INTERACTION OF VORTICES WITH TOPOGRAPHY

涡流与地形的相互作用

• 批准号: EP/G031835/1
• 负责人: Roger Grimshaw
• 金额: $ 2万
• 依托单位: Loughborough University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FG031835%2F1
• 关键词: INTERACTION; VORTICES; TOPOGRAPHY

Irregular topography is a prevalent ocean feature, appearing in the shape of the ocean bottom, along the coastline, and on the shelves and slopes that connect the coast to the deep abyss. Strong jet-like currents, with considerable variability and enhanced mixing, are often observed near topography, implying that the continental shelves and slopes, ridges and seamounts exert a strong dynamical oceanic influence. Past studies have illustrated the complicated nature of vortex-topography interaction in which smaller-scale vortices are often produced; thatis, topography catalyzes a forward cascade in the mesoscale fields and may provide important routes to dissipation.The interaction of an ocean vortex with the continental shelf and slope is one aspect of a more general problem about wave-vortex interactions in a variable medium. A crucial parameter here is the ratio of the shelf width to the vortex size, which is typically small. In order to develop adequate mathematical models, and to clarify the basic physical mechanisms, we propose a thorough investigation of the evolution of a strong vortex in the vicinity of confined shelf-like topography. The first stage, when the vortex approaches the shelf from the open ocean, will be analyzed theoretically to determine the coastally-trapped waves forced by an approaching eddy. Since a proper description of ocean dynamics over a steep continental slope adjacent to the deep-water side of a shelf-break requires baroclinic effects to be taken into account, we propose using a two-layer model in the deep area matched with a barotropic model in the shallow area, where the ocean depth is smaller than the interface depth. Such a combination of a barotropic-baroclinic model should capture the most essential elements of current variability in the littoral zone, which remain presently relatively unexplored.At the next stage, the on-shelf advection of shelf water with high potential vorticity into the open ocean results in the development of a vortex sheet around the intense eddy. The subsequent rolling-up into smaller-scale cyclonic vortices will be studied numerically using a certain equation set which captures the essential dynamical processes. The results of the analysis will be compared with numerical simulations and observational data for a range of the relevant parameters. Our general aim is to construct a mathematical model for the process of vortex-shelf interaction, which can provide an adequate description of variability and mixing near confined topography.

不规则的地形是一个普遍的海洋特征，表现为海底的形状、沿着海岸线以及连接海岸和深渊的大陆架和斜坡。在地形附近经常观察到类似急流的强海流，其变异性很大，混合作用增强，这意味着大陆架和大陆坡、海脊和海山对海洋动力有很强的影响。过去的研究表明，涡地形相互作用的复杂性，其中小尺度的涡往往会产生，即地形催化在中尺度领域的前向级联，并可能提供重要的途径dispersion.The相互作用的海洋涡与大陆架和斜坡是一个更普遍的问题，在一个可变的介质中的波涡相互作用的一个方面。这里的一个关键参数是搁板宽度与涡流大小的比率，该比率通常很小。为了发展适当的数学模型，并澄清基本的物理机制，我们提出了一个深入的调查，在附近的封闭的货架状地形的强涡的演变。第一阶段，当涡流从开阔的海洋接近大陆架时，将进行理论分析，以确定由接近的涡流所强迫的海岸捕获波。由于适当的描述海洋动力学在一个陡峭的大陆坡附近的深水一侧的陆架坡折需要斜压效应考虑在内，我们建议使用一个两层模式在深海区匹配正压模式在浅水区，海洋深度小于界面深度。正压-斜压模式的这种组合应能捕捉到沿岸的区海流变率的最基本要素，而这些要素目前相对来说尚未被探索。在下一个阶段，具有高位涡的陆架水在陆架上平流进入开阔海洋，导致在强涡流周围形成涡面。随后卷起成较小尺度的气旋涡旋将使用一定的方程组，捕捉基本的动力学过程进行数值研究。分析结果将与一系列相关参数的数值模拟和观测数据进行比较。我们的总体目标是建立一个涡架相互作用过程的数学模型，它可以提供一个足够的描述的变化和混合附近的封闭地形。