It is entirely apparent that an accurate estimation of global horizontal solar irradiance (GHI) does not guarantee an accurate estimation of its fundamental components. This basic perception motivates the present study, which evaluates the ability of the clear-sky solar irradiance models to accurately partition GHI into beam and diffuse components. Diverging from the traditional perspective, the diffuse fraction is assessed as an appropriate quantifier for the fractional part of GHI estimated by a clear-sky solar irradiance model as being diffuse. Acting as a quantifier, the diffuse fraction has the merit of isolating the uncertainty induced by aerosols in estimating the diffuse solar irradiance. The results of evaluating various clear-sky solar irradiance models show that many models consistently experience similar errors under high atmospheric turbidity. A strong influence of the atmospheric aerosol loading on the dissimilarities between the accuracies in estimating diffuse fraction and the corresponding diffuse solar irradiance is noticed. Our analysis of uncertainties in estimating the diffuse solar irradiance appears naturally as a sum of two terms: one encapsulating the ‘intrinsic’ error of the model, as quantified through errors in global solar irradiance, and the other encapsulating the aerosol modeling errors, as quantified through errors in diffuse fraction. For small atmospheric aerosol loading, the intrinsic errors of the model are dominant, while for high atmospheric aerosol loading the accurate modeling of the aerosols effect on GHI becomes critical.

很明显，对全球水平太阳辐照度 (GHI) 的准确估计并不能保证对其基本分量的准确估计。这种基本感知激发了本研究，该研究评估了晴空太阳辐照度模型将 GHI 准确划分为光束和漫射分量的能力。与传统观点不同，漫射分数被评估为适当的量化指标，用于由晴空太阳辐照度模型估计为漫射的 GHI 分数部分。作为一个量词，漫射分数具有隔离气溶胶在估计漫射太阳辐照度时引起的不确定性的优点。评估各种晴空太阳辐照度模型的结果表明，许多模型在高大气浊度下始终存在类似的误差。注意到大气气溶胶负载对估计漫射分数的准确性与相应的漫射太阳辐照度之间的差异有很大影响。我们对估计漫射太阳辐照度的不确定性的分析自然表现为两项的总和：一项包含模型的“内在”误差，通过全球太阳辐照度的误差量化，另一个封装气溶胶建模误差，量化通过弥散分数的错误。对于小的大气气溶胶载荷，模型的固有误差占主导地位，