhua and Beijing,and Lanzhou has the shortest time.The diurnal PBLH at Jinhua observation site has a good correlation with the surface temperature.The aerosol vertical distribution and its optical properties are retrieved and analyzed by the lidar data over Jinhua.The profiles used to analysis are cloudless or cloud base height above 6 km.It is found that Jinhua aerosol has a vertical distribution with a multi-layer structure.Aerosol optical properties have seasonal characteristics and variated with height.In autumn,winter and spring,the occurence frequency of the aerosol layer at 3-6 km is higher than that in summer,especially in spring.In autumn,winter and spring,the average depolarization ratio of aerosol particles at 4-6 km exceeds 0.1,while in summer it is less than 0.05.In autumn,aerosols with a larger color ratio appear at 0-2 km.According to the analysis of the backward trajectory,it is found that Jinhua is affected by transported dust aerosol at 4-6 km in autumn,winter and spring,and influenced by transported ocean aerosol at 0-2 km in autumn.Two cases on December 22 and 31,2013 show that aerosols below 2 km are mainly affected by local sources,while aerosols at 2-6 km are influenced by transmission air parcel.The aerosol optical properties were retrieved by the lidar data over Hefei,and statistics and analysis results were carried out as well.It is found that the aerosol optical properties below and above PBLH over Hefei show difference,especially the color ratio.According to the temporospatial of PBLH and aerosol distribution(Jinhua,Hefei)observed at the four observation sites in Jinhua,Hefei,Lanzhou,and Beijing,it is found that there are present differences between diurnal and seasonal variations of PBLH.The PBLH is higher in summer,but lower in winter.The PBLH is higher in high latitudes,while lower in low latitudes.The PBLH is higher in arid areas,but lower in humid areas.The PBLH is higher in warm temperate areas,and lower in subtropical regions.That difference may due to the surface types and meteorological elements.The vertical distribution of multi-layer aerosols over Jinhua is affected by dust sources,ocean sources,and local source aerosols.Our research has great significance for investigating the temporal and spatial characteristics of the PBLH and aerosol vertical distribution with difference region.