The efficiency of secondary organic aerosol particles acting as ice-nucleating particles under mixed-phase cloud conditions
The efficiency of secondary organic aerosol particles acting as ice-nucleating particles under mixed-phase cloud conditions
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DOI：
10.5194/acp-18-9393-2018
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发表时间：
2018-07
影响因子：
6.3
通讯作者：
W. Frey;Dawei Hu;J. Dorsey;M. Alfarra;A. Pajunoja;A. Virtanen;P. Connolly;G. Mcfiggans
中科院分区：
文献类型：
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作者：
W. Frey;Dawei Hu;J. Dorsey;M. Alfarra;A. Pajunoja;A. Virtanen;P. Connolly;G. Mcfiggans
抽象的。在(热带)上对流层卷云的寒冷条件下，二次有机气溶胶(SOA)粒子被发现是有效的冰核粒子。它们是否也能像在混合相云中发现的那样，在稍微温暖的条件下有效地启动冰冻，目前还不确定。在这里，我们结合曼彻斯特气溶胶小室和曼彻斯特冰云小室，研究了光化学产生的SOA粒子的成冰能力。测试了三个类似于生物和人为颗粒以及不同相态的颗粒的SOA系统。它们分别是α-蒎烯、正十七烷和1，3，5-三甲苯。气溶胶粒子形成后，被转移到云室，在那里进行随后的准绝热云激活实验。此外，还考察了硫酸铵和高岭石的结冰能力，为实验装置的验证提供了参考。云是在−20到−28.6∘C的温度范围内形成的，只有使用尘埃颗粒的参考实验显示了冰核的证据。在其他任何实验中都没有观察到冰粒。因此，我们得出结论，在所报道的实验条件下产生的SOA粒子不是在混合相云条件下从液体饱和开始的有效的冰核粒子。
Abstract. Secondary organic aerosol (SOA) particles have been found to be efficient ice-nucleating particles under the cold conditions of (tropical) upper-tropospheric cirrus clouds. Whether they also are efficient at initiating freezing under slightly warmer conditions as found in mixed-phase clouds remains undetermined. Here, we study the ice-nucleating ability of photochemically produced SOA particles with the combination of the Manchester Aerosol Chamber and Manchester Ice Cloud Chamber. Three SOA systems were tested resembling biogenic and anthropogenic particles as well as particles of different phase state. These are namely α-pinene, heptadecane, and 1,3,5-trimethylbenzene. After the aerosol particles were formed, they were transferred into the cloud chamber, where subsequent quasi-adiabatic cloud activation experiments were performed. Additionally, the ice-forming abilities of ammonium sulfate and kaolinite were investigated as a reference to test the experimental setup. Clouds were formed in the temperature range of −20 to −28.6 ∘C. Only the reference experiment using dust particles showed evidence of ice nucleation. No ice particles were observed in any other experiment. Thus, we conclude that SOA particles produced under the conditions of the reported experiments are not efficient ice-nucleating particles starting at liquid saturation under mixed-phase cloud conditions.