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

该项目的重点是云化学研究，以支持改进云形成在气候模型中的表现方式。一套先进的化学测量将在斯克里普斯码头和附近的山。Soledad将加强能源部的东太平洋云气溶胶降水实验（EPCAPE）活动，该活动将于2023年2月至2024年1月在拉霍亚加州进行。这项工作将提供一个前所未有的云化学过程的表征，预计将有助于减少气候模式预测中的主要不确定性。该项目通过利用最近的单粒子质谱技术，小型化静态热梯度云凝结核（CCN）仪器，和一个定制设计的仪器，用于测量在新生云滴中形成的水溶性羟基（OH）自由基（OH“爆发”）。采样策略使得能够测试以下假设：（1）被激活为云滴的气溶胶群体的子集在化学上不同于未激活的颗粒，并且其尺寸分辨的化学成分通过添加可以在单颗粒质量碎片中识别的水性氧化成分而进一步区分。化学变化降低了随后粒子活化所需的活化过饱和度，这反过来又可能影响云结构和液滴分布。(2)通过剥蚀去除的气相化合物将通过在吸收过程中提高水溶性来降低每个颗粒活化所需的过饱和度。预计这种影响将取决于污染影响的程度、气态物质的成分和浓度以及颗粒的大小。(3)云周期之间的时间较长的粒子将产生更大的OH爆发，因此，在云周期期间粒子化学成分发生更大的变化。OH爆发活动，与气相物质的可用性一起，将解释在云事件之间观测到的化学变化的大部分变化。这一努力包括对研究生和本科生进行仪器维护和测量分析方面的培训，以使下一代科学家为进行大气研究做好准备。该奖项反映了NSF的法定使命，并被认为值得通过评估予以支持使用基金会的知识价值和更广泛的影响审查标准。

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.