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

该奖项全部或部分由2021年美国救援计划法案（公法117-2）资助。该项目将研究全球海洋中长寿命相干中尺度涡旋的流体输送，包括其相干核心内的体积，涡旋外围的瞬时捕获流体，以及环境水团中由于涡旋影响而产生的搅拌效应。该项目将依赖于一种新的涡流识别分析技术（由PI在先前的工作中开发），该技术应用于全球表面漂移数据集和历史上一组声学跟踪的地下浮子的现场测量。这与网格化卫星产品中涡流检测的通常方法不同，而是依赖于信号处理技术对浮动轨迹数据的调整。以前的研究基于这样的网格产品大大低估了涡流的数量，高估了涡流的大小和运输的水被困在其中。数据分析将辅以理论理想化和现实的数值模拟。这项工作将解决所观察到的无处不在的相干涡实际上完成的大尺度流动的影响。这是一个具有社会重要性的问题，因为它关系到为大气环流模式制定精确的次网格尺度参数化。该项目将推进拉格朗日数据的可行使用的边界，从而为社区提供新的涡流检查工具。该项目将为基础和高级海洋学数据分析的免费在线课程提供支持和信息，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的拉丁裔科学家，他将开发一个与该项目相关的本科水平的教学模块。该项目将对相干涡旋在驱动流体输送中的作用进行明确的研究，以现场拉格朗日观测中的显著涡旋检测为起点。的检测方法，称为涡信号提取，恢复随时间变化的振荡信号分量从拉格朗日轨迹，而不要求的振荡是严格的周期性。现有数据包括大约24，000个全球表面漂移轨迹，以及来自历史上一组涡流分辨浮子的另外3，000个地下轨迹，这两个数据集都是NOAA数据集。数据分析将通过理想化和超高分辨率的现实建模来补充。这些组件将被用来探索从拉格朗日的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，并调查感兴趣的运输过程的动力学。该项目将分三个部分进行：（一）直接和间接涡驱动输送的动力学，（二）涡的可观测性问题，和（三）全球估计。预期的产品将是新的全球估计的相干涡流特性，人口和边界，通过统计建模的长期和短暂的捕获物理学的更好的理解。该项目将进一步提供一个校准过程，通过该过程，遥感特征可以更准确地映射到流体结构上，水文分析将把区域运输估计转换为质量transmission.This奖项反映了NSF的法定使命，并已被认为是值得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的支持。

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.