Aerosol forcing uncertainty represents the largest climate forcing uncertainty overall. Its magnitude has remained virtually undiminished over the past 20 years despite considerable advances in understanding most of the key contributing elements. Recent work has produced modest increases only in the confidence of the uncertainty estimate itself. This review summarizes the contributions toward reducing the uncertainty in the aerosol forcing of climate made by satellite observations, measurements taken within the atmosphere, as well as modeling and data assimilation. We adopt a more measurement-oriented perspective than most reviews of the subject in assessing the strengths and limitations of each; gaps and possible ways to fill them are considered. Currently planned programs supporting advanced, global-scale satellite and surface-based aerosol, cloud, and precursor gas observations, climate modeling, and intensive field campaigns aimed at characterizing the underlying physical and chemical processes involved, are all essential. But in addition, new efforts are needed: (a) to obtain systematic aircraft in situ measurements capturing the multi-variate probability distribution functions of particle optical, microphysical, and chemical properties (and associated uncertainty estimates), as well as co-variability with meteorology, for the major aerosol airmass types; (b) to conceive, develop, and implement a suborbital (aircraft plus surface-based) program aimed at systematically quantifying the cloud-scale microphysics, cloud optical properties, and cloud-related vertical velocities associated with aerosol-cloud interactions; and (c) to focus much more research on integrating the unique contributions of satellite observations, suborbital measurements, and modeling, to reduce the persistent uncertainty in aerosol climate forcing.

中文翻译：

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通过将模型与卫星和大气内观测相结合来减少气溶胶强迫的不确定性：三条路

气溶胶强迫的不确定性代表了总体上最大的气候强迫不确定性。在过去 20 年中，尽管对大多数关键促成因素的理解取得了相当大的进步，但其规模几乎没有减弱。最近的工作仅对不确定性估计本身的置信度产生了适度的增加。这篇综述总结了通过卫星观测、在大气中进行的测量以及建模和数据同化对减少气候气溶胶强迫的不确定性所做的贡献。在评估每个主题的优势和局限性时，我们采用比大多数主题评论更注重测量的观点；考虑了差距和填补这些差距的可能方法。目前计划支持先进的全球规模卫星和地基气溶胶的计划，云和前体气体观测、气候建模和旨在表征所涉及的基本物理和化学过程的密集实地活动都是必不可少的。但除此之外，还需要做出新的努力：(a) 获得系统的飞机原位测量，捕捉粒子光学、微物理和化学特性（以及相关的不确定性估计）的多变量概率分布函数，以及与气象学，主要气溶胶气团类型；(b) 构思、开发和实施亚轨道（飞机加地基）计划，旨在系统地量化云尺度微物理学、云光学特性和与气溶胶-云相互作用相关的云相关垂直速度；