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中文摘要：
利用离散偶极子近似法（DDA），研究了等效半径尺。在0．8mm范围内的柱状和片状冰晶在不同空间取向、温度和尺度比时，对94GHz雷达发射的水平偏振波产生的后向散射，并讨论了等效雷达反射率因子乙随粒子谱中值直径及冰水含量的变化。结果表明，温度对后向散射效率的影响较低，空间取向对后向散射效率的影响与粒子大小和形状有关。当雷达波垂直指向天顶，在冰晶粒子等效半径Re〈0．8mm时，水平取向冰晶的后向散射效率比随机取向大，粒子越偏离球形，差别基本上越大；在同一取向时，粒子越偏离球形，后向散射效率基本上越大。在一定冰水含量下，取向、形状和冰晶谱的形状参数对五的影响和粒子谱中值直径有关；对于垂直指向的雷达，如果将六角形冰晶等效为等体积球形冰晶，当粒子较大（0．4mm〈Re〈0．8mm）时，其乙将被低估。
英文摘要：
Backscattering characteristics of hexagonal ice crystals with equivalent radius in the range of 0.8 mm with different temperatures, orientations and aspect ratioes at 94 GHz horizontally polarized wave were studied by using discrete dipole approximation （DDA） method, the variations of radar reflectivity factor （Ze） with median diameter （ Dm ） of particles size distribution （PSD） and ice water content （IWC） were also discussed. The result shows that - The temperature impacts slightly on backscattering efficiency （ Qb ） and the sensitivity of Qb to orien- tation depends size and shapes of ice crystals. At vertical radar wave, Qb with horizontal orientation is larger than that with random orientation for equivalent radius Re 〈 0.8 mm of ice crystals, the more departing from spheres for ice crystals morphology, the more difference between them, and the more Qb at the same orientation. At the same IWC, the range of impact of orientation, types of ice crystals and shape parameter of PSD on Ze are related to Dm of PSD. For vertically pointing radar, treating hexagonal ice crystals as equivolume spheres should under- estimate Ze for greater particles （0.4 mm〈 Re 〈0.8 ram）.
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