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Dynamics of intrathermocline vortices in a gyre flow over a seamount chain

机译：海山链上回旋流中高温曲线内旋涡的动力学

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The interaction of meddies with a complex distribution of seamounts is studied in a three-layer quasi-geostrophic model on the f-plane. This study aims at understanding if and how this seamount chain can represent a barrier to the propagation of these eddies and how it can be involved in their decay. The eddies are idealized as vortex patches in the middle layer, interacting with a regional cyclonic current and with ten idealized seamounts. The numerical code is based on the contour surgery technique. The initial position, radius, shape, number and polarity of the eddies are varied. The main results are the following: (1) Though they do not describe the unsteady flow, the streamlines of the regional and topographic flow provide a useful estimate of the vortex trajectories, in particular towards the major seamounts, where stronger velocity shears are expected. (2) The tallest and widest seamounts which have the largest vorticity reservoir are able to considerably erode the vortices, but also to draw anticyclones towards the seamount top. The ability of narrower seamounts to erode vortices is related to their multiplicity. (3) Only 1/3 of the anticyclones with about 30-km radius reach the southern boundary of the seamount chain, and their erosion is larger than 50 %. The other anticyclones are either completely eroded or trapped over a wide seamount top. Cyclones are less affected by seamounts because they oppose the topographic draft towards the seamount top and they drift along the side of the seamount. (4) Large vortices resist topographic erosion more efficiently. The rate of erosion grows from a few percent to about 35–50 % as the vortex radius decreases from about 60 to 30 km. Small cyclones are not eroded, contrary to small anticyclones (which completely decay), in relation with the different trajectories of these eddies in the vicinity of the seamounts. (5) The detailed vortex shape does not appear critical for their evolution, if they are close enough to the seamount chain initially. The interaction between a group of vortices initially north of the seamount chain can modify their trajectory to such an extent that they finally avoid collision with seamounts. (6) Finally, meddy trajectories across the Horseshoe Seamounts (data from the AMUSE experiment) show qualitative similarity with the vortex paths in the model. Several events of vortex decay also occur at comparable locations (in particular over the wide and tall seamounts) in the model and observations.
机译：在f平面上的三层拟地转模型中研究了具有复杂海山分布的药物相互作用。这项研究旨在了解该海山链是否以及如何代表这些旋涡的传播障碍，以及如何参与其旋涡的衰减。涡流在中层被理想化为涡旋斑块，与区域性气旋流和十个理想化海山相互作用。数值代码基于轮廓手术技术。涡流的初始位置，半径，形状，数量和极性是变化的。主要结果如下：（1）尽管没有描述非恒定流，但区域和地形流的流线提供了涡旋轨迹的有用估计，特别是对主要海山的涡流轨迹，预计在这些海山中速度剪切力会更大。 （2）拥有最大旋涡储层的最高和最宽的海山能够大大侵蚀旋涡，但也能向海山顶部吸引反气旋。较窄的海山侵蚀涡旋的能力与其多样性有关。 （3）只有1/3半径约30公里的反气旋到达海山链的南边界，其侵蚀大于50％。其他反气旋被完全侵蚀或被困在宽阔的海山顶上。旋风不受海山的影响，因为它们与地形吃水相对，朝向海山顶部，并且它们沿着海山的侧面漂移。 （4）大涡旋能更有效地抵抗地形侵蚀。随着涡流半径从大约60 km减小到30 km，侵蚀率从百分之几增加到大约35–50％。相对于小型旋风分离器（其完全衰减）而言，小型旋风分离器不会受到侵蚀，因为相对于海山附近这些涡流的不同轨迹。 （5）详细的涡旋形状对于它们的演化似乎并不关键，只要它们最初与海山链足够近。最初在海山链以北的一组涡流之间的相互作用可以改变其轨迹，以至于它们最终避免与海山碰撞。 （6）最后，横跨马蹄海山的混合运动轨迹（来自AMUSE实验的数据）与模型中的涡旋路径在质量上相似。涡旋衰减的一些事件也发生在模型和观测值的可比较位置（尤其是在宽阔的海山上）。

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