Experimental Study On Spatial And Temporal Distribution Of Atmospheric SO₂ And NO₂ Concentrations In Huainan By Differential Absorption Lidar

Sulfur dioxide(SO2)and Nitrogen dioxide(NO2)are common pollutant gases,which are harmful to the natural environment and animals and plants.It is especially important to measure the concentrations of these two pollutant gases by using reason-able and effective monitoring methods.As one of the many technical means to detect the concentrations of SO2 and N02,differential absorption lidar has outstanding advantages in detecting atmospheric SO2 and NO2 concentrations because it can con-tinuously,instantaneously and rapidly monitor atmospheric pollutants,and its detection results have high spatial and temporal resolution.This paper discusses the basic physical and chemical properties of SO2 and NO2 and their monitoring techniques,and describes the basic principle of differential absorp-tion lidar for measuring gas concentrations.The system structure of SO2/NO2 differ-ential absorption lidar developed by Anhui Institute of Optics and Fine Mechanics of Chinese Academy of Sciences is introduced.Write programs to invert the concentration data of SO2 and NO2 in the atmosphere measured by SO2/NO2 differential absorp-tion lidar.Through the inversion,the gas concentration distribution profiles of SO2 and NO2 on the horizontal and vertical detection paths can be obtained.The concentrations of SO2 and NO2 obtained by the inversion are comparable with the concentrations of SO2 and NO2 reported by local environmental monitoring stations,and the errors of the SO2 and NO2 gas concentrations measured by SO2/NO2 differential absorption lidar are also analyzed.According to the atmospheric SO2 and NO2 concentration data in the part of the period from July 2016 to June 2017 measured by SO2/NO2 differential absorption lidar in Huainan Academy of Atmospheric Sciences,the gas concentration distribution profiles can be obtained by inverting these concentration data,in this paper,the typical examples of gas concentration profiles are selected to analyze the distribu-tion characteristics of SO2 and NO2 from three aspects:horizontal concentration changes in the afternoon and night,vertical concentration changes and monthly varia-tions of horizontal concentration.The results show:(1)The concentrations of S02 and N02 at night are greater than that of SO2 and NO2 in the afternoon on the same day;(2)The vertical concentrations of SO2 and NO2 decrease with the increasing height;(3)The monthly variations of SO2 and NO2 horizontal concentration are the highest in the winter months,and the lowest in the summer months,followed by the spring and au-tumn months.The changes in SO2 and NO2 concentrations are due to the combination of population activities and changes in meteorological conditions.