Eddy Mean Flow Interactions in the Kuroshio Extension

黑潮延伸区的涡流平均流相互作用

• 批准号: 0825550
• 负责人: Steven Jayne
• 金额: $ 6.12万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0825550&HistoricalAwards=false
• 关键词: Eddy; Mean; Flow; Interactions; Kuroshio

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.

这项研究是由黑潮延伸系统研究(KESS)推动的，KESS提供了一套史无前例的观测，特别适合于研究急流、其涡旋可变性及其相互作用。这项研究的目的是从KESS和辅助观测中描述黑潮延伸(KE)中的涡流-平均流相互作用，检查与WBC喷流延伸系统相关的理想化构型中的涡流-平均流相互作用，最后检验这些理想化研究得出的理论理解与海洋系统的相关性。这项工作将对局部化强迫的涡能驱动再循环涡旋的机制产生新的见解，其强度与在KE和墨西哥湾流中观察到的深再循环速度一致，并支持与这些急流系统相关的再循环至少部分由涡流驱动的假设。此外，我们还将对由于非线性动力学而向下游演化的平均喷流及其再循环的性质可能起决定作用的因素有新的认识。与海洋的大多数其他区域相比，沿WBC喷流平均路径的涡旋能量要大几个数量级，我们预计涡旋变化将在这些系统的动力学中发挥重要作用。KESS数据集提供了一个独特的机会来扩展我们目前对这一作用的性质和重要性的理解，特别是使我们能够理解关于不稳定喷流中的涡流-平均流相互作用的理论如何应用于实际的海洋。这项研究的一个预期结果是改善了对控制WBC喷气式飞机侧翼再循环涡旋的强度和结构的过程的理解。环流涡旋从根本上改变了喷流的动力结构，并显著增加了这些水流的净输送。它们也是副热带模式水形成的重要场所。这项工作将检验这些回流区是由涡旋驱动的假设，并试图确定正压和斜压不稳定在这一过程中的相对重要性。这项工作的结果有助于更好地理解WBC急流，因为这些系统中的涡流-平均流相互作用可能对它们的整体动力学至关重要。WBC是全球热量输送的重要组成部分之一，因此也是调节全球气候的重要组成部分。因此，这里吸取的经验教训将对评估气候研究所需的现实海洋环流模式，以及为最终实现CLIVAR目标而在KE地区设计有效的监测战略具有重要的应用价值。这项工作可能会对海洋建模产生影响。这可能会使人们更好地理解在这些系统中解决各种涡旋过程的影响和重要性。对所寻求的动力学机制的洞察可能会为未解决的旋涡的影响提供合适的参数。