中文摘要：

为了研究大气中冰水两种相态共同存在时粒子的电磁散射特性,本文从Aden-Kerker散射理论出发,分别计算了外包水膜冰球和外包冰膜水球在S波段、C波段和X波段的电磁散射特性,讨论外层覆膜相态和厚度对粒子散射特性的影响;并在MP粒子谱分布和Gamma粒子谱分布的基础上,讨论了融化冰球和冻雨群粒子在S波段、C波段和X波段的衰减、散射、吸收和后向散射特性.结果表明,粒子的衰减截面和后向散射截面并不随外包膜厚度的增大呈现单调变化的趋势,而是与粒子的尺度参数有关,且在不同波段呈现不同的变化特征;融化冰球和过冷却雨的衰减系数、散射系数、吸收系数和后向散射系数与频率和降水强度呈正相关关系,其中MP分布的传播系数要比Gamma分布的传播系数大.此结论对于研究冰水两相粒子对电磁波的散射机制、提高天气雷达探测精度、改善冰水两相粒子的探测效果等具有重要意义.

英文摘要：

To obtain the electromagnetic scattering characteristics of ice-water two-phases particles in atmospheres, the scattering characteristics of water-coated ice spheres and ice-coated water spheres are calculated by Aden-Kerker scattering theory, and the effect of coated phase/thickness on scattering characteristics of particles at S band （wavelength 10 cm）, C band （5 cm）, and X band （3 cm） are discussed. Based on the MP and Gamma drop size distribution （DSD） of precipitation particles, the attenuation, scattering, absorption and back scattering characteristics of wate~coated ice spheres and ice-coated water spheres at S band, C band, and X band are analyzed. The results show that the attenuation cross sections and back scattering cross sections of coated particles varied non- monotonically with the thickness of coated water/ice, which depend on the size parameters of coated particles versus wavelength, and the variation of cross sections of coated particles with the thickness of coated water/ice show different characteristics at different wavebands; in general, when the size parameter is less than 1, the attenuation cross sections and back scattering cross sections of water-coated ice particles are positively correlated with the thickness of coated water, while the attenuation cross sections and back scattering cross sections of ice-coated water particles are negatively correlated with the thickness of coated ice when the size parameters is greater 1, the variation trends of cross sections with coated thickness is much more complex. Considering the drop size distribution, the attenuation coefficients, scattering coefficients, absorption coefficients, and back scattering coefficients of water-coated ice spheres and ice-coated water spheres are positively correlated with the frequency and the precipitation intensity, and the propagation coefficients of MP size distribution are greater than that of Gamma size distribution, which depends on the spectrum characteristics of drop size distribution. These