Detection Method And Simulation Analysis Of Air Temperature Based On High Spectral Lidar

Near-surface and surface temperature of air are important meteorological parameter.The generation,disappearance and real-time variation of various weather phenomena are closely related to the air temperature.The air temperature directly affects every aspect including human activities and agricultural production.As an active remote sensing detection tool,lidar can detect air temperature with high temporal and spatial resolution.Based on the dependence of Rayleigh scattering spectral width on temperature,high spectral resolution lidar for atmospheric temperature detection has been widely used.This thesis mainly focuses on the problem that the air temperature detection means can not avoid the radiation from the sun and the ground.Based on the physical concept of temperature,an air temperature detection system based on high spectral lidar is proposed and designed.The detection system was analyzed by the study of scanning object(Rayleigh-Brillouin scattering spectrum modeling),scanning device(key parameters design of scanning spectroscopic system),scanning process and results(theoretical calculation and Zemax optical scanning simulation).Firstly,the scattering of molecules in air is modeled mathematically,and we obtained the spectrum forms of Rayleigh-Brillouin scattering at different temperatures and pressures.We focus on the effect of S6 and G3 scattering models on the separation of Rayleigh component and Brillouin component.Aiming at the accuracy requirement of air temperature retrieval,the Rayleigh component separated from the G3 model is specially optimized.Four coefficients of the G3 model are optimized to make the error of Rayleigh component to spectrum less than 0.03%at y=0,346.With the increase of y value,the error also increases.At y=1.481,the error is still less than 0.30%,which meets the accuracy requirement of temperature retrieval.Then,this thesis completes the parameters design of confocal cavity spherical Fabry-Perot interferometer as the core component of the scanning spectroscopic system.And this thesis analyses the influence of the interferometer parameters on temperature retrieval.By comparing the theoretical calculation results with the simulation results of the spectral line of the transmittance function of the confocal cavity spherical Fabry-Perot interferometer with Zemax optical software,the influence of incident angle on the spectral line of the transmittance of the interferometer is analyzed,the angle of incidence should be kept between 0 and 1.07°.The detection system is analyzed theoretically,and the influence of pressure,wind speed and Mie scattering are evaluated.The process of interferometer scanning the Rayleigh-Brillouin scattering spectrum of the real atmosphere was simulated by Zemax software.The scanning results are compared with the theoretical calculation,and the influence of convolution process on the detection results is analyzed.Aiming at the influence,a deconvolution calculation method is proposed and reduces the influence of interferometer on the detection results during the convolution process.The air temperature T was successfully retrieved by putting the scanning results into the G3 model formula to calculate y value,inversion temperature error is within±1.25K.