Research On Polarization Characteristics Of Sky Based On Vector Radiative Transfer

The sunlight is natural light,and the light is an electromagnetic wave.During thetransmission process,electromagnetic waves are scattered and absorbed by atmospheric molecules,aerosol particles,clouds,etc.,and absorbed and reflected by the underlying surface,resulting in polarization characteristics.Polarization is one of the important characteristics of light.The study of polarization characteristics of the sky is of great significance in many fields such as polarization navigation and atmospheric remote sensing.It has become a hot research topic at home and abroad.In order to study the influence of various factors on the polarization characteristics of the sky and analyze the polarization characteristics of the sky under actual atmospheric conditions,this paper established the sky polarization model based on vector radiation transmission,simulated and analyzed the influence of various factors on the polarization characteristics of the sky,and tested and analyzed the polarization characteristics of the sky under actual atmospheric conditions.These provide theoretical support and experimental data for the practical application of sky polarization characteristics.Firstly,based on the theory of atmospheric radiation transmission,this paper expounded the scattering theory of atmospheric medium on radiation transmission,analyzed the causes of sky polarization characteristics,and focused on the transmission equation of atmospheric vector radiation.The Monte Carlo principle is used to solve equations by numerical simulation.At the same time,according to the atmospheric model,aerosol model,cloud parameters,etc.,the sky polarization modeling method based on the vector radiation transfer equation is introduced.Secondly,this paper uses the sky polarization model based on vector radiation transfer equation to simulate and analyze the effects of atmospheric mode,surface albedo,aerosol model and water cloud on the polarization characteristics of the sky.The results show that the atmospheric mode has no effect on the polarization characteristics;the change of surface albedo has no effect on the angle of polarization,and the degree of polarization decreases with the increase of surface albedo;the degree of polarization decreases with the increase of the concentration of components in different aerosol models,and decreases with the increase of aerosol optical thickness,but the aerosol has no effect on the angle of polarization;as the aerosol optical thickness increases,the aerosol has little effect on the polarization azimuth;the water cloud greatly affects the distribution of polarization characteristics,and the water cloud destroys the angle of polarization distribution.It also attenuates the value of the degree ofpolarization,and as the optical thickness of the water cloud increases,the degree of polarization decreases rapidly.Finally,this paper used image-based sky polarization characteristic test system to carry out several test experiments.Through the data processing analysis,the influence law of aerosol and cloud on the polarization characteristics of the sky is studied.The results show that the degree of polarization is distributed in the ring around the sun,increasing first and then decreasing along the solar meridian;the angle of polarization distribution is stable,±90degrees on the solar meridian,which is consistent with the simulation results.The degree of polarization decreases as the concentration of PM10 and PM2.5 increases,and the cloud layer also weakens the degree of polarization and destroys its annular distribution.The angle of polarization is largely unaffected by aerosols and a small amount of cloud,but the angle of polarization near the sun causes the numerical limits to be unclear due to overexposure.