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

云中可以含有液滴、冻结晶体或两者的混合物。云是主要是液态的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都有重大影响。某些云可以在令人惊讶的短时间内从主要是液体变成完全冻结，这一现象被称为冰川。云层冰化的速度取决于次生冰产生的现象，在这种现象中，一些液滴的冻结以一种级联的方式影响其他液滴。在科学界，高效二次冰生产的确切机制仍然存在争议。该项目将由两架研究飞机组成，对同一云在不同高度进行测量，以提供更多关于二次冰生产的数据。该奖项的主要社会影响将是通过改进数值天气模型中冰过程的表示，从而产生更好的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。研究小组将在2020年夏季在大平原西部进行实地考察，以提高对积云中冰的形成和次生冰产生过程的理解。研究人员认为，众所周知的Hallet-Mossup过程不能解释观测到的积云快速冰化现象，他们提出了另一种假设，即在强积云上升气流中，在-5摄氏度水平上过冷液滴的发展导致针状物的产生/液滴破裂，二次冰的产生和冰川在-20摄氏度水平的快速冰化。这项研究的目的是通过专用的飞行剖面提供改进的定量测量，将与初级成核和旧云污染相关的模糊性降至最低。NSF/国家大气研究中心的C-130飞机将通过0C级别瞄准云层以下区域，SPEC Learjet将从0C级别和更高的高度穿透云层。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和怀俄明大学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智力优势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.