Multiwavelength Mie Scattering Lidar Aerosol Detection Technology Research

The atmospheric aerosol including dusts,smokes and cirrus cloud is mainly distributed in the troposphere,which affects the radiation balance,chemical processes and earth's climate.Therefore the study of atmospheric boundary layer is though of very importance for improvement of local weather forecast accuracy,prevention and treatment of air pollution,especially for urban meteorological change.This thesis mainly focuses on the fine detection of the atmospheric aerosol profiles in the troposphere.Detecting principle of the Mie scattering lidar for atmospheric aerosol is discussed,a set of multiple wavelength Mie scattering lidar system for aerosol detecting is proposed,Characteristics of Xi'an urban aerosol spatial variations are also observed and analyzed with Mie scattering lidar.In order to eliminate the strong solar background during daytime and to obtain the fine-separation and high-efficiency extraction of Mie scattering signals under different band,improve signal-to-noise ratio,the spectroscopic system is proposed based on a separation film and spectral interference filter,realized the high inhibition rate of other channels.the simulation analysis by the American standard model shows that the lidar system and the detection methods can suppress system noise effectively.And the accurate Profiling of the atmospheric aerosol during daytime can be achieved,when the signal-to-noise ratio in 10,the day system detection height can be obtained up to 11 km.For the needs of urban aerosol profiling in Xi'an and variations,the research of the aerosol observation experiment by Mie lidar and corresponding data procession of aerosol optical properties has been developed.The atmospheric aerosol profile height distribution,the optical thickness distribution profile with different wavelength,the Angstrom index and other parameters are achieved.The experimental results show that the design of multiple wavelength Mie scattering lidar system can realize the concentration distribution of different size of atmospheric aerosol particle approximately.Finally,on the basis of analyzing of the inversion algorithm of aerosol extinction coefficient,to the requirements of the study of nonspherical aerosol spectral distribution,the improvement scheme of system is discussed,which will provide theoretical basis for further research.