Collaborative Research: Secondary Production of Ice in CUmuLus Experiment (SPICULE)

云可以包含液滴，冻结的晶体，或两者的混合物。 云是大部分是液态还是大部分是冻结的，对降水的可能性以及云与辐射的相互作用有着重大影响。 某些云可以在令人惊讶的短时间内从大部分液体变成完全冻结，这种现象被称为冰川作用。 云结冰的速度取决于二次结冰的现象，其中一些水滴的冻结会以级联的方式影响其他水滴。 有效的二次冰生产的确切机制仍然是科学界争论的焦点。 该项目将包括两架研究飞机在不同高度对同一云进行测量，以提供关于二次冰生成的更多数据。 该奖项的主要社会影响将是通过改善数值天气模型中冰过程的表现，从而改善天气预报和气候预测。 学生的参与将确保下一代科学家的教育和培训。研究团队将在西部大平原进行2020年夏季实地活动，以提高对积云中冰的形成和二次冰产生过程的理解。 研究人员认为，着名的Hallet-Mossup过程无法解释所观察到的积云的快速冰川作用，他们提供了另一种假设，即在强烈的积云上升气流中，-5C水平的过冷液滴的发展导致了针状物的产生/滴破裂二次冰的产生和-20C水平的快速冰川作用。 这项研究的目的是提供改进的定量测量与专用的飞行剖面，将尽量减少与初级成核和污染从老云的模糊性。 美国国家科学基金会/国家大气研究中心的C-130飞机将通过0 C层瞄准云下区域，而SPEC LearJet将从0 C层穿透云层并上升到高空。 重要的仪器包括科罗拉多州立大学的冰核探测器套件、SPEC 3V-CPI和怀俄明州大学的W波段云雷达。该奖项反映了NSF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。

Clouds can contain liquid droplets, frozen crystals, or a mixture of both. Whether a cloud is mostly liquid or mostly frozen has a significant impact on the potential for precipitation and the interaction of the cloud with radiation. Certain clouds can change from mostly liquid to entirely frozen in a surprisingly short amount of time, a phenomenon known as glaciation. The speed at which clouds glaciate is dependent on the phenomena of secondary ice production, where the freezing of some droplets affects others in a cascading fashion. The exact mechanism for efficient secondary ice production is still up for debate in the scientific community. This project will consist of two research aircraft making measurements of the same cloud at different heights to provide additional data on secondary ice production. The main societal impact of the award will be through the improvement of the representation of ice processes in numerical weather models, leading to better weather forecasts and climate projections. Student involvement will ensure the education and training of the next generation of scientists.The research team will conduct a summer 2020 field campaign in the western Great Plains to improve understanding of the processes involved in ice initiation and secondary ice production in cumulus clouds. The investigators argue that the well-known Hallet-Mossup process is not able to explain the observed rapid glaciation of cumulus clouds, and they offer the alternative hypothesis that the development of supercooled liquid droplets at the -5C level in strong cumulus updrafts leads to a spicule production/drop fracturing secondary ice production and rapid glaciation by the -20C level. The study is designed to provide improved quantitative measurements with dedicated flight profiles that will minimize ambiguity associated with primary nucleation and contamination from older clouds. The NSF/National Center for Atmospheric Research C-130 aircraft would target the below cloud region through the 0C level and the SPEC LearJet would penetrate the cloud from the 0C level and up in altitude. Important instruments include the Colorado State University suite of ice nuclei probes, the SPEC 3V-CPI and the University of Wyoming W-band cloud radar.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.