Topographic Dynamics of the Gulf Stream

这是一个从查尔斯顿隆起到哈特拉斯角地区的地下墨西哥湾流的理论和数值研究。墨西哥湾暖流是北大西洋环流的核心要素，在海洋环流环境中已被证明是难以模拟的。这项工作将巩固目前对墨西哥湾流动力学的理解，特别是关于哈特拉斯角海岸的强劲分离，这仍然是数值模型的一个顽固问题。此外，本研究将隔离并确定哈特拉斯角附近的位置，在那里，由于地球自转的压力梯度和力之间的地转平衡，墨西哥湾流产生。从平衡流动到较小尺度的能量损失，耗散和混合，也将在这些地区被量化，这是关闭海洋能量循环的重要步骤。这些位置的确定可以为未来观测研究中涉及平衡丧失和非流体静力现象的过程的选址提供信息。除了通过期刊出版物和在国内和国际会议上发表报告等通常的传播结果的方法外，研究生还将接受多尺度计算海洋学和大、中尺度海洋动力学方面的培训。他们的博士研究将从本提案中概述的主题之一得出。此外，将与FSU女性数学、科学和工程项目（WIMSE）建立联系，招收一名本科生，从事地形数据集的开发和分析软件的开发。这将导致与本科生在主要海洋学期刊上共同发表论文。将创建一个网站来托管和维护建模结果和软件，从而使它们可供更广泛的社区使用。目标是在实验完成后的六个月内提供所有的数值数据供下载。这项研究的动机来自于最近的研究结果，强调了该地区对北大西洋环流的动力学重要性，以及关于墨西哥湾流能量学、当地地形控制和混合的开放性问题。提出的假设是：(1)墨西哥湾流与地形的相互作用促进了地下“失去平衡”，随后产生了亚中尺度现象；(2)哈特拉斯角发生的等深线辐合是墨西哥湾流与海岸分离的主要控制因素；(3)非流体静力现象，包括密度逆温，在该地区经常产生。这个项目将在墨西哥湾流的数值和理论研究范围内检验这些假设。采用的主要工具是区域嵌入式和缩小比例的数值模型，结合分析和面向过程的分析。该项目的目标是定位和描述与区域平衡损失和亚中尺度产生相关的现象，并提供墨西哥湾流对不平衡亚中尺度运动的区域能量消耗的定量估计。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This is a theoretical and numerical study of the subsurface Gulf Stream from the Charleston Bump to the Cape Hatteras region. The Gulf Stream is a central element of the North Atlantic circulation that has proven subtle to model in ocean general circulation settings. This work will solidify current understanding of Gulf Stream dynamics, particularly with regards to the robust separation from the coast at Cape Hatteras which remains a stubborn problem for numerical models. In addition, this study will isolate and define the locations in the vicinity of Cape Hatteras where the Gulf Stream comes out of geostrophic balance between the pressure gradients and forces due to the rotation of the Earth. The loss of energy from balanced flows to smaller scales, dissipation, and mixing, will also be quantified in these areas, an important step to closing the oceanic energy cycle. The identification of these locations can inform site selection for future observational studies of processes involved in loss of balance and non-hydrostatic phenomena. In addition to the usual methods for disseminating results by means of journal publications and presentations at national and international meetings, a graduate student will be trained in multi-scale computational oceanography and large and mesoscale ocean dynamics. Their Ph.D. research will be drawn from one of the topics outlined in this proposal. Also, a connection with the FSU Women in Mathematics, Science and Engineering (WIMSE) program will be engaged to recruit an undergraduate to work on the development of topographic datasets, and the development of analysis software. This will result in publications joint with the undergraduate in major oceanographic journals. A website will be created to host and maintain the modeling results and software, thereby making them available to the broader community for their use. The goal is to have all the numerical data available for download within six months of completing the experiments.The motivations for the study come from recent results emphasizing the dynamical importance of this region to the North Atlantic general circulation and open questions about Gulf Stream energetics, local topographic controls and mixing. The presented hypotheses are: (1) Gulf Stream -topography interaction promotes subsurface ''loss of balance'' and subsequently the generation of submesoscale phenomena, (2) the isobath convergence occurring at Cape Hatteras is a major control on Gulf Stream separation from the coast and (3) non-hydrostatic phenomena, including density inversions, are routinely generated in this area. This project will examine these hypotheses within the confines of a numerical and theoretical study of the Gulf Stream. The primary tools to be employed are regional embedded and downscaled numerical models, combined with analytical and process-oriented analyses. The goals of the project are to locate and describe the phenomena associated with regional loss of balance and submesoscale generation and provide quantitative estimates of the regional energy drain from the Gulf Stream to unbalanced, submesoscale motions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.