| The atmosphere contains particles of various shapes and compositions,such as raindrops,hail,snowflakes,ice crystals,and dust.The analysis of particle scattering characteristics is widely used in the field of meteorology.In order to improve the detection and inversion ability of weather radar system,it is necessary to study the scattering characteristics of charged particles,double-layer particles and particle swarm.In this paper,the scattering effect of complex meteorological targets is calculated based on the electromagnetic scattering theory,which mainly includes the following contents:(1)The theoretical calculation methods of scattering characteristics of spherical particles are introduced,including Mie scattering theory,OPAC calculation theory,charged spherical particle scattering theory,double-layer spherical particle scattering theory and DDA scattering theory.(2)According to the scattering characteristics of ice crystal in the atmosphere,the scattering characteristics of ice crystal particles at different number concentration are calculated by OPAC software.The results show that there is a linear relationship between the scattering ability of ice crystal particles and their number concentration.(3)Aiming at the study of scattering characteristics of double-layer spherical particles,the scattering characteristics of different double-layer spherical particles are calculated based on MATLAB.The results show that the scattering ability of melting double-layer spherical particles is much stronger than that of single-layer spherical particles;The backscattering of double sphere is stronger than that of single sphere.(4)Based on the electromagnetic field theory,the scattering formula of charged particles is deduced,and the scattering characteristics of ice ball and water ball particles with different charges and sizes are calculated.The results show that when the particles carry a certain amount of charge,the scattering characteristics will be close to the scattering characteristics of metal particles.(5)Based on DDA and HFSS software,the multiple scattering characteristics of the double sphere system and the double hexagonal prism ice crystal particles are calculated.The results show that the extinction efficiency,scattering efficiency and backscattering efficiency of the double sphere particles reach the peak value when the distance between the center of the sphere is four times of the particle radius.The influence of multiple scattering on the asymmetry factor and single scattering albedo of the double sphere system fluctuates with the increase of the distance from the center of the sphere.The RCS of bihexagonal ice crystal particles considering multiple scattering is larger than that of simple addition;The RCS of bihexagonal prism ice crystal particles increases with the increase of the distance between the centers of the particles.When the distance between the centers of the particles is four times the radius of the outer cylinder of the hexagonal prism,it is the peak value.When the distance exceeds the peak value,the RCS decreases with the increase of the distance between the centers of the particles. |
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