Inversion And Analysis Of Aerosol Optical Properties In Nanjing By Ground-based Sun-photometer

Aerosol optical properties have great influences on atmospheric energy,environment and climate change.Aerosol optical depth,Angstrom exponent,single scatter albedo,scatter phase function and polarized phase function are used to describe aerosol optical properties.To make quantitative remote sensing more accurate,it is necessary to retrieve these aerosol optical properties.Firstly,the newest observation data of CE318 in Nanjing are used to retrieve AOD and Angstrom exponent between December 2017 and November 2018.Then statistical analysis of annual data is made which deepen the understanding of aerosol characteristics in Nanjing and provide reference for the study of aerosols in the Yangtze River Delta.The retrieval results indicate that: the annual average value of AOD in Nanjing is 0.541±0.325.Compared with other regions in China,it can be seen that the pollution in Nanjing has been alleviated and the environment is getting better and better;The daily variation feature of AOD is that AOD in the afternoon is higher than that in the morning and the daytime value is relatively stable.The Angstrom exponent is higher than 1.0 throughout the day,indicating that the main control aerosol in Nanjing are fine particles;The frequency distributions of AOD and Angstrom exponent in the whole year agree with log-normal distribution,the aerosol master mode is relatively stable,which means aerosol of Nanjing belonging to the urban-industrial aerosol type.Then,multi-band scattering phase function,polarized phase function and single scattering albedo based on observation data of Changxing area is retrieved to verify the correctness of the inversion of phase function based on SOS algorithm.After that,four seasons and annual average scattering phase function in Nanjing between December 2017 and November 2018 are retrieved.Lastly deeply analysis of the influence of surface albedo,refractive index and Angstrom exponent on the phase function has been made,which Deepens the understanding of the character of the phase function and lays the foundation for the follow-up further research.The results show that: The annual average scattering phase function in Nanjing is closer to the urban aerosol scattering phase function than continent.The scattering phase function in spring affected by dust particles has strong forward scatter and weaker back scatter;As the polarization characteristic parameter of aerosol,polarized phase function is very sensitive to the absorption properties of aerosol particles;the polarization phase function changes synchronously with the Angstrom exponent,which means the polarized phase function can be used to characterize the size of aerosol particles.