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首页> 外文期刊>Journal of Physical Oceanography >Submesoscale Dynamics of a Gulf Stream Frontal Eddy in the South Atlantic Bight
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Submesoscale Dynamics of a Gulf Stream Frontal Eddy in the South Atlantic Bight

机译：南大西洋海岸线上湾流额涡的亚中尺度动力学

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Frontal eddies are commonly observed and understood as the product of an instability of the Gulf Stream along the southeastern U.S. seaboard. Here, the authors study the dynamics of a simulated Gulf Stream frontal eddy in the South Atlantic Bight, including its structure, propagation, and emergent submesoscale interior and neighboring substructure, at very high resolution (dx = 150 m). A rich submesoscale structure is revealed inside the frontal eddy. Meander-induced frontogenesis sharpens the gradients and forms very sharp fronts between the eddy and the adjacent Gulf Stream. The strong straining increases the velocity shear and suppresses the development of barotropic instability on the upstream face of the meander trough. Barotropic instability of the sheared flow develops from small-amplitude perturbations when the straining weakens at the trough. Small-scale meandering perturbations evolve into rolled-up submesoscale vortices that are advected back into the interior of the frontal eddy. The deep fronts mix the tracer properties and enhance vertical exchanges of tracers between the mixed layer and the interior, as diagnosed by virtual Lagrangian particles. The frontal eddy also locally creates a strong southward flow against the shelf leading to topographic generation of submesoscale centrifugal instability and mixing. In eddy-resolving models that do not resolve these submesoscale processes, there is a significant weakening of the intensity of the upwelling in the core of the frontal eddies, and their decay is generally too fast.
机译：正面涡流通常被观察到并被理解为美国东南沿海沿湾流不稳定的产物。在这里，作者研究了在南大西洋海岸线上模拟的墨西哥湾流正面涡旋的动力学，包括高分辨率，高分辨力（dx = 150 m）的结构，传播以及新兴的亚中尺度内部和邻近子结构。额涡内部揭示出丰富的亚中尺度结构。弯曲引起的前生使梯度变陡并且在涡流和相邻的墨西哥湾流之间形成非常尖锐的锋面。强应变增加了速度剪切，并抑制了曲流槽上游面上正压不稳定的发展。当槽中的应变减弱时，剪切流的正压失稳是由小振幅扰动引起的。小规模的蜿蜒扰动演变成卷状的亚中尺度涡流，这些涡流平移回额涡内部。通过虚拟拉格朗日粒子的诊断，深层前沿混合了示踪剂的特性，并增强了示踪剂在混合层和内部之间的垂直交换。正面的涡流还在局部对着陆架产生强烈的向南流动，导致地形产生了亚中尺度的离心失稳和混合。在不能解决这些亚中尺度过程的涡旋解析模型中，额流涡旋核心的上升流强度明显减弱，并且它们的衰减通常太快。

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