Energy balance and momentum budgets due to the internal tides generated by a group of submarine canyon
Energy balance and momentum budgets due to the internal tides generated by a group of submarine canyon
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一组海底峡谷产生的内潮汐的能量平衡和动量预算
DOI：
10.1016/j.ocemod.2022.102126
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发表时间：
2022
期刊：
影响因子：
3.2
通讯作者：
Xu Jingping
中科院分区：
文献类型：
--
作者：
Li Qiang;Wang Bing;Xu Jingping
一项现场多波束勘测在南海北部大陆架上发现了一组间隔规则的海底峡谷。然而，它们不包含在海洋学界常用的测深数据集中。在本研究中，我们采用超高分辨率（精细至 54 m）数值模型来解析这些海底峡谷，以研究它们对当地内潮产生和传播的影响。结果表明，正压潮汐向内潮汐转换率在海底峡谷两侧呈现交替分布。潮汐流的旋转方向决定了西侧的正转换率和东侧的负转换率。海底峡谷造成的粗糙海底并没有明显改变正压潮的消散，但显着影响内潮的消散，导致平均消散率为1.2× 10− 9 W kg− 1。内潮还引起底部增强的平均流，导致大陆坡上的西向平均输送和每个海底峡谷内的顺时针环流。平均流量满足科里奥利力、压力梯度以及正压潮和内潮的动量通量散度之间的动量预算。我们强调，内潮汐伪动量通量的发散起到了应力的作用，并且在海底和海面附近尤其得到加强。它对海面的影响甚至可以与中风（∼ 13 ms−1）相媲美。
A field multibeam survey discovered a group of regularly-spaced submarine canyons on the continental shelf in the northern South China Sea. However, they are not included in the bathymetry datasets commonly used by the oceanographic community. In this study, we employ a very-high-resolution (as fine as 54 m) numerical model that resolves these submarine canyons to investigate their impacts on the local internal tide generation and propagation. Results show that the barotropic to internal tidal conversion rate exhibits an alternating distribution on each flank of submarine canyons. Rotational direction of the tidal flow determines a positive conversion rate on the west flank and a negative rate on the east flank. The rough seafloor due to the submarine canyons does not appreciably change the dissipation of barotropic tides, but significantly affects the dissipation of internal tides, leading to an averaged dissipation rate of 1.2× 10− 9 W kg− 1. Internal tides also induce a bottom intensified mean flow, which causes westward mean transport on the continental slope and a clockwise circulation inside each submarine canyon. The mean flow satisfies a momentum budget between the Coriolis force, pressure gradient and divergence of momentum flux of barotropic and internal tides. We highlight that the divergence of the pseudo-momentum flux of internal tides acts as a stress and is especially reinforced near the sea bottom and surface. Its effect on the sea surface is even comparable with moderate winds (∼ 13 ms− 1).