Plass G N, Kattawar G W
Appl Opt. 1971 Apr 1;10(4):738-48. doi: 10.1364/AO.10.000738.
The radiance and polarization are calculated at six wavelengths from 0.7 micro to 6.05 micro for the photons reflected from and transmitted through two model clouds representing water and ice clouds with modal radii of 12 micro and 50 micro, respectively. The single scattering matrix is obtained from the Mie theory for spherical particles from the measured values of the complex index of refraction for water and ice. Multiple scattering to all orders is taken into account by a Monte Carlo technique which computes the exact three-dimensional paths of the photons. The upward and downward radiance and polarization are given as a function of optical thickness for each cloud model. The mean optical path of the photon, the cloud albedo, and the flux at the lower and upper boundaries are also given. The reflected radiance is considerably less for the ice than for the nimbostatus (water) model at all angles at most infrared wavelengths, particularly at wavelengths of 1.7 micro, 2.1 micro, and 3.5 micro. The polarization of the reflected photons is often very much greater for the ice than for the nimbostratus model, particularly at wavelengths of 1.7 micro, 2.1 micro, and 3.5 micro. These differences may be used in order to discriminate between water and ice clouds from measurements of the reflected radiation.
针对分别代表水云和冰云、模态半径分别为12微米和50微米的两个模型云反射和透射的光子，在0.7微米至6.05微米的六个波长处计算了辐射率和偏振度。单次散射矩阵由米氏理论根据水和冰的复折射率测量值得出，用于球形粒子。通过蒙特卡罗技术考虑了所有阶次的多次散射，该技术计算光子的精确三维路径。给出了每个云模型的向上和向下辐射率及偏振度随光学厚度的函数关系。还给出了光子的平均光学路径、云反照率以及上下边界处的通量。在大多数红外波长的所有角度下，冰云的反射辐射率比雨层云（水云）模型的反射辐射率要低得多，特别是在1.7微米、2.1微米和3.5微米波长处。冰云反射光子的偏振度通常比雨层云模型的偏振度大得多，特别是在1.7微米、2.1微米和3.5微米波长处。这些差异可用于根据反射辐射的测量来区分水云和冰云。
