Gordon H R, Castaño D J
Appl Opt. 1989 Apr 1;28(7):1320-6. doi: 10.1364/AO.28.001320.
For measurement of aerosols over the ocean, the total radiance L(t) backscattered from the top of a stratified atmosphere which contains both stratospheric and tropospheric aerosols of various types has been computed. A similar computation is carried out for an aerosol-free atmosphere yielding the Rayleigh scattered radiance L(r). The difference L(t) - L(r) is shown to be linearly related to the radiance L(as), which the aerosol would produce in the single scattering approximation. This greatly simplifies the application of aerosol models to aerosol analysis by satellite since adding to, or in some way changing, the aerosol model requires no additional multiple scattering computations. In fact, the only multiple computations required for aerosol analysis are those for determining L(r), which can be performed once and for all. The computations are explicitly applied to Band 4 of the CZCS, which, because of its high radiometric sensitivity and excellent calibration, is ideal for studying aerosols over the ocean. Specifically, the constant A in the relationship L(as) = A(-1)(L(t) - L(r)) is given as a function of position along the scan for four typical orbital-solar position scenarios. The computations show that L(as) can be retrieved from L(t) - L(r) with an average error of no more than 5-7% except at the very edges of the scan.
为了测量海洋上空的气溶胶，已计算出从包含各种平流层和对流层气溶胶的分层大气顶部反向散射的总辐射亮度L(t)。对无气溶胶大气进行了类似计算，得出瑞利散射辐射亮度L(r)。结果表明，L(t) - L(r)与气溶胶在单次散射近似下产生的辐射亮度L(as)呈线性相关。这极大地简化了气溶胶模型在卫星气溶胶分析中的应用，因为增加或在某种程度上改变气溶胶模型不需要额外的多次散射计算。实际上，气溶胶分析所需的唯一多次计算是用于确定L(r)的计算，而这只需进行一次即可。这些计算被明确应用于海岸带彩色扫描仪（CZCS）的第4波段，该波段由于其高辐射灵敏度和出色的校准，是研究海洋上空气溶胶的理想波段。具体而言，对于四种典型的轨道-太阳位置情况，给出了L(as) = A(-1)(L(t) - L(r))关系中常数A作为沿扫描位置的函数。计算表明，除了在扫描的最边缘处，L(as)可以从L(t) - L(r)中反演出来，平均误差不超过5-7%。
