Global Dynamics Approach to Gap Leaping and Loop Current Systems

环流，如墨西哥湾或南中国海的环流，是海洋环流的重要组成部分。它们连接着沿海和公海，通过输送营养物质、物种和热量影响区域气候和生态系统，通过输送污染物和影响飓风强度对人口产生更直接的影响。众所周知，环流主导着墨西哥湾上层1公里环流，可能是深层环流的主要驱动因素。尽管它很重要，但人们对真实海洋环境中环流的动力学知之甚少。实验室实验和理想化的数值（由PI和他的合作者进行）最近证实了回路电流系统中存在多个稳态和迟滞，并提供了一个框架，在这个框架下，这些复杂的动力学可以被理解。也就是说，环电流系统的全局动力学似乎是由解的尖突变几何控制的。本工作的目的是在实验和理论上将跳隙边界流的Cusp公式扩展到更现实的海洋情景，从而使这种全球动力系统的理解能够更广泛地应用于实际的海洋系统。这将通过旋转台实验室实验和理论考虑的结合来完成。这项研究的结果将更好地为决策者提供有关气候变化和其他环境压力因素对半封闭盆地的影响的信息。多态假设（尖点突变框架）在现实海洋条件下的证实和系统推广将影响广泛的领域。在墨西哥湾，如果环流模型正确，飓风强度可以更准确地预测。它也将提供一种手段？把海洋教育带到内陆？至少有一名研究生和一名本科生直接参与这个项目，但更广泛地说，它将有助于建立一个内陆海洋教育中心，从而使大部分未被代表的人口接触到海洋科学。该项目还将协助初级教师PI的专业发展，并将成果的传播提供一种独特的基本地球物理流体动力学相互作用方法。尖点突变观点源于对环流的动力系统解释（在这种情况下代表了墨西哥湾环流的全球动力系统方法）。研究表明，当惯性控制参数（流强度）和涡度约束（物理上与海平面、风强迫、分层和地形有关）发生变化时，环流系统会发生全球分岔。通过在突变面上跟踪Loop Current状态，可以以一种逻辑和可预测的方式理解循环状态、非循环状态和周期性涡流脱落状态之间的转换。尖端灾难代表了一种完全不同的思考环路电流动力学的方式。传统的环流研究主要集中在对锋涡形成和传播、正斜压不稳定发展以及其他局部动力学特征的量化和识别上。尖端突变公式表明，这些局部动力学仅仅是全球系统分岔的症状。这一理论的一个重要结论是，半封闭盆地可能对微妙的气候变化表现出极端的敏感性。应该指出的是，尖端突变是由整个海洋系统普遍存在的惯性和涡度约束之间的平衡引起的，这表明本研究的结果是广泛适用的。

Loop currents, such as those in the Gulf of Mexico or South China Sea, represent an important part of the ocean circulation. Linking the coastal and open ocean, they affect regional climate and ecosystems through the transport of nutrients, species and heat, with more direct influence on human population through the transport of pollutants and influence on hurricane intensity. It is well known that the Loop Current dominates the upper 1km of circulation in the Gulf of Mexico and is likely a major driver of the deep circulation. Despite its importance, little is understood about the dynamics of loop currents in real ocean situations. Laboratory experiments and idealized numerics (conducted by PI and his collaborators) have recently confirmed the existence of multiple steady states and hysteresis in loop current systems, as well as provided a framework under which these complex dynamics might be understood. That is, the global dynamics of loop current systems appear to be governed by a cusp catastrophe geometry of solutions. The objective of this work is to experimentally and theoretically expand the Cusp formulation of gap-leaping boundary currents toward more realistic oceanographic scenarios, so that such global dynamical systems understanding can be more broadly applied to actual oceanographic systems. This will be accomplished through a combination of rotating table laboratory experiments and theoretical considerations. The results of this research will better inform decision makers about the effects of climate change and other environmental stressors on semi-enclosed basins. The confirmation and systematic extension of the multiple states hypothesis (cusp catastrophe framework) in realistic ocean conditions will impact a wide range of fields. In the Gulf of Mexico, hurricane intensity may be predicted more accurately if loop currents are modeled correctly. It will also provide a means for ?bringing ocean education inland? with at least one graduate student and one undergraduate student participating directly in this project, but more generally it will help establish an inland hub for oceanographic education, thus exposing a largely unrepresented population to ocean science. The project will also serve to assist in the professional development of junior faculty PI, and the dissemination of results will present a unique approach to fundamental geophysical fluid dynamic interaction.The cusp catastrophe perspective follows from a dynamical systems interpretation of the Loop Current (which in this case represents a global dynamical systems approach to Gulf of Mexico circulation). It has been shown that when the control parameters of inertia (current strength) and vorticity constraints (which physically relate to sea level, wind forcing, stratification and topography) are varied, the loop current systems undergoes global bifurcations. By tracing the Loop Current state on the catastrophe surface, transitions between a looping state, a non-looping state and a periodic eddy shedding state can be understood in a logical and predictable way. The cusp catastrophe represents a fundamentally different way of thinking about Loop Current dynamics. Traditional studies of the Loop Current have focused on quantification/identification of frontal eddy formation and propagation, barotropic and baroclinic instability development, and other local dynamical features. The cusp catastrophe formulation suggests that these local dynamics are merely symptoms of a global system bifurcation. An important consequence of this theory is that semi-enclosed basins are likely to exhibit extreme sensitivity to subtle climate shifting. It should be noted that the cusp catastrophe follows from a balance between inertia and vorticity constraints which are prevalent throughout the entire ocean system, suggesting the results of this study are broadly applicable.