A Vortex Census from Lagrangian Floats

有三个关键问题促使我们对拉格朗日浮标资料中的相干涡旋结构进行系统的重新研究：（i）迫切需要对涡旋参数化方案以及涡旋分辨数值模式与现场观测进行详细的比较; ㈡最近根据卫星测高，以前归因于Rossby波的大范围变率反而由于能量非线性中尺度涡动场而出现，内部签名，其中还在很大程度上是未知的;和（iii）越来越多的赞赏的重要，但多方面的作用相干涡流在流体输送和混合，包括涡流的尺度太小，无法准确地解决的高度。这些问题都指出，需要进行定量和综合研究的相干涡场及其大尺度的影响。与此同时，湍流研究强调，目前理解海洋涡旋场的能力受到缺乏客观和理论上令人信服的途径从现有拉格朗日数据推断欧拉“真理”的阻碍-也就是说，目前无法从拉格朗日平台进行正式的涡旋性质和种群普查。该项目将使用深拉格朗日声学跟踪浮子的历史数据集，在广泛的尺度范围内量化涡旋特征、种群和动力学影响。PI和合作者最近的一系列进展使这样的研究成为可能，在拉格朗日观测和涡旋动力学之间提供了一个新的特别直接的联系。这项研究的出发点是能够客观地和不确定性的估计，详细的时变方面的相干涡从个人拉格朗日轨迹提取。该项目的第一阶段利用这种方法来描述涡流，因为它们出现在数据中。在第二阶段，非均匀拉格朗日观测将用于形成估计的基础欧拉场，通过统计推断支持广泛的测试在理想化的准地转模拟。我们的目标是描述的涡流分布作为一个地理变化的随机场控制的少数参数。第三和最后阶段量化的涡场对大尺度流的影响-通过估计的速度和涡度分布，以及粒子和涡度运输与eddies.Intellectual Merit：这项研究将大大扩展和完善我们的理解相干涡在海洋中的作用。通过分离出构成“涡流通量”这一普遍现象的过程之一，这将是朝着理解和量化小规模“涡流”过程对大规模环流的影响这一更大目标迈出的重要一步。处理与卫星测高观测的联系问题特别及时。拉格朗日涡旋普查统计方法的建设和测试本身就是一个重要的contribution.Broader影响：这项工作的主要社会影响是它的潜在影响，我们预测长期气候变率的能力，立即提高我们的能力，以评估的保真度涡分辨和非涡分辨数值模式对原位数据。从事该项目的博士后研究人员将受益于接触新的分析技术和重要的拉格朗日数据集。浮动数据集的增值版本以及在该项目期间开发的所有分析软件将免费分发给社区，如所附数据管理计划所述;这些打开了海洋动力学的新窗口。

Three key issues motivate a systematic re-examination of coherent vortex structures in Lagrangian float data: (i) a pressing need for detailed comparison of eddy parameterization schemes, as well as of eddy-resolving numerical models, against in situ observations; (ii) the recent recognition, based on satellite altimetry, that a large swath of variability previously attributed to Rossby waves instead appears due to an energetic nonlinear mesoscale eddy field, the interior signature of which is as yet largely unknown; and (iii) an increasing appreciation of the important but multifaceted role coherent eddies play in fluid transport and mixing, including eddies at scales too small to be accurately resolved by altimetry. These issues all point to the need for a quantitative and integrated study of the coherent eddy field and its large-scale impacts. At the same time, turbulence studies emphasize that the current ability to understand the oceanic vortex field is hampered by the lack of an objective and theoretically compelling avenue for inferring Eulerian "truths" from available Lagrangian data - that is, the inability to currently perform a formal census of vortex properties and populations from the Lagrangian platform. This project will quantify vortex characteristics, populations, and dynamical impacts across a broad range of scales using the historical set of deep Lagrangian acoustically tracked floats. A series of recent advances by the PI and collaborators make such a study possible, providing a new and particularly direct link between Lagrangian observations and vortex dynamics. The starting point for the study is the ability to extract, objectively and with uncertainty estimates, detailed time-varying aspects of coherent eddies from individual Lagrangian trajectories. The first phase of this project utilizes this method to describe vortex currents as they appear in the data. In this second phase, inhomogenous Lagrangian observations will be used to form estimates of underlying Eulerian fields, via statistical inference backed by extensive testing within idealized quasigeostrophic simulations. The goal is to describe the vortex distribution as a geographically-varying random field controlled by a small number of parameters. The third and final phase quantifies impacts of the vortex field on the large-scale flow - by estimating the velocity and vorticity distributions as well as particle and vorticity transport associated with the eddies.Intellectual Merit: This study will substantially extend and refine our understanding of the role of coherent eddies in the ocean. It will be an important step towards the larger goal of understanding and quantifying the impact of small-scale "eddy" processes on the large-scale circulation, by isolating one of the processes that make up the general phenomenon of "eddy fluxes". Addressing the connection to observations from satellite altimetry is particularly timely. The construction and testing of a Lagrangian vortex census statistical methodology is itself an important contribution.Broader Impacts: A primary societal impact of this work is its potential impact on our ability to predict long-term climate variability by immediately increasing our ability to assess the fidelity of both eddy-resolving and non-eddy-resolving numerical models against in situ data. The postdoctoral researcher working on the project will benefit from exposure to novel analysis techniques and an important Lagrangian data set. Value-added versions of the float dataset, and all analysis software developed during this project, will be freely distributed to the community as described in the attached Data Management Plan; these open a new window into ocean dynamics.