| In modern society,the electromagnetic wave and our daily life are inseparable.Light is one of the electromagnetic wave,which has been widely used in various aspects such as target detection,information transmission and remote imaging etc.;In these areas,light propagates in atmosphere and affected by atmospheric scattering.But the haze makes the atmosphere composition and air quality change significantly,which has a great influence on the engineering field,so the research on light scattering characteristics of the atmospheric haze is important significance.In this paper,firstly,the scattering intensity,polarization and efficiency factors of haze particles are calculated by the Discrete Dipole Approximate(DDA),ranging from simple shape to complex shape based on Cluster-Cluster Aggregation(CCA)theory.Secondly,the variation trend of the optical transmittance of haze with the propagation distance is calculated by the Monte Carlo Method,whose size parameter follows a certain distribution.The main content of this paper can be divided into the following aspects;Above all,the scattering characteristics of simple haze particles are preliminarily calculated by the discrete dipole approximate,in specifics which can be divided into the following ways.First of all,the results calculated by discrete dipole approximate are verified by comparison with the results of the analytical solution of Mie theory,and ensuring the accuracy of the calculation of the haze by DDA.Secondly,the scattering characteristics of simple haze particle are calculated.The effects of spherical radius and complex refractive index of haze on the scattering intensity and polarization are calculated.The effects of haze particle wrapped by water and without wrapped by water on the scattering intensity,efficiency factors and polarization are studied.Keeping the particle radius unchanged,the effects of the axial ratio of ellipsoidal particle on scattering intensity,the efficiency factors and polarization are studied.The effects of the aspect ratio of cylindrical particles on scattering intensity,the efficiency factors and polarization are studied.Finally,the scattering characteristics of the composite particles are calculated.When the radius is constant,the scattering intensity,polarization of the composite particles are calculated andcompared with the results of sphere,ellipsoid and cylinder particles.Scattering intensity,the efficiency factor and the polarization of the multi-component haze particle wrapped by water and without wrapped by water are calculated.Second,the complex cluster models of haze are built by CCA theory and the scattering characteristics of the cluster particles are calculated by using the DDA method.Keeping the particle radius and the number of monomers unchanged,the influence of the different structures on the scattering field intensity is calculated.In a certain radius,the effect of the number of monomers on the intensity of scattering field is calculated.The scattering field intensity and polarization of ammonium sulfate,carbon sol and ammonium nitrate cluster particles are respectively calculated and compared with the results of the equal radius' s sphere.All of the haze components are mixed according to a certain proportion,there are three kinds of mixed approaches,which are respectively mixed cluster consisting of homogeneous monomers,the mixed cluster consisting of inhomogeneous monomers and the equivalent sphere whose mixed ratio of haze is equal to clusters'.The variation of these haze model of scattering intensity and polarization with the scattering angle are calculated and these models' results are compared with each other.The haze cluster particles' variation of the scattering field intensity and polarization with the scattering angle and the efficiency factor with the size factor were analyzed,which contain ammonium sulfate,carbon sol and ammonium nitrate and orientation change randomly.The haze cluster's components are mixed according to a certain proportion with random direction.The variation of these cluster models of scattering intensity and polarization with the scattering angle are calculated and these models' results are compared with each other.The haze cluster particles are wrapped by water with random direction,of which the variation trends of the scattering field intensity,the polarization with the scattering angle and efficiency factors with the size parameter are calculated.Third,based on the scattering characteristics of haze particles,the light transmittance of a certain distribution of fog and haze medium is calculated by using the Monte Carlo Method referred to as MC.Mainly including the following two aspects:First of all,the extinction coefficient and the transmittance of soot and water sol are calculated,and find that the results are consistent with the literature's,thus the calculation to haze transmittance has a reliable guarantee.Secondly,the transmittance of the fog and haze is calculated.The variation trend of water particle of the transmittance with the transmission distance is calculated,which follows modified exponential distribution.The variation of the fog of the transmittance with the transmission distance is calculated,the fog particle radiuses follow the ocean distribution and the continental distribution.The variation trend of the light transmittance with the transmission distance of haze particles is calculated,whose size parameter follows the normal distribution.Then,water particles whose size parameter follows the exponential distribution are externally mixed with haze particles,of which the variation trend of the light transmittance with the transmission distance is calculated,and compared with that of haze.The variation trend of light transmittance with the transmission distance of particles is calculated,which are wrapped by water and follow the normal distribution.The variation trend of clusters of light transmittance with the transmission distance is calculated,which are wrapped by water and follow the normal distribution. |
PDF Full Text Request