Aerosols have been proposed to influence precipitation rates and spatial patterns from scales of individual clouds to the globe. However, large uncertainty remains regarding the underlying mechanisms and importance of multiple effects across spatial and temporal scales. Here we review the evidence and scientific consensus behind these effects, categorized into radiative effects via modification of radiative fluxes and the energy balance, and microphysical effects via modification of cloud droplets and ice crystals. Broad consensus and strong theoretical evidence exist that aerosol radiative effects (aerosol–radiation interactions and aerosol–cloud interactions) act as drivers of precipitation changes because global mean precipitation is constrained by energetics and surface evaporation. Likewise, aerosol radiative effects cause well-documented shifts of large-scale precipitation patterns, such as the intertropical convergence zone. The extent of aerosol effects on precipitation at smaller scales is less clear. Although there is broad consensus and strong evidence that aerosol perturbations microphysically increase cloud droplet numbers and decrease droplet sizes, thereby slowing precipitation droplet formation, the overall aerosol effect on precipitation across scales remains highly uncertain. Global cloud-resolving models provide opportunities to investigate mechanisms that are currently not well represented in global climate models and to robustly connect local effects with larger scales. This will increase our confidence in predicted impacts of climate change.

有人提出，气溶胶会影响从单个云层到全球范围内的降水率和空间模式。然而，关于跨空间和时间尺度的多重效应的潜在机制和重要性仍然存在很大的不确定性。在这里，我们回顾了这些效应背后的证据和科学共识，将其分为通过改变辐射通量和能量平衡而产生的辐射效应，以及通过改变云滴和冰晶而产生的微物理效应。广泛的共识和强有力的理论证据表明，气溶胶辐射效应（气溶胶-辐射相互作用和气溶胶-云相互作用）是降水变化的驱动因素，因为全球平均降水受到能量和表面蒸发的限制。同样，气溶胶辐射效应会导致大规模降水模式发生有据可查的变化，例如热带辐合带。气溶胶对小尺度降水的影响程度尚不清楚。尽管有广泛的共识和强有力的证据表明，气溶胶扰动在微观物理上增加了云滴数量并减小了液滴尺寸，从而减缓了降水滴的形成，但气溶胶对跨尺度降水的总体影响仍然高度不确定。全球云解析模型提供了研究目前在全球气候模型中未得到很好体现的机制的机会，并将局部影响与更大规模联系起来。这将增强我们对气候变化预测影响的信心。