Research On Inversion Of Aerosol Microphysical Parameters Based On Linear Estimation Method

Atmospheric aerosols affect climate and environmental changes,and studying the vertical distribution of aerosol microphysical properties is of great significance for studying the causes of climate change and environmental pollution.Multi-wavelength lidar systems are effective instruments for detecting the vertical distribution of aerosols.The paper mainly focuses on the method of retrieving aerosol microphysical parameters based on lidar remote sensing data.The main work is as follows:Perform parametric analysis and research on the aerosol particle spectrum collected by in-situ measurement equipment.Using the Gamma distribution model to fit the particle spectrum,it is found that there is a very good linear relationship between the scale parameter λand the shape parameter μ in the Gamma parameter,and the parameterized equation between them is given to invert aerosol particles spectrum research analysis provides support.The data inversion algorithm of aerosol microphysical parameters-linear estimation algorithm,and its inversion ability and calculation accuracy of microphysical parameters obtained by laser radar optical parameters are studied.For aerosol microphysical parameters(number concentration,volume concentration,Surface area concentration,effective radius)were numerically simulated and verified.Substituting the spectral distribution models of three aerosol types(urban industrial,desert dust and oceanic,biomass burning)into the linear estimation algorithm,the inversion error of microphysical parameters within 25%.At the same time,the noise resistance of the algorithm was evaluated.When the error within ± 10%was added to the optical parameters,the inversion error of the microphysical parameters increased with the increase of the error of the optical parameters,and increased to 35%.When an error of 25%is introduced into the optical parameters at the same time,the relative error of the parameters varies within the range of 40%.Based on the microphysical parameters obtained by the linear estimation algorithm,combined with the Gamma spectral distribution model and parametric equations,the inversion of the aerosol particle spectrum was realized,and the inversion error of the particle spectrum was within 45%.The inversion and analysis of optical parameters and microphysical parameters are performed on the lidar remote sensing detection data.The backscattering coefficient(β)and extinction coefficient(α)of atmospheric aerosols were calculated using the Fernald method and the Raman method,respectively,and the different types of weather(sunny day and foggy days)for inversion of microphysical parameters.The experimental results show that:under different weather conditions,there are obvious differences in optical parameters and microphysical parameters,and the optical parameters and microphysical parameters in foggy days are larger than those in sunny days,which is consistent with the weather conditions at that time.