pstrongAbstract./strong The relationship between aerosol hygroscopicity and cloud droplet activation was studied at the Puijo measurement station in Kuopio, Finland, during the autumn 2014. The hygroscopic growth of 80, 120 and 150 span class="thinspace"/spannm particles was measured at 90span class="thinspace"/span% relative humidity with a hygroscopic tandem differential mobility analyzer. Typically, the growth factor (GF) distributions appeared bimodal with clearly distinguishable peaks around 1.0–1.1 and 1.4–1.6. However, the relative contribution of the two modes appeared highly variable reflecting the probable presence of fresh anthropogenic particle emissions. The hygroscopicity-dependent activation properties were estimated in a case study comprising four separate cloud events with varying characteristics. At 120 and 150span class="thinspace"/spannm, the activation efficiencies within the low- and high-GF modes varied between 0–34 and 57–83span class="thinspace"/span%, respectively, indicating that the less hygroscopic particles remained mostly non-activated, whereas the more hygroscopic mode was predominantly scavenged into cloud droplets. By modifying the measured GF distributions, it was estimated how the cloud droplet concentrations would change if all the particles belonged to the more hygroscopic group. According to i?o/i-K??hler simulations, the cloud droplet concentrations increased up to 70span class="thinspace"/span% when the possible feedback effects on effective peak supersaturation (between 0.16 and 0.29span class="thinspace"/span%) were assumed negligible. This is an indirect but clear illustration of the sensitivity of cloud formation to aerosol chemical composition./p.
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机译：> >摘要。2014年秋季，在芬兰Kuopio的Puijo测量站研究了气溶胶吸湿性与云滴活化之间的关系。吸湿性分别增长了80、120和150使用吸湿串联差动迁移率分析仪在90％的相对湿度下测量=“ thinspace”> nm粒子。通常，生长因子（GF）分布呈双峰分布，在1.0≤1.1和1.4≤1.6处具有明显可区分的峰。然而，两种模式的相对贡献似乎变化很大，反映了可能存在新鲜的人为颗粒排放。在包括四个具有不同特征的独立云事件的案例研究中，估计了与吸湿性有关的激活特性。在120和150 class =“ thinspace”> nm时，低GF模式和高GF模式下的激活效率在0至34和57至83 class =“ thinspace”> -K ?? hler模拟，当可能的反馈影响有效峰过饱和时（在两次之间），云滴浓度增加至70 class =“ thinspace”> 假设忽略了0.16和0.29 class =“ thinspace”> ％）。这是对云形成对气溶胶化学成分敏感性的间接但清晰的说明。。
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