The Precise Retrieval Of Aerosol Optical And Microphysical Properties From Combined Lidar And Sun Photometer Observations

Aerosols play an important role in the study of atmospheric radiation and climate change.Aerosol optical and microphysical properties is useful for analyzing the effects of aerosols on environmental climate,smog mechanisms,and et al.Multi-wavelength lidars and sun photometers are effective instruments for studying aerosol optical and microphysical parameters.Their combination can complete each other and study the optical and microphysical properties of atmospheric aerosols.The paper mainly focuses on two parts.The first part is the study of microphysical parameter inversion algorithm from sun photometer data.The regularization method based on minimum discrepancy principle and using the prior value is built on to retrieve aerosol size distribution.By analyzing the error data of different models,a method for averaging that can achieve stable outputs is proposed.The reliability of the algorithm is verified and tested by the measured aerosol size distribution.The algorithm can obtain aerosol size distribution with radius from 0.1?m to 100?m.The maximum inversion error of microphysical parameters is less than 32%.The errors of lidar ratio can be controlled within 34%.The algorithm is classified and verified by more model data.The results show that the algorithm is reliable.According to the inversion algorithm,the sun photometer data in Xi'an area is calculated in the past three years.The changes of lidar ratio and particle size distribution at the sunny day and haze day are studied.The seasonal variations of the lidar ratio from 2015 to 2017 are analyzed.The second part mainly studies the retrieval of aerosol optical and microphysical properties from lidar and sun photometer measurements.The boundary value selection method which is used to retrieve optical parameters from Mie lidar data is studied by combining the sun photometer data.The optical profiles at 355nm,532nm and 1064nm are retrieved by using the Fernald method.The results are compared with the retrievals from Raman signal,and the errors can be controlled within 20%.The inversion data combined lidar and sun photometers is analyzed.The results show that 44%-72%of total atmospheric column extinctions are contributed by aerosol particles within 1.2km-6.2km.The optical and microphysical parameters in vertical height are calculated and analyzed.The effective radius of the aerosol particles in each layer is compared with the mean effective radius of the entire atmospheric column based on the sun photometer.The column size distribution is preliminarily compared with the size distribution in each height.