Collaborative Research: Ice Supersaturation over the Southern Ocean and Antarctica, and its Role in Climate

冰的过饱和度在云的形成和发展过程中起着关键作用，它决定了冰、液、气三相的分配。在南大洋和南极洲，混合云和冰云之间的转换对云的辐射效应有显著影响。南极洲和南大洋等偏远地区的实地观测，特别是空中观测，历来采样不足。尽管人们对这些地区的云微物理特性给予了更多的关注，但在南半球高纬度地区，冰过饱和的分布和特征及其在当前和未来气候中的作用还没有得到充分的研究。本研究的主要目的之一是分析美国国家科学基金会和美国能源部最近赞助的三次主要实地活动的观测结果，这些活动提供了南大洋上空的密集现场、空中测量和南极洲麦默多站的地基观测。本项目将分析南大洋和南极洲上空的飞机和地基观测结果，并将观测结果与社区地球系统模型第二版（CESM 2）模拟结果进行比较。重点将是观测冰的过饱和度和混合相云和冰云中的相对湿度分布，以及它们与云的微观和宏观物理特性的关系。将观察结果与CESM 2模拟进行比较，以阐明模型偏倚。将对麦默多站的地面辐射和降水收支进行量化，并与CESM 2模拟进行比较，以提高南极气候（和南极气候预测）的真实性。我们的研究结果将发布给社区，以提高对云辐射效应和南半球高纬度地区水的质量传输的理解。模拟和观测之间的比较将为改进下一代CESM模式提供有价值的信息。PI Diao将在圣何塞州立大学（SJSU）开展两个教育/推广项目，包括一个独特的本科生研究项目，在机载仪器上进行动手实验，该奖项反映了NSF的法定使命，并通过使用基金会的知识产权进行评估，被认为值得支持。优点和更广泛的影响审查标准。

Ice supersaturation plays a key role in cloud formation and evolution, and it determines the partitioning among ice, liquid and vapor phases. Over the Southern Ocean and Antarctica, the transition between mixed-phase and ice clouds significantly impacts the radiative effects of clouds. Remote regions such as the Antarctica and Southern Ocean historically have been under-sampled by in-situ observations, especially by airborne observations. Even though more attention has been given to the cloud microphysical properties over these regions, the distribution and characteristics of ice supersaturation and its role in the current and future climate have not been fully investigated at the higher latitudes in the Southern Hemisphere. One of the main objectives of this study is to analyze observations from three recent major field campaigns sponsored by NSF and DOE, which provide intensive in-situ, airborne measurements over the Southern Ocean and ground-based observations at McMurdo station in Antarctica.This project will analyze aircraft-based and ground-based observations over the Southern Ocean and Antarctica, and compare the observations with the Community Earth System Model Version 2 (CESM2) simulations. The focus will be on the observations of ice supersaturation and the relative humidity distribution in mixed-phase and ice clouds, as well as their relationship with cloud micro- and macrophysical properties. Observations will be compared to CESM2 simulations to elucidate model biases. Surface radiation and the precipitation budget at the McMurdo station will be quantified and compared against the CESM2 simulations to improve the fidelity of the representation of Antarctic climate (and climate prediction over Antarctica). Results from our research will be released to the community for improving the understanding of cloud radiative effects and the mass transport of water in the high southern latitudes. Comparisons between the simulations and observations will provide valuable information for improving the next generation CESM model. Two education/outreach projects will be carried out by PI Diao at San Jose State University (SJSU), including a unique undergraduate student research project with hands-on laboratory work on an airborne instrument, and an outreach program that uses social media to broadcast news on polar research to the public.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.