A method for determining the single scattering albedo of clouds through observation of the internal scattered radiation field
A method for determining the single scattering albedo of clouds through observation of the internal scattered radiation field
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一种通过观测内部散射辐射场确定云单次散射反照率的方法
DOI：
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发表时间：
1981
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通讯作者：
M. King
中科院分区：
文献类型：
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作者：
M. King
本文提出了一种确定云在可见光和近红外波段的单次散射的方法。该程序比较的比率的天顶到最低点的传播强度在云层深处的辐射传输计算相同的测量。导出了内光强比与地面散射角、光学厚度、单次散射角和云不对称因子的关系式。单次散射的散射系数和云不对称因子以这样一种方式进入解，即这两个参数之间存在相似关系。因此，可以确定单次散射散射的精度由可以估计不对称因子的精度决定。描述了一种观测方法，由此飞机测量天顶和天底传播强度可用于确定作为波长函数的相似性参数。由于云的部分吸收取决于相似性参数，而不是单独地取决于单次散射的不对称性因子和不对称性因子，因此这对该方法没有严重的限制。一个精确的知识的地面散射和总光学厚度的云是不必要的解决方案，提供一个关联的波长的强度比是最大的保守散射。在这种内部校准方法下，云光学厚度的不确定性几乎可以补偿地面atbedo的不确定性。
A method is presented for determining the single scattering albedo of clouds at selected wavelengths in the visible and near-infrared wavelength regions. The procedure compares measurements of the ratio of the zenith to nadir propagating intensities deep within a cloud layer with radiative transfer computations of the same. Analytic formulas are derived which explicitly show the dependence of the internal intensity ratio on ground albedo, optical depth, single scattering albedo and cloud asymmetry factor. The single scattering albedo and cloud asymmetry factor enter the solution in such a way that a similarity relationship exists between these two parameters. As a result, the accuracy with which the single scattering albedo can be determined is dictated by the accuracy with which the asymmetry factor can be estimated. A method of observation is described whereby aircraft measurements of the zenith and nadir propagating intensities can be used to determine the similarity parameter as a function of wavelength. Since the fractional absorption of a cloud depends on the similarity parameter and not on the single scattering albedo and asymmetry factor separately, this poses no severe limitation to the method. An accurate knowledge of the ground albedo and total optical thickness of a cloud are unnecessary for a solution, provided one associates the wavelength for which the intensity ratio is a maximum with conservative scattering. Under this internal calibration approach, uncertainties in the ground atbedo are very nearly compensated by uncertainties in the cloud optical thickness.