Collaborative Research: Global eddy-driven transport estimated from in situ Lagrangian observations

合作研究：根据原位拉格朗日观测估计全球涡流驱动的输运

• 批准号: 2049576
• 负责人: Harper Simmons
• 金额: $ 4.85万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-15 至 2023-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2049576&HistoricalAwards=false
• 关键词: Collaborative; Research; Global; eddy; driven

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).This project will examine fluid transport by long-lived coherent mesoscale eddies in the global ocean, including volumes within their coherent cores, transiently trapped fluids in eddy peripheries, and stirring effects in the ambient watermasses due to eddy influence therein. The project would rely on a novel eddy-identifying analysis technique (developed in prior work by the PIs) applied to in-situ measurements from global surface drifter dataset and the historical set of acoustically-tracked subsurface floats. This is a departure from the usual approach of eddy detection in gridded satellite products, relying instead on the adaptation of signal processing techniques to float trajectory data. Prior studies based on such gridded products significantly underestimate numbers of eddies, and overestimate eddy sizes and transport of water trapped within them. Data analysis will be supplemented by theoretical idealized and realistic numerical modeling. This work will address what observed ubiquitous coherent eddies actually accomplish in terms of their effect on the large-scale flow. This is a question of societal importance because of its relevance for the development of accurate subgrid-scale parameterizations for general circulation models. The project will advance the boundaries of the viable use of Lagrangian data, and thus provide new tools for eddy examination to the community. The project will support and inform free online courses in fundamental and advanced oceanographic data analysis, so that that these state-of-the-art methodologies will be broadly accessible to the next generation of researchers. The project supports an early career latino scientist, who will develop an undergraduate-level teaching module related to this project.This project will produce a definitive study on the role of coherent eddies in driving fluid transport, taking significant eddy detections from in situ Lagrangian observations as the starting point. The detection method, called vortex signal extraction, recovers time-varying oscillatory signal components from Lagrangian trajectories, without a requirement for the oscillations to be strictly periodic. Available data include approximately 24,000 global surface drifter trajectories plus another 3,000 subsurface trajectories from an historical set of eddy-resolving floats, both NOAA datasets. Data analysis will be complemented by idealized and ultra-high-resolution realistic modeling. These components will be used to explore the subtleties of observing the eddy field from the Lagrangian perspective, to examine the theoretical properties of the eddy detection methods, and to investigate the dynamics of the transport processes of interest. The project will proceed in three branches: (i) dynamics of direct and indirect eddy-driven transport, (ii) the vortex observability problem, and (iii) global estimates. Anticipated products will be new global estimates of coherent eddy properties, populations, and boundaries through statistical modeling informed by an improved understanding of the physics of long-term and transitory trapping. The project will further provide a calibration process by which remotely-sensed features can be more accurately mapped onto fluid structures, and a hydrographic analysis will convert areal transport estimates into mass transports.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.

该奖项的全部或部分资金根据《2021 年美国救援计划法案》（公法 117-2）提供。该项目将研究全球海洋中长寿命相干中尺度涡流的流体输送，包括其相干核心内的体积、涡流外围短暂捕获的流体以及由于涡流影响而对周围水体产生的搅动效应。该项目将依赖于一种新颖的涡流识别分析技术（由 PI 之前的工作中开发），应用于全球表面漂移数据集和历史声学跟踪地下浮标组的现场测量。这与网格卫星产品中涡流检测的常用方法不同，而是依赖于信号处理技术对浮动轨迹数据的适应。先前基于此类网格产品的研究明显低估了涡流的数量，并高估了涡流的大小和其中捕获的水的传输。数据分析将得到理论理想化和现实数值模型的补充。这项工作将解决观察到的普遍存在的相干涡流在对大规模流动的影响方面实际完成的工作。这是一个具有社会重要性的问题，因为它与开发一般环流模型的精确亚网格尺度参数化相关。该项目将拓展拉格朗日数据的可行使用范围，从而为社区提供涡流检查的新工具。该项目将支持基础和高级海洋数据分析的免费在线课程并为其提供信息，以便下一代研究人员能够广泛使用这些最先进的方法。该项目支持一位早期职业生涯的拉丁裔科学家，他将开发与该项目相关的本科水平教学模块。该项目将以原位拉格朗日观测中的显着涡流检测为起点，对相干涡流在驱动流体传输中的作用进行明确的研究。这种检测方法称为涡旋信号提取，从拉格朗日轨迹中恢复时变振荡信号分量，而不要求振荡具有严格的周期性。可用数据包括大约 24,000 个全球表面漂流者轨迹以及来自一组历史涡流解析浮标的另外 3,000 个地下轨迹，这两个数据集都是 NOAA 数据集。数据分析将得到理想化和超高分辨率现实建模的补充。这些组件将用于探索从拉格朗日角度观察涡流场的微妙之处，检查涡流检测方法的理论特性，并研究感兴趣的传输过程的动力学。该项目将分三个分支进行：（i）直接和间接涡流驱动传输的动力学，（ii）涡旋可观测性问题，以及（iii）全球估计。预期的产品将是通过统计模型对相干涡流特性、种群和边界进行新的全球估计，该统计模型是通过对长期和短暂俘获物理学的深入了解而提供的。该项目将进一步提供校准过程，通过该过程可以将遥感特征更准确地映射到流体结构上，并且水文学分析将区域运输估计转换为质量运输。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。