Study On The Scalar And Vector Radiation Transmission Characteristics Of Laser In Plane Parallel And Spherical Boundary Clouds

The problem of laser radiation transmission in clouds is an important part of the study of laser propagation and scattering characteristics in random media.As a common discrete random medium in the atmosphere,cloud will inevitably cause interference to satellite ground laser communication,atmospheric remote sensing and target detection.Therefore,it is of great significance to study the radiation transmission characteristics of laser in cloud for satellite ground laser communication,atmospheric remote sensing and target detection.In this thesis,based on the theory of atmospheric radiation transmission,the scalar and vector radiation transmission characteristics of laser in plane parallel and spherical boundary water cloud and ice cloud atmosphere are studied respectively.The main work includes:1.Some basic concepts of cloud scattering radiation are introduced.Combined with the microphysical parameters of spherical droplets and nonspherical ice particles,the average scattering characteristics of water cloud and ice cloud are given.The scattering phase matrix of water and ice clouds with certain distribution characteristics is studied.2.Based on the scalar radiation transfer equation of the plane parallel atmosphere,the discrete vertical scale method is used to numerically calculate the reflectivity and transmittance of the homogeneity water cloud and ice cloud atmosphere with the water cloud and ice cloud atmospheric parameters such as:optical thickness,effective radius,Observation angle and other changes were analyzed,and the influence of the overlapping cloud model of vertical inhomogeneity water cloud and ice cloud covering the water cloud on the laser radiation transmission characteristics is analyzed.3.Based on the Monte Carlo model of vector radiation transmission,the plane-parallel atmosphere is first extended to a spherical atmosphere,and the difference in the reflectivity of the water cloud and ice cloud atmosphere under the two boundary atmosphere modes(plane parallel and spherical boundary)is studied.Secondly,when considering the incidence of a large zenith angle in a spherical boundary atmosphere,the polarization radiation transmission characteristics of three laser wavelengths(0.65μm,0.85μm,1.55μm)are numerically calculated,which vary with the optical thickness,effective radius,liquid/ice water content,surface albedo and relative azimuth of water and ice clouds.The results show that the reflectance of water cloud and ice cloud increases with the increase of optical thickness,the transmittance decreases with the increase of effective radius,and the reflectance and transmittance of ice cloud and water cloud are related to the scattering phase function with the change of observation angle.In addition,for the vertical inhomogeneity In the model of water cloud and overlapping cloud,the inhomogeneity of water cloud and overlapping cloud have great influence on the radiative transfer of water cloud and ice cloud.Under parallel plane and spherical boundary atmosphere,the differences of atmospheric reflectivity of water cloud and ice cloud gradually increases with the increase of zenith angle.In the vector radiation transmission based on the spherical boundary atmosphere,with the increase of optical thickness and liquid/ice water content,the reflectance of water cloud and ice cloud increases,and the degree of polarization decreases,while with the increase of effective radius and surface albedo,the reflectance of water cloud and ice cloud decreases,and the degree of polarization increases;In addition,the effects of different ice particle models on the reflectance and the degree of polarization of the ice cloud are greater.