Diurnal Coastal Trapped Waves and Associated Deep‐Ocean Mixing Near the Head of Suruga Trough
Diurnal Coastal Trapped Waves and Associated Deep‐Ocean Mixing Near the Head of Suruga Trough
复制标题
骏河海槽顶部附近的昼夜沿海陷波和相关深海混合
DOI：
10.1029/2022jc018457
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Hibiya Toshiyuki
中科院分区：
文献类型：
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作者：
Nagai Taira;Hibiya Toshiyuki
预期沿海海底峡谷将成为湍流混合增强的场所，从而在沿海沃茨形成多产捕鱼区。最近的研究表明，周日的沿海被困波（CTW）在诱导显着的湍流混合在沿海海底峡谷极向30°的周日潮汐成为亚惯性的潜在作用。然而，负责在这样的海底峡谷CTW的产生和消散的详细的物理过程几乎没有调查到目前为止。在本研究中，我们进行了高分辨率（Δx，Δy= 1/240°）的非静力三维数值试验，主要集中在骏河湾位于日本骏河湾槽的北端，以研究与海底峡谷中的周日CTW相关的湍流混合过程。数值实验表明，周日（亚惯性）潮流在伊豆海岭产生CTW的气旋传播沿着骏河湾海岸。在骏河湾中部，由于昼夜CTW与粗糙的海底地形相互作用，激发了向上传播的内部背风波，从而产生了延伸到海底上方的混合热点。由此产生的全日（亚惯性）在骏河湾的潮汐能耗散被认为是远远大于与半日（超惯性）内潮。此外，它被发现，斜压能量通量的基础上一个简单的正压斜压分解严重低估了波能量通量在高CTW活动的地区。这些结果表明，CTW的存在可能是一个关键因素，以澄清在海底峡谷的耗散/混合过程。
Coastal submarine canyons are expected to be sites of enhanced turbulent mixing which create productive fishing areas in coastal waters. Recent studies suggested the potential role of diurnal coastal trapped waves (CTWs) in inducing significant turbulent mixing in coastal submarine canyons poleward of 30° where the diurnal tide becomes subinertial. Nevertheless, the detailed physical processes responsible for the generation and dissipation of CTWs in such submarine canyons have hardly been investigated so far. In the present study, to investigate the turbulent mixing processes associated with diurnal CTWs in submarine canyons, we carry out high‐resolution (Δx, Δy= 1/240°) non‐hydrostatic three‐dimensional numerical experiments focusing on Suruga Bay located at the north end of Suruga Trough, Japan. The numerical experiments show that diurnal (subinertial) tidal currents over the Izu Ridge generate CTWs which propagate cyclonically along the coast of Suruga Bay. In the middle of Suruga Bay, bottom‐intensified flow due to the diurnal CTWs interacts with rough seafloor topography to excite upward propagating internal lee waves, which create mixing hotspots extending high above the seafloor. The resulting diurnal (subinertial) tidal energy dissipation in Suruga Bay is found to be much larger than that associated with semidiurnal (superinertial) internal tides. Furthermore, it is found that baroclinic energy flux based on a simple barotropic‐baroclinic decomposition severely underestimates the wave energy flux in areas with high CTW activity. These results strongly indicate that the existence of CTWs might be a key factor to clarify the dissipation/mixing processes in submarine canyons.