Collaborative Research: Origin, Dynamics and Transport Characteristics of the Large-Scale Eddy-Driven Patterns

海洋中尺度变率的主要后果之一是在空间尺度上自发产生连贯的、缓慢演变的模式，其显著超过主要斜压不稳定的主要尺度。这些大尺度涡旋驱动型（LEDPs）是由中尺度涡旋产生和维持的，初步结果表明，大尺度涡旋驱动型（LEDPs）代表了海洋变化的很大一部分。此外，LEDPs可以在热量、盐度、生物地球化学示踪剂和动量的传输中发挥重要作用。因此，提高我们对这些间接涡旋效应的理解是至关重要的，特别是考虑到需要提高未来气候预测的准确性。将使用多尺度技术开发初级（中尺度）和次级（LEDP）结构之间相互作用的分析模型。多尺度方法非常适合这项任务，因为它们具有透明度，并且能够表示在不同空间和时间尺度上运行的现象之间的相互作用。该方法的新颖之处在于将多尺度方法应用于典型海流的原始涡型。这将有可能提供直接适用于观察和综合模型的ledp的现实描述，并通过观察和综合模型进行测试。理论模型将由具有越来越逼真程度的数值模拟层次来指导和验证，这也将侧重于ledp的特性和动力学。反过来，分析研究将广泛用于解释数值结果。这些方法的结合将揭示中尺度涡旋和涡流之间复杂的相互作用，这是单独通过数值模拟无法实现的，并描述由涡流作用引起的涡流传输特征。具体研究任务包括：分析LEDPs的形成机制；这些结构诱导示踪剂的各向异性色散；以及背景状态对LEDP动力学的影响。海洋变率在气候动力学中起着重要的作用，但人们对其知之甚少。横向涡旋转移是海洋输送热量、营养物、污染物和其他示踪剂的基本组成部分。因此，为了提高气候预测能力，最终带来社会效益，需要对海洋中涡流诱导的运输和低频变率的理解取得进展。从理论和模型运行中得出的推论将有助于解释观测数据集，并有助于规划旨在解释大尺度流量变化的未来观测策略。除了在海洋学上的重要性外，这项研究将对基础流体力学、地球物理学和气候科学产生重大影响。在此项目中，RSMAS的一名博士生和NPS的一名博士后将参与计划的研究活动，并发展涡旋海洋动力学方面的专业知识。此外，两名研究生（MS）海军学生将在NPS就与本提案相关的主题进行论文研究，而该项目无需支付任何费用。

One of the principal consequences of mesoscale variability in the ocean is the spontaneous generation of coherent, slowly evolving patterns on spatial scales significantly exceeding the dominant scale of primary baroclinic instability. These Large-Scale Eddy-Driven Patterns (LEDPs) are generated and maintained by mesoscale eddies and preliminary results indicate that LEDPs represent a substantial fraction of variability in the oceans. Furthermore, LEDPs can play an important role in the transport of heat, salinity, bio-geo-chemical tracers, and momentum. Thus, it is vital to improve our understanding of these indirect eddy effects, especially in light of the need for the increased accuracy of future climate projections.Analytical models for the interaction between primary (mesoscale) and secondary (LEDP) structures will be developed using multi-scale techniques. Multi-scale methods are ideally suited to this task due to their transparency and ability to represent interactions between phenomena operating on distinct spatial and temporal scales. The novelty of our approach lies in the application of multi-scale methods to the primary eddy patterns realized in typical oceanic flows. This will make it possible to offer a realistic description of LEDPs, directly applicable to, and testable by, observations and comprehensive models. Theoretical models will be guided and validated by a hierarchy of numerical simulations with an increasing degree of realism, which will also focus on the properties and dynamics of LEDPs. Analytical studies, in turn, will be used extensively for interpretation of the numerical results. The combination of these approaches will reveal the complex interplay between mesoscale eddies and LEDPs, not possible through numerical simulation alone, and describe the eddy transport characteristics induced by the action of LEDPs. Specific research tasks include the analysis of: the formation mechanisms of LEDPs; the anisotropic dispersion of tracers induced by these structures; and the effects of the background state on LEDP dynamics.Oceanic variability plays an important, but poorly understood role in climate dynamics. Lateral eddy transfer is a fundamental component of the oceanic transport heat, nutrients, pollutants and other tracers. Thus, advances in the understanding of eddy-induced transport and low frequency variability in the oceans are needed to improve climate prediction capabilities, ultimately leading to societal benefits. Inferences from the theory and model runs will aid in the interpretation of observational data sets and in the planning of future observational strategies aimed at explaining large scale flow variability. In addition to its oceanographic importance, this study will have significant implications for fundamental fluid mechanics, geophysics and climate science. During this project, one Ph.D. student at RSMAS and a postdoctoral associate at NPS will participate in the planned research activities and develop expertise in eddying ocean dynamics. In addition, two graduate (MS) Navy students will perform their thesis research at NPS on topics related to this proposal at no cost to the project.