Use of sky brightness measurements from ground for remote sensing of particulate polydispersions.
Use of sky brightness measurements from ground for remote sensing of particulate polydispersions.
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DOI：
10.1364/ao.35.002672
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发表时间：
1996-05
期刊：
影响因子：
1.9
通讯作者：
Teruyuki Nakajima;G. Tonna;Ruizhong Rao;P. Boi;Y. Kaufman;B. Holben
中科院分区：
文献类型：
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作者：
Teruyuki Nakajima;G. Tonna;Ruizhong Rao;P. Boi;Y. Kaufman;B. Holben
介绍了从太阳直射和散射辐射数据反演气溶胶粒径分布和光学厚度的软件代码SKYEAD.pack;用天空辐射计在0.369-1.048微米波长范围内进行测量。关于光学量的辐射传输问题的处理主要基于IMS（改进的多次和单次散射）方法，该方法使用用于截断气溶胶相函数的Δ-M近似，并校正一阶和二阶散射的解。线性和非线性反演方法均可用于反演粒度分布。改进的直接和散射辐射的校准方法，数据分析程序，从建议的代码的结果，和几个连接的问题进行了讨论。结果表明：（a）在输入参数正确的情况下，SKYRAD.pack程序能准确、有效地反演多种环境条件下的气溶胶特征：（B）当同时使用直射和散射太阳辐射数据时，气溶胶粒子的可探测半径范围约为0.03 ~ 10 μm;（c）除了检索气溶胶特征外，数据分析程序还允许确定三个输入参数的平均值（真实的和假想的气溶胶折射率，地面折射率）;（d）不需要对天空辐射计进行绝对校准，直接辐射和散射辐射的校准可利用实地数据进行;（e）非线性反演在较大的半径区间内给出了令人满意的结果，没有线性反演出现的不切实际的驼峰，但结果在很大程度上取决于第一猜测谱;（f）从模拟数据中反演的气溶胶特征与线性反演的给定数据相比，显示出更好的一致性。
The software code SKYEAD.pack for retrieval of aerosol size distribution and optical thickness from data of direct and diffuse solar radiation is described; measurements are carried out with sky radiometers in the wavelength range 0.369-1.048 µm. The treatment of the radiative transfer problem concerning the optical quantities is mainly based on the IMS (improved multiple and single scattering) method, which uses the delta-M approximation for the truncation of the aerosol phase function and corrects the solution for the first- and second-order scattering. Both linear and nonlinear inversion methods can be used for retrieving the size distribution. Improved calibration methods for both direct and diffuse radiation, the data-analysis procedure, the results from the proposed code, and several connected problems are discussed. The results can be summarized as follows: (a) the SKYRAD.pack code can retrieve the columnar aerosol features with accuracy and efficiency in several environmental situations, provided the input parameters are correctly given; (b) when data of both direct and diffuse solar radiation are used, the detectable radius interval for aerosol particles is approximately from 0.03 to 10 µm; (c) besides the retrieval of the aerosol features, the data-analysis procedure also permits the determination of average values for three input parameters (real and imaginary aerosol refractive index, ground albedo) from the optical data; (d) absolute calibrations for the sky radiometer are not needed, and calibrations for direct and diffuse radiation can be carried out with field data; (e) the nonlinear inversion gives satisfactory results in a larger radius interval, without the unrealistic humps that occur with the linear inversion, but the results strongly depend on the first-guess spectrum; (f) aerosol features retrieved from simulated data showed a better agreement with the given data for the linear inversion than for the nonlinear inversion.