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 orientation 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 underestimate Ze for greater particles (0.4 mm<0.8 mm).
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