AGS-PRF: Hygroscopicity of Secondary Organic Aerosols Formed via Aqueous Reactions

该项目旨在更好地描述一个关键的大气气溶胶成分，二次有机气溶胶（SOA）的气候影响，这有助于自然和人为气溶胶浓度。重点是SOA对暖云形成的影响。目前的模型，基于室实验，侧重于生产气溶胶的气相氧化过程中，往往低估的质量浓度和环境有机气溶胶的氧化程度。越来越多的证据表明，SOA通过水相反应（aqSOA）在云中或水合霾颗粒中形成，可以调和这些差距：这些水相反应已被证明在实验室的大气条件下进行，反应产物是高度氧化的。虽然aqSOA的吸湿性，一个衡量粒子参与云滴形成或云凝结成核（CCN）活动的能力，预计由于其高度氧化的组成是高的，很少有研究已经证实了这种关系，以评估其气候影响。本研究将首次将aqSOA的CCN活性、组分极性和组成联系起来。一种新的分析方法将被应用于确定CCN活性的AQSOA作为组件极性的函数，提供新的见解，许多化学物种的整体吸湿性的未解决的贡献。使用高分辨率飞行时间气溶胶质谱仪获得的气溶胶数据的元素分析将用于评估极性和吸湿性如何与气溶胶相中的氧：碳比相关。该研究将在Sonia Kresthweis教授的指导下在科罗拉多州立大学（CSU）进行。就更广泛的影响而言，该项目的结果将有助于改善大气有机气溶胶的全球预算和有机气溶胶气候影响的代表性。此外，主要研究者将积极参与CSU的教育活动，包括担任关于负责任研究行为的研究生课程的讨论领导者。首席研究员还将通过NSF赞助的CSU大气过程多尺度建模中心担任实习生的研究导师。

This project seeks better characterization of the climatic impact of a key atmospheric aerosol component, secondary organic aerosol (SOA), which contributes to both natural and anthropogenic aerosol concentrations. The focus is on the impacts of SOA on warm cloud formation. Current models, based on chamber experiments that focused on production of aerosols from gas-phase oxidation processes, tend to underpredict the mass concentrations and the extent of oxygenation of ambient organic aerosols. Growing evidence suggests that SOA formed in clouds or in hydrated haze particles via aqueous reactions (aqSOA) may reconcile these gaps: these aqueous reactions have been shown to proceed under atmospheric conditions in the laboratory, and reaction products are highly oxygenated. Although aqSOA hygroscopicity, a measure of a particle's ability to participate in cloud drop formation or cloud condensation nucleating (CCN) activity, is expected to be high due to its highly oxidized composition, few studies have confirmed this relationship to evaluate its climatic impact. This study will correlate CCN activity of aqSOA, component polarity, and composition for the first time. A new analytical method will be applied for determination of CCN activity of aqSOA as a function of component polarity, providing new insights on the unresolved contribution of many chemical species to overall hygroscopicity. Elemental analysis of aerosol data obtained using a high-resolution time-of-flight aerosol mass spectrometer will be used to evaluate how polarity and hygroscopicity relate to oxygen:carbon ratios in the aerosol phase. The work will be conducted at Colorado State University (CSU) under the mentorship of Prof. Sonia Kreidenweis.In terms of broader impacts, the results of this project will help improve the global budget of atmospheric organic aerosols and the representation of organic aerosol climate impacts. Also, the principal investigator will be actively involved in educational activities at CSU including serving as a discussion leader for a graduate level course on responsible conduct of research. The principal investigator will also be a research mentor to interns via the NSF-sponsored Center for Multiscale Modeling of Atmospheric Processes at CSU.