This paper is devoted to the calculation of ice content-dependent,refractive index of mixed ice–water particles in clouds and precipitation from Debye's,Maxwell Garnet's and other models and the e4ects of di4erently structured particles upon microwave absorption,scattering and backscattering cross-sections.Evidence suggests that while both the real and imaginary parts of the refractive index diminish with increased ice content of such a sphere,the radiation intensity variation di4ers from one model to another.The results from the commonly used Debye's algorithm go to an extreme.Mie's theoretical calculations show that for a 7xed sized mixture its absorption cross-section may exceed that of a pure water particle of the same size.At a small physical parameter |2πmr=/λ|,the scattering cross-section decreases with increased ice content f,and at a bigger value of the parameter,the cross-section may be greater at a certain f range than that of a pure water sphere of the same volume.The absorption,scattering and backscattering cross-sections of a mixture change with f in an oscillatory manner.However,di4ering algorithms of the refractive index give di4erent oscillation's features.Since these algorithms are based on particular assumptions of the physical properties of these mixtures,our conclusions achieved here can be utilized as a reference in the study of microwave transfer and atmospheric remote sensing.

Twenty sphere-cone-oblate ice particles are simulated for their backscattering observations in a microwave lab and calculations are done with the DDA method.The lab experiment and the DDA theory are brie7ypresented in this paper.The theoretical results are compared with the lab observations.It is shown that the theoretical results are consistent with the experimental data in general and that the backscattering ability of sphere-cone-oblate ice particles increases as the particle size parameter increases,and 7uctuates in the so-called resonance region.The backscattering cross sections of sphere-cone-oblate ice particles depend not only on their sizes equivolume spherical radii Re but also on their shapes.There is a statistically linear relationship between di:erential re7ectivity ZDR and the shape factor, 2a/h,which is the ratio of the horizontal scale to the vertical scale of a particle.

This paper experimentally and theoretically examines the scattering properties of simulated non-spherical hydrometeors including water oblates, ice oblates and ice sphere-cone-oblates,in terms of the backscattering cross-section and the differential reflectivity.The experimental measurements of the backscattering cross-sections of non-spherical hydrometeor samples were performed in the Electromagnetic Scattering Laboratory of China National Space Industrial Corporation.Meanwhile,the backscattering cross-sections have been computed with the transition(T) matrix method.The theoretical results are compared with the experimental data,showing that the calculations are consistent with the observations in general.Experimental and theoretical analyses indicate that the backscattering cross-section of non-spherical particles increases as the particle size parameter increases,and fluctuates when the sizes are larger under the effect of resonance scattering.Differential reflectivity ZDR of water oblates in natural rainfall is always greater than 0dB whereas ZDR of hailstones may be negative.There is a good linear relationship between differential reflectivity and aspect ratio of a particle.These derivations agree with the literature and can be used to identify the presence of hail particles and distinguish between plate-type and columnar-type hydrometeors.In this study,the measuring experiment and the T-matrix method calculations for the scattering of simulated raindrop and ice particles are also briefly described.