Millimeter wave scattering from spatial and planar bullet rosettes
Millimeter wave scattering from spatial and planar bullet rosettes
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空间和平面子弹玫瑰花结的毫米波散射
DOI：
10.1109/36.752232
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
T. Walsh
中科院分区：
文献类型：
--
作者：
K. Aydin;T. Walsh
在35-，94-，和220-GHz的频率，并与恒星晶体，六边形板，和列的电磁散射特性的几个子弹花状冰晶形式的计算评估。其中一颗子弹晶体是四分支的平面晶体，另外两颗是六分支和八分支的空间晶体。使用两种取向模型，一种代表高度取向的晶体，考虑侧面和垂直入射方向，另一种代表：随机取向的晶体（入射方向不影响这种情况）。据观察，线性退偏振比（LDR），以及共偏振相关系数（/spl rho//sub h/spl nu//），可以用来区分列从平面（包括板和恒星晶体）和空间晶体的基础上，它们的值在垂直入射或其趋势作为仰角的函数。对于随机取向的情况，LDR和/spl rho//sub h/spl nu//可以区分列与空间晶体（除了在220 GHz时大于1.2 mm的尺寸），但不能区分列与平面晶体。此外，LDR和Z/sub DR/（差分反射率）的仰角依赖性具有区分柱状、平面和空间晶体的潜力，其尺寸在220 GHz下为零点几毫米至2 mm，在94 GHz下为约1至2 mm。在35 GHz下，小于2 mm的空间晶体在Z/sub DR/和LDR特征方面类似于球形颗粒。高密度（0.9 g cm/sup-3/）和低密度（代表中空晶体）晶体模型的结果显示出LDR、Z/sub DR/、/spl rho//sub h/spl nu//和后向散射截面的值的显著差异。
The electromagnetic scattering characteristics of several bullet-rosette ice crystal forms are computationally evaluated at 35-, 94-, and 220-GHz frequencies and compared with those of stellar crystals, hexagonal plates, and columns. One of the bullet rosettes is a planar crystal with four branches, the other two are spatial rosettes with six and eight branches. Two orientation models are used, one represents highly oriented crystals for which side and vertical incidence directions are considered, and the other represents: randomly oriented crystals (the incidence direction does not affect this case). It is observed that the linear depolarization ratio (LDR), as well as the copolarized correlation coefficient (/spl rho//sub h/spl nu//), can be used to differentiate columns from planar (including plates and stellar crystals) and spatial crystals based on their values at vertical incidence or their trends as a function of the elevation angle. For the random orientation case, LDR and /spl rho//sub h/spl nu// can differentiate columns from spatial crystals (except for sizes larger than 1.2 mm at 220 GHz) but not from planar crystals. Furthermore, the elevation angle dependence of LDR and Z/sub DR/ (differential reflectivity) has the potential for differentiating columnar, planar, and spatial crystals for sizes from a few tenths of a millimeter to 2 mm at 220 GHz, and from about 1 to 2 mm at 94 GHz. At 35 GHz, spatial crystals smaller than 2-mm resemble spherical particles in terms of their Z/sub DR/ and LDR signatures. The results for high-density (0.9 g cm/sup -3/) and low-density (representing hollow crystals) crystal models show significant differences in the values of LDR, Z/sub DR/, /spl rho//sub h/spl nu//, and the backscattering cross sections.