Collaborative Research: Coastal Cloud Chemistry during the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE-CCC)

这个项目的重点是云化学的研究，以支持改进云的形成如何在气候模型中表示。一套先进的化学测量将在斯克里普斯码头和附近的索莱达山进行，以加强能源部的东太平洋云气溶胶降水实验（EPCAPE）活动，该实验将于2023年2月至2024年1月在加州拉霍亚进行。这一努力将提供前所未有的云化学过程特征，预计将有助于减少气候模式预测中的主要不确定性。该项目通过利用单粒子质谱技术、小型化静态热梯度云凝结核（CCN）仪器以及用于测量新生云滴（OH“爆发”）中形成的水羟基（OH）自由基的定制设计仪器，为EPCAPE增加了先进的云化学表征。采样策略可以验证以下假设：(1)被活化为云滴的气溶胶种群子集在化学上与未活化的颗粒不同，并且通过添加可在单颗粒质量片段中识别的水氧化成分进一步区分其大小分辨的化学成分。化学变化降低了粒子后续活化所需的活化过饱和，这反过来可能影响云结构和液滴分布。(2)通过剥落去除的气相化合物将通过提高摄取过程中的水溶性来降低每个颗粒活化所需的过饱和。预期影响将取决于污染影响的程度、气体种类的组成和浓度以及颗粒大小。(3)云循环间隔时间越长，粒子OH爆发量越大，因此云循环过程中粒子化学成分变化越大。氢氧根爆发的活动，加上气相物质的可用性，将解释在云事件之间观察到的化学变化的大部分变化。这项工作包括对仪器维护和测量分析方面的研究生和本科生进行培训，为进行大气研究的下一代科学家做好准备。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project is focused on the study of cloud chemistry in support of improvements in how cloud formation is represented in climate models. A suite of advanced chemical measurements will be made at the Scripps Pier and at nearby Mt. Soledad to augment the Department of Energy’s Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE) campaign to be conducted in La Jolla California from February 2023 to January 2024. This effort will provide an unprecedented characterization of cloud chemical processing that is expected to help reduce a major uncertainty in climate model predictions.This project adds advanced chemical characterization of clouds to EPCAPE by leveraging recent instrument developments of single-particle mass spectrometry techniques, miniaturized static thermal gradient cloud condensation nuclei (CCN) instruments, and a custom-designed instrument for measuring aqueous hydroxyl (OH) radicals formed in nascent cloud droplets (the OH "burst"). The sampling strategy enables testing of the following hypotheses: (1) The subset of the aerosol population that is activated to cloud droplets is chemically distinct from the unactivated particles, and its size-resolved chemical composition is further differentiated by adding aqueous-oxidized components that can be identified in single-particle mass fragments. The chemical changes lower the activation supersaturation required for subsequent activation of particles, which in turn may affect cloud structure and drop distributions. (2) Gas-phase compounds that are removed by denuding will lower the supersaturation required for activation of each particle by enhancing water solubility during the uptake process. The effect is expected to depend on the amount of pollution influence, on the composition and concentration of gaseous species, and on particle size. (3) Particles with longer times between cloud cycles will produce a larger OH burst, and as a result, larger changes to particle chemical composition during cloud cycling. The OH burst activity, together with the availability of gas phase species will explain much of the variation in the chemical changes observed between cloud events.This effort includes the training of graduate and undergraduate students in instrument maintenance and measurement analyses to prepare the next generation of scientists for conducting atmospheric research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.