Diagnosing the root causes of cloud feedback in climate models and reasons for inter-model disagreement is a necessary first step in understanding their wide variation in climate sensitivities. Here we bring together two analysis techniques that illuminate complementary aspects of cloud feedback. The first quantifies feedbacks from changes in cloud amount, altitude, and optical depth, while the second separates feedbacks due to cloud property changes within specific cloud regimes from those due to regime occurrence frequency changes. We find that in the global mean, shortwave cloud feedback averaged across ten models comes solely from a positive within-regime cloud amount feedback countered slightly by a negative within-regime optical depth feedback. These within-regime feedbacks are highly uniform: In nearly all regimes, locations, and models, cloud amount decreases and cloud albedo increases with warming. In contrast, global-mean across-regime components vary widely across models but are very small on average. This component, however, is dominant in setting the geographic structure of the shortwave cloud feedback: Thicker, more extensive cloud types increase at the expense of thinner, less extensive cloud types in the extratropics, and vice versa at low latitudes. The prominent negative extratropical optical depth feedback has contributions from both within- and across-regime components, suggesting that thermodynamic processes affecting cloud properties as well as dynamical processes that favor thicker cloud regimes are important. The feedback breakdown presented herein may provide additional targets for observational constraints by isolating cloud property feedbacks within specific regimes without the obfuscating effects of changing dynamics that may differ across timescales.

诊断气候模型中云反馈的根本原因和模型间分歧的原因是了解它们在气候敏感性方面的广泛变化的必要的第一步。在这里，我们汇集了两种分析技术，阐明了云反馈的互补方面。第一个量化来自云量、高度和光学深度变化的反馈，而第二个将由于特定云态内的云属性变化而产生的反馈与由于状态发生频率变化而产生的反馈分开。我们发现，在全球平均值中，十个模型的平均短波云反馈仅来自于正的区域内云量反馈，而负的区域内光学深度反馈则略微抵消了这一反馈。这些体制内反馈是高度一致的：在几乎所有体制、位置和模型中，云量减少，云反照率随着变暖而增加。相比之下，全球平均跨区域组件在模型之间差异很大，但平均而言非常小。然而，这个组成部分在设置短波云反馈的地理结构方面占主导地位：在温带地区，更厚、更广泛的云类型会以更薄、更不广泛的云类型为代价增加，反之亦然。显着的负温带光学深度反馈具有来自域内和跨域分量的贡献，这表明影响云特性的热力学过程以及有利于较厚云域的动力学过程很重要。