The influence of entrainment, a key process characterized by the entrainment rate in cumulus parameterization, on aerosol-cloud interactions has been widely recognized. However, despite qualitative links established between entrainment and aerosol loading, a quantitative relationship based on observational evidence remains elusive. This study utilizes aircraft observations of cumulus clouds during two field campaigns to determine the quantitative relationship between entrainment rate and aerosol loading. In both campaigns, the entrainment rate is negatively correlated with aerosol loading. It is speculated that increased aerosol loading enhances cloud edge droplet evaporation, which leads to increased buoyancy and vertical velocity within the cloud, thereby reducing the entrainment rate. Further analysis shows that the response of entrainment rate to aerosol perturbations is more significant in smaller cumulus clouds with weak buoyancy and less pronounced under opposite conditions. These findings shed new light on improving the description of aerosol-cloud interactions in cumulus parameterizations.

中文翻译：

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飞机观测揭示了积云夹带率与气溶胶载荷之间的关系


夹带（以积云参数化中的夹带率为特征的关键过程）对气溶胶-云相互作用的影响已得到广泛认可。然而，尽管夹带和气溶胶负载之间建立了定性联系，但基于观测证据的定量关系仍然难以捉摸。本研究利用飞机在两次野外活动期间对积云的观测来确定夹带率和气溶胶负荷之间的定量关系。在这两个活动中，夹带率与气溶胶负荷呈负相关。据推测，气溶胶负荷的增加增强了云边缘液滴蒸发，从而导致云内的浮力和垂直速度增加，从而降低了夹带率。进一步分析表明，夹带速率对气溶胶扰动的响应在浮力较弱的较小积云中更为显著，而在相反条件下则不那么明显。这些发现为改进积云参数化中气溶胶-云相互作用的描述提供了新的思路。