Abstract Clear-sky irradiance (CSI) modeling constitutes an essential component of the evaluation of the solar resource at any location, and is involved in a large number of applications. In solar applications, most common CSI models provide broadband irradiance predictions based on a number of simplifications and/or empirical components compared to the rigorous radiative transfer models used in atmospheric sciences. Thus, these common CSI models have to undergo continuous quality assurance evaluations to delineate the range of validity of such simplifications. Traditionally, these evaluations have consisted in direct comparisons against high-quality ground observations. A review of 36 such validation studies of the literature is provided here, highlighting which CSI models were recommended over different climatic areas. This review underlines the difficulty of generalizing these results due to a number of methodological difficulties. In particular, the availability of ground observations is limited and does not cover the full extent of the atmospheric conditions over which the CSI models are regularly operated. In this review study, fifteen of the most highly cited CSI models of the literature are compared to each other using a global synthetic input database built from atmospheric reanalyses. It guarantees that most of the operating conditions of CSI models are potentially covered. The study focuses on the global horizontal (GHI) and direct normal (DNI) irradiance predictions of the CSI models. Overall, a better agreement for GHI than for DNI is found. The largest inter-model discrepancies span throughout Asia, the Middle East and central and northern Africa, precisely coinciding with some of the regions with the highest interest for solar energy applications. The most important sources of discrepancies are traced down to high loads of aerosols, high site elevations, and low solar altitudes. Usage of the Linke turbidity factor as input to a popular type of simplified CSI model is found to be a significant source of uncertainty, preventing accurate simultaneous predictions of GHI and DNI. Other models, which tend to mispredict GHI or DNI over, e.g., hazy areas, are identified.

中文翻译：

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晴天太阳辐射模型的全球相互比较：基于共识的对地球表面模拟的直接和全球辐照度分量的审查

摘要 晴空辐照度（CSI）建模是评估任何地点太阳能资源的重要组成部分，并涉及大量应用。在太阳能应用中，与大气科学中使用的严格辐射传输模型相比，最常见的 CSI 模型基于许多简化和/或经验成分提供宽带辐照度预测。因此，这些常见的 CSI 模型必须进行持续的质量保证评估，以划定此类简化的有效性范围。传统上，这些评估包括与高质量地面观测的直接比较。此处提供了对 36 项此类文献验证研究的回顾，重点介绍了在不同气候区域推荐的 CSI 模型。这篇综述强调了由于一些方法上的困难而难以概括这些结果。特别是，地面观测的可用性是有限的，并没有涵盖 CSI 模型定期运行的大气条件的全部范围。在这项审查研究中，使用根据大气再分析构建的全球合成输入数据库，对文献中引用率最高的 CSI 模型中的 15 种进行了相互比较。它保证了 CSI 模型的大部分操作条件都可能被覆盖。该研究侧重于 CSI 模型的全局水平 (GHI) 和直接法向 (DNI) 辐照度预测。总的来说，发现 GHI 的一致性比 DNI 更好。最大的模型间差异跨越整个亚洲、中东和非洲中部和北部，恰好与对太阳能应用最感兴趣的一些地区相吻合。差异的最重要来源可追溯到高气溶胶负载、高站点海拔和低太阳高度。使用 Linke 浊度因子作为流行类型的简化 CSI 模型的输入被发现是一个重要的不确定性来源，阻碍了 GHI 和 DNI 的准确同时预测。其他模型往往会错误预测 GHI 或 DNI，例如模糊区域。使用 Linke 浊度因子作为流行类型的简化 CSI 模型的输入被发现是一个重要的不确定性来源，阻碍了 GHI 和 DNI 的准确同时预测。其他模型往往会错误预测 GHI 或 DNI，例如模糊区域。使用 Linke 浊度因子作为流行类型的简化 CSI 模型的输入被发现是一个重要的不确定性来源，阻碍了 GHI 和 DNI 的准确同时预测。其他模型往往会错误预测 GHI 或 DNI，例如模糊区域。