Eddy Mean Flow Interactions in the Kuroshio Extension

本研究的动机是黑潮延伸系统研究（KESS），它提供了一个前所未有的一套独特的适合于研究射流，其涡度变化，以及它们之间的相互作用的观测。研究的目标是从KESS和支持观测中描述黑潮延伸区（KE）中的涡-平均流相互作用，研究WBC喷流延伸系统相关的理想化配置中的涡-平均流相互作用，最后测试从这些理想化研究中得出的理论认识与海洋系统的相关性。这项工作将导致新的见解的一种机制，通过这种机制，从本地化的强迫涡可以驱动与KE和墨西哥湾流中观察到的深回流速度一致的强度的再循环环流，以及支持与这些射流系统的再循环的假设，至少部分地，涡驱动。此外，新的见解将获得到什么可能决定的平均射流及其再循环的属性，因为它们演变下游的非线性动力学的结果。与海洋的大多数其他区域相比，WBC喷流平均路径上的涡动能量要大几个数量级，我们预计涡动变化将在这些系统的动力学中发挥重要作用。沿着WBC喷流的平均路径。KESS数据集提供了一个独特的机会，以扩展我们目前对这一作用的性质和重要性的理解，特别是使我们能够了解有关不稳定射流中涡流平均流相互作用的理论如何适用于实际海洋。这项研究的一个预期结果是提高了对支配WBC射流侧面的再循环环流的强度和结构的过程的理解。再循环环流从根本上改变了动力学结构的射流，并大大增加了这些电流的净运输。它们也是重要的亚热带模态水形成的场所。这项工作将测试的假设，这些回流区是涡驱动的，并寻求确定正压和斜压不稳定性在这个过程中的相对重要性，从这项工作的结果承诺提高理解WBC射流，在这些系统中的涡平均流相互作用可能是至关重要的整体动态。白细胞是全球热量传输的重要组成部分之一，因此在调节全球气候方面也是如此。因此，在这里学到的经验教训将有重要的应用，以评估气候研究所需的现实的海洋环流模式，并在KE地区的最终实现气候多变性研究目标的一个有效的监测战略的设计。这项工作可能对海洋建模有影响。它可能会导致在这些系统中解决各种涡流过程的影响和重要性的更好的理解。所寻求的动力学机制的见解可能会建议合适的参数化未解决的涡流的影响。

ABSTRACTThis study was motivated by the Kuroshio Extension System Study (KESS), which provides an unprecedented suite of observations uniquely suited to study the jet, its eddy variability, and their interactions. The goals of the study are to characterize eddy-mean flow interactions in the Kuroshio Extension (KE) from the KESS and supporting observations, to examine eddy-mean flow interactions in idealized configurations relevant to WBC jet extension systems, and finally to test the relevance of the theoretical understanding derived from these idealized studies to the oceanic system. This work WILL result in new insights into a mechanism by which eddies from a localized forcing can drive recirculation gyres of a strength consistent with the deep recirculation velocities observed in the KE and Gulf Stream, as well as support for the hypothesis that the recirculation associated with these jet systems are, at least partially, eddy-driven. In addition, new insights will be gained into what may determine the properties of the mean jet and its recirculation as they evolve downstream as a consequence of the nonlinear dynamics. Eddy energies are orders of magnitude larger along the mean paths of WBC jets compared to most other regions of the ocean and we expect eddy variability to play an important role in the dynamics of these systems. The KESS data set provides a unique opportunity to extend our present understanding of the nature and importance of this role, in particular, allowing us to understand how theories about eddy-mean flow interaction in unstable jets apply to the actual ocean. One anticipated result of this research is improved understanding of the processes that govern the strength and structure of the recirculation gyres that flank WBC jets. Recirculation gyres fundamentally alter the dynamical structure of the jet and add significantly to the net transport of these currents. They also are important as the sites of subtropical mode water formation. This work will test the hypothesis that these recirculation zones are eddy-driven and seek to determine the relative importance of barotropic and baroclinic instability in this process.Results from this work promise an improved understanding of WBC jets, as eddy-mean flow interactions in these systems are likely critical to their overall dynamics. WBCs are one of the foremost components in global heat transport and thus in regulating the global climate. As such, the lessons learned here will have important application to the evaluation of realistic ocean general circulation models required for climate studies, and also to the design of an efficient and effective monitoring strategy in the KE region for eventual achievement of CLIVAR goals. This work likely has implications for ocean modeling. It may lead to an improved understanding of the impact and importance of having various eddy processes resolved in these systems. The insights into the dynamical mechanisms that are sought may suggest suitable parameterizations for the effects of unresolved eddies.