Light Scattering Properties Of Agglomerated Nucleated Shell-structured Ice Crystall Particles

Laser scattering of ice particles has important research value for wireless optical communication,meteorology and military.Due to the complexity of the composition of atmospheric aerosol particles in nature,the diversity of crystal core media in the heterogeneous nucleation process of ice crystal particles leads to the attenuation of laser light intensity in the wireless laser communication link of these core-shell structure ice crystal particles.Therefore,it is of great value to study the scattering characteristics of ice crystal particles by discussing their laser attenuation characteristics of ice crystal particles with complex structures.Starting from the internal generation mechanism of heterogeneous nucleation of ice crystal particles,this thesis studies the influence of the scattering characteristics of ice crystal particles with complex structure on laser propagation.The main research contents are as follows:1.Using the method of discrete dipole approximation,the mechanism of heterogeneous nucleation of ice crystals in the tropospheric aerosol particles,such as soot coal,dust,soluble and oceanic aerosol particles,was analyzed,ideal spherical core-shell structure of ice crystal particles scattering characteristics,numerical simulation of the different incident light wavelength,the size of the crystal nucleus and four kinds of aerosol particles with different mixing ratio,sphere,ellipsoid ideal core-shell structure of ice crystal particles extinction,the change of absorption and scattering coefficient.2.Considering the influence of the intermediate mixed layer structure of the core crystal structure of the core-shell structure on the ice-particle scattering characteristics of the core-shell structure,the formula for calculating the refractive index of the intermediate uniform mixed layer is derived,and the intermediate mixed layer is established.The core-shell ice crystal sub-model of the structure;four special core-shell ice crystal sub-models of sphere,ellipsoid,hexagonal plate and hexagonal prism were established.3.The shapes of atmospheric aerosol particles are mostly irregular and complex structures.In order to study the influence of crystal core shapes on the scattering characteristics of ice crystal particles,spherical,long ellipsoid,flat ellipsoid and other crystal core models were established,and the influence of these crystal core shapes on the scattering characteristics of ice crystal particles in core-shell structure was compared.The numerical results show that compared with the three aerosol particles of dust,soluble and oceanic,the core-shell structure ice crystal particles of soot coal aerosol particles as the core medium show stronger light absorption.Particle phase at the same time,the effective size sphere,ellipsoid,hexagonal flat and hexagonal prisms four kinds of core-shell structure of ice crystal particles,a single hexagonal prisms ideal core-shell structure of ice crystal particles scattering direction,the most obvious and single spherical ideal core-shell structure of ice crystal particles scattering direction of the worst,and the intermediate mixed layer is considered the core-shell structure of ice crystals is greater than the ideal structure of core-shell particles ice crystal particles of light scattering intensity.Among the ice crystal particles with four special agglomerated core-shell structures of sphere,ellipsoid,hexagonal plate and hexagonal prism,under the same size,the forward scattering intensity of ice crystal particles with agglomerated core-shell structure of hexagonal prism has the largest,and the scattering direction is significant,and the distribution of scattering intensity with scattering Angle has the most complex.The above results show that the shape of particles,complex core-shell structure and the diversity of crystal core medium have significant influence on the scattering characteristics of ice crystal particles.In addition,particle shape,particle spatial distribution and the density of ice crystal particle model have great influence on the scattering intensity of ice crystal particles.