Horizontal radiative fluxes in clouds and accuracy of the independent pixel approximation at absorbing wavelengths
Horizontal radiative fluxes in clouds and accuracy of the independent pixel approximation at absorbing wavelengths
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云中的水平辐射通量和吸收波长下独立像素近似的精度
DOI：
10.1029/1999gl900306
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发表时间：
1999
影响因子：
5.2
通讯作者：
Robert F. Cahalan
中科院分区：
文献类型：
--
作者：
A. Marchak;L. Oreopoulos;A. Davis;W. Wiscombe;Robert F. Cahalan
对于吸收波长，我们讨论了云中水平太阳辐射通量对单个像素的传统平面平行辐射传输计算精度的影响，称为独立像素近似（IPA）。垂直积分的水平通量可以表示为三个分量的总和：反射率、透射率和吸收率的IPA精度。我们表明，IPA的反射率精度总是随着吸收的增加而提高，而IPA的透射率精度对吸收的变化不太敏感：相对于非吸收情况，它可能首先在弱吸收时恶化，然后在强吸收波长时再次提高。吸收率的IPA精度总是随着吸收的增加而降低。
For absorbing wavelengths, we discuss the effect of horizontal solar radiative fluxes in clouds on the accuracy of a conventional plane‐parallel radiative transfer calculation for a single pixel, known as the Independent Pixel Approximation (IPA). Vertically integrated horizontal fluxes can be represented as a sum of three components: the IPA accuracies for reflectance, transmittance and absorptance. We show that IPA accuracy for reflectance always improves with more absorption, while the IPA accuracy for transmittance is less sensitive to the changes in absorption: with respect to the non‐absorbing case, it may first deteriorate for weak absorption and then improve again for strongly absorbing wavelengths. IPA accuracy for absorptance always deteriorates with more absorption.