Study On The Vertical Distribution Characteristics Of Aerosol Over Typical Areas Of The Yangtze River Delta Based On Lidar

Since the reform and opening up,with the acceleration of urbanization and the rapid development of economy,environmental problems are exerting a tremendous concern on us.Although the proportion of aerosol is very low in atmosphere,it plays a very important role in human production and life.Laser radar is the product of the 1960s.By virtue of high resolution,strong direction and continuous observation,many scholars have used it to study the characteristics of the vertical distribution of aerosols,which is of great significance for the study of the effect of aerosol radiation and the study of global climate change.In this paper,with the use of micro pulse laser radar data and the CALIPSO satellite borne lidar data,three typical cities of the Yangtze River Delta(Shanghai,Nanjing and Suqian)are selected for studying and analyzing the characteristics of the vertical distribution of the aerosol.First,using CALIPSO and micropulse lidar data,the extinction characteristics of clean and polluted days in Nanjing are compared.Then,based on CALIPSO lidar data,the vertical distribution characteristics and pollution types of aerosol in four kinds of weather(clean,haze,dust,fireworks and firecrackers)in Suqian area are analyzed.In the last,the haze pollution process of Shanghai area on December 2016 4-10 day was analyzed.Combined with the ground meteorological elements,particle concentration and sounding data,the relationship between the meteorological elements near the ground and high altitude,the height of the boundary layer,the aerosol extinction coefficient and the concentration of particles in the pollution process was analyzed,and the cause of the pollution weather process was found.The main conclusions are as follows:(1)Whether it is clean day or pollution day,there is a slight difference between the peak value of the extinction coefficient and the corresponding height in two kinds of weather observed by two laser radar in Nanjing,but the overall variation trend of the extinction coefficient profile is similar;Comparing the inversion results of CALIPSO lidar and the results detected by the micro pulse lidar,these two show a great consistency.(2)The difference of aerosol extinction coefficient,color ratio and depolarization ratio under different weather in Suqian is great,and the vertical distribution of different types of polluted weather types is closely related to the height distribution of the pollution sources.A kind of weather type pollution is often composed of different aerosol types.Aerosol optical parameters vary a lot at different heights,and the sources of pollution vary too.(3)The peak of daytime extinction coefficient in the process of pollution in Shanghai mostly appears at the height of 500-1500m,and there are also several peaks of extinction coefficient peak at 5 and 7 days.It shows that the pollution process is not only from local pollution,it may be caused by the transportation of pollutants in the region,and the static weather caused by the stronger inversion layer and low air atmosphere make great accumulation of material in the near ground,which is the main cause of the pollution.From the transmission of the polluted region,the transportation of the Yangtze River Delta and its surrounding area and the local emission of Shanghai are the main causes of the pollution process.