Transfer of polarized infrared radiation in optically anisotropic media: application to horizontally oriented ice crystals
Transfer of polarized infrared radiation in optically anisotropic media: application to horizontally oriented ice crystals
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偏振红外辐射在光学各向异性介质中的传输：在水平取向冰晶中的应用
DOI：
10.1364/josaa.10.001243
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发表时间：
1993
影响因子：
1.9
通讯作者：
K. Liou
中科院分区：
文献类型：
--
作者：
Y. Takano;K. Liou
我们开发了一种计算光学各向异性介质中红外辐射偏振的理论，并具体应用于经常出现在卷云中的水平取向冰晶。在有关各向异性介质中热辐射传递的基本公式中考虑了发射和散射的贡献。首次给出了红外偏振公式中所要求的水平取向冰晶相矩阵元素的对称关系。采用几何射线追踪技术计算了水平取向六边形冰晶的相矩阵元。在10 μm波长的辐射和线偏振模式，是从卷云中涌现出来的，其中包含板和柱在二维空间中取向，并在物理术语中进行了讨论。从云底产生的向下极化为负，而从云顶产生的向上极化在近翼方向处最大值为正。这些极化构型与三维空间中包含随机取向冰晶的冰云产生的极化构型明显不同。鉴于这些结果，利用云层上方或下方的红外偏振测量来推断卷云中冰晶的方向特征似乎是可行的。
We have developed a theory for the computation of the polarization of infrared radiation in optically anisotropic media, with specific application to horizontally oriented ice crystals that frequently occur in cirrus clouds. Both emission and scattering contributions are accounted for in the basic formulation concerning the transfer of thermal radiation in anisotropic media. The symmetry relations of the phase matrix elements for horizontally oriented ice crystals, which are required in the infrared polarization formulations, are presented for the first time to our knowledge. Phase matrix elements for horizontally oriented hexagonal ice crystals are computed by a geometric ray-tracing technique. Radiance and linear-polarization patterns at a 10-μm wavelength that are emergent from cirrus clouds that contain plates and columns oriented in two-dimensional space are presented and discussed in physical terms. Downward polarization emergent from the cloud base is negative, while upward polarization emergent from the cloud top has a positive maximum value near the limb directions. These polarization configurations differ distinctly from the configurations of polarization emergent from ice clouds that contain randomly oriented ice crystals in three-dimensional space. Given these results, it appears feasible to infer the orientation characteristics of ice crystals in cirrus clouds with the use of infrared polarization measurements either above or below the cloud.