| The effect of atmospheric aerosols on sunlight will seriously affect the Earth's atmospheric environment.Lateral lidars have obvious advantages in atmospheric aerosol experimental detection.With the development of computers,the Monte Carlo method is continuously used in the simulation analysis of laser atmospheric detection,and has greater advantages than traditional analysis,so the advantages of both are combined with atmospheric aerosols.Experiment and simulation analysis have great significance.In this paper,a Side-scattering lidar system based on electric coupling device(CCD)(Clidar system)is built.The atmospheric scattering coefficient curve is experimentally inverted,and Monte Carlo simulation and analysis are carried out on the system.The specific research is as follows:(1)The significance of studying atmospheric aerosol is introduced.The advantages of lidar and Monte Carlo in aerosol research are expounded.A detailed introduction to Monte Carlo's research status at home and abroad in laser detection.(2)The theoretical basis of laser transmission in the atmosphere is introduced,including the composition of the atmosphere,the propagation characteristics of the Gaussian beam in the medium and the main physical parameters,the transmission characteristics of the laser in the atmosphere,and the three scatterings of the laser and the atmosphere.The theoretical basis of the single spherical particle to the Mie scattering of laser;the introduction of Monte Carlo theory,including the idea and application of Monte Carlo,introduces several Monte Carlo application methods,and introduces the phase functions used in several simulations.And the advantages and disadvantages of the Monte Carlo method.(3)According to the rice scattering theory and the laser transmission equation,a method for inverting the scattering coefficient curve based on Clidar's lateral scattering echo signal graph is obtained.A Clidar experimental device with a laser with a wavelength of 532 nm as a light source and a CCD as a receiver was built.The spatial distribution curve and scattering coefficient curve of light intensity in three days with different visibility are described.According to the experimental results,when the visibility increases,the light intensity decreases,the spatial distribution of the light intensity is more uniform,and the slope of the light intensity cur\^e decreases.The scattering coefficient curve decreases with the increase of visibility,and the scattering angle of the large angle is less.It is deduced and found that there is a certain linear relationship between extinction coefficient and total light intensity,so a way to measure visibility is proposed.After comparison with the experiment,the error of the experimental results is within the acceptable range,indicating the feasibility of this method.(4)A lateral scattering theory model based on Monte Carlo method is established for the Clidar system.The lateral scattering mechanism of atmospheric aerosol to the lidar beam is studied under multiple scattering conditions.The simulations and experimental curves are compared to verify the feasibility of the Monte Carlo method to simulate the scattering mechanism of side-scattering lidar.The model is used to compare the scattering coefficient curves obtained by simulation and experiment under different visibility conditions.The correlation between simulation and experiment is over 95%,and the two have strong consistency.The average scattering factor ?s and the asymmetry factor g are studied.During the simulation,g is taken as 0.1,0.3,0.5,0.7,0.9 and simulated by the scattering coefficient curve.It is found that g affects the degree of tailing of the scattering curve.Fix g to let ?s value from 0.35 to 0.8 in steps of 0.05.The simulation results show that Pshas a linear relationship with the total photon energy on the photon detector.The simulation overall illustrates the close relationship between the key parameters in the model and the atmospheric conditions. |
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