Collaborative Research: Aerosol Properties and Autoconversion during Cold-Air outbreak Experiment in the Sub-Arctic Region (CAESAR)

北极气候的变化速度比地球上任何地方都要快。气候预测表明，北极将继续变暖，但由于对北极云未来行为的疑问，不确定性出现了。一个主要不确定的领域是在冷空气爆发期间形成的云的性质，在冷空气爆发期间，北极冰层上的非常冷的气团向南移动，越过相对温暖的开阔海洋。该奖项将有助于在亚北极地区冷空气爆发实验（CAESAR）期间提供这些云（和降水）的观测数据以及海洋和大气之间的能量交换，该实验将于2024年春季在斯堪的纳维亚北部进行。在凯撒期间收集的观测资料将用于更好地了解冷空气爆发系统的特征，以及更广泛地了解北极气候系统，以便为气候模型和预测提供信息。该项目还将有助于改善与海军作战、商业航运和沿海社区密切相关的天气灾害预报。更广泛的领域努力包括为学生和早期职业科学家、国际合作和公众宣传提供重要机会。该奖项的一个具体目标是基于CAESAR项目为课程开发交互式工作表/笔记本。该奖项将有助于实现CAESAR项目的目标，即在一系列风和温度条件下，研究北极上游边界层不同气溶胶条件对冰形成、云液态水和雪生长机制的影响。特别是，通过该项目提供的测量将针对两个关键的知识空白：1)了解海洋边界层（MBL）云凝结核（CCN）源的预算，以及2)提供CCN限制气溶胶间接效应的观测约束。该项目将支持部署两台CCN计数器、一台扫描迁移率粒度仪（SMPS）、一台超高灵敏度气溶胶光谱仪（UHSAS）和一台单粒子烟灰光度计（SP2）。研究团队将提供两个增值产品来支持CAESAR的总体目标：质量控制的云凝结核激活谱，以支持气溶胶-云-降水模型研究人员；导出云滴数概率分布函数，以支持观测和建模同事。该项目的主要资金来自物理和动态气象学项目，部分资金来自北极自然科学项目。CAESAR观测资产的部署由大气研究和教育设施项目资助。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。

Arctic climate is changing at a faster pace than anywhere on Earth. Climate projections indicate that the Arctic will continue to warm, but uncertainties arise due to questions about the future behavior of Arctic clouds. An area of primary uncertainty is the properties of clouds that form during cold-air outbreaks, where very cold airmasses over the Arctic ice move southward over the relatively warm open ocean. This award will help to provide observational data of these clouds (and precipitation) and the exchange of energy between the ocean and atmosphere during the Cold-Air outbreak Experiment in the Sub-Arctic Region (CAESAR), which will be conducted in Spring 2024 out of northern Scandinavia. The observations collected during CAESAR will be used in an effort to better understand the characteristics of the cold-air outbreak system, and the Arctic climate system more broadly, in order to inform climate models and projections. The project will also help to improve forecasting of weather hazards with significant relevance to naval operations, commercial shipping, and coastal communities. The broader field effort includes significant opportunities for students and early-career scientists, international collaboration, and public outreach. One specific goal of this award is the development of interactive worksheets/notebooks for courses, based on the CAESAR project. This award will contribute to the CAESAR goal of examining the impact of varying aerosol conditions in the upstream Arctic boundary layer on ice initiation, cloud liquid water, and snow growth mechanisms in a range of wind and temperature regimes. In particular, the measurements provided through this project will target two critical knowledge gaps: 1) understanding the budget of marine boundary layer (MBL) cloud condensation nuclei (CCN) sources, and 2) providing observational constraints on CCN-limited aerosol indirect effect. The project will support the deployment of two CCN counters, a scanning mobility particle sizer (SMPS), an ultra-high sensitivity aerosol spectrometer (UHSAS), and a single particle soot photometer (SP2). The research team will contribute two value-added products to support the overall CAESAR objectives: quality-controlled cloud condensation nuclei activation spectra to support aerosol-cloud-precipitation modeling investigators and derived cloud droplet number probability distribution functions to support observational and modeling colleagues.Primary funding for this project comes from the Physical and Dynamic Meteorology program with partial funding from the Arctic Natural Sciences program. The deployment of observational assets for CAESAR is being funded by the Facilities for Atmospheric Research and Education program.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.