Generation of Internal Waves by Eddies Impinging on the Western Boundary of the North Atlantic
Generation of Internal Waves by Eddies Impinging on the Western Boundary of the North Atlantic
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DOI：
10.1175/jpo-d-14-0241.1
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发表时间：
2016-04-01
影响因子：
3.5
通讯作者：
Garabato, A. C. Naveira
中科院分区：
文献类型：
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作者：
Clement, L.;Frajka-Williams, E.;Garabato, A. C. Naveira
尽管中尺度涡旋在大尺度环流的能量再分配中发挥了重要作用，但我们对其耗散的理解仍然不完整。本文研究了北大西洋西边界衰减涡旋对内波的产生。涡旋的存在和衰减是通过高度表面相对涡量来测量的，这些相对涡量与一组全深度流计相关，这些流计延伸到距海岸约100公里的26.5°n处。此外，通过声波多普勒电流剖面仪（ADCP） 2年的高频测量，分析了地形上升上的内波，该仪器位于离岸13公里的600米深水中。尽管从测高数据中观察到的涡旋衰减具有明显的极性独立性，但与气旋（-4.7 cm s(-1)）相比，反气旋（25.2 cm s(-1)）在最深处100米的流动增强。因此，内部波场对这种与极性相关的深速度很敏感。这从涡流调制的增强耗散率中可以明显看出，该耗散率是由细尺度参数化获得的，对于大于8 cm s（-1）的近底部流动，耗散率超过10(-9)W kg（-1）。目前的研究强调了海洋西部边界对于将低模态向西传播的涡流的能量转移到高模态内波中的重要性。
Despite the major role played by mesoscale eddies in redistributing the energy of the large-scale circulation, our understanding of their dissipation is still incomplete. This study investigates the generation of internal waves by decaying eddies in the North Atlantic western boundary. The eddy presence and decay are measured from the altimetric surface relative vorticity associated with an array of full-depth current meters extending ~100 km offshore at 26.5 degrees N. In addition, internal waves are analyzed over a topographic rise from 2-yr high-frequency measurements of an acoustic Doppler current profiler (ADCP), which is located 13 km offshore in 600-m deep water. Despite an apparent polarity independence of the eddy decay observed from altimetric data, the flow in the deepest 100 m is enhanced for anticyclones (25.2 cm s(-1)) compared with cyclones (-4.7 cm s(-1)). Accordingly, the internal wave field is sensitive to this polarity-dependent deep velocity. This is apparent from the eddy-modulated enhanced dissipation rate, which is obtained from a finescale parameterization and exceeds 10(-9) W kg(-1) for near-bottom flows greater than 8 cm s(-1). The present study underlines the importance of oceanic western boundaries for removing the energy of low-mode westward-propagating eddies to higher-mode internal waves.