Generation of Internal Lee Waves by Lateral Circulation in a Coastal Plain Estuary
Generation of Internal Lee Waves by Lateral Circulation in a Coastal Plain Estuary
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DOI：
10.1175/jpo-d-18-0142.1
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发表时间：
2019-06
影响因子：
3.5
通讯作者：
Xiaohui Xie;Ming Li
中科院分区：
文献类型：
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作者：
Xiaohui Xie;Ming Li
最近在切萨皮克湾（Chesapeake Bay）的跨渠道部分进行的系泊观测表明，内部孤立波在潮汐周期的某些阶段经常出现，并从深通道传播到浅浅滩。假设这些波是由侧流电流在通道 - 波形地形上产生的内部Lee波的非线性陡峭引起的。在这项研究中，进行了数值建模，以研究横向循环和跨通道地形之间的相互作用，并辨别内部李波的发电机理。在潮汐潮汐期间，横向底部的Ekman强迫逆时针驱动（研究河口）的横向循环，强电流在深通道的西侧上流过地分层水，并产生大型的同志位移。当横向流相对于模式2的内波变得超临界时，在深通道的侧面产生了模式2内部Lee波，然后随后传播到西浅滩上。当相对于模式1的内波，底部的侧向流变得几乎至关重要或超临界时，Lee波就会演变为内部液压跳跃。在浅浅滩上，Lee波或跳跃演变成高度的内部孔。
Recent mooring observations at a cross-channel section in Chesapeake Bay showed that internal solitary waves regularly appeared during certain phases of a tidal cycle and propagated from the deep channel to the shallow shoal. It was hypothesized that these waves resulted from the nonlinear steepening of internal lee waves generated by lateral currents over channel-shoal topography. In this study numerical modeling is conducted to investigate the interaction between lateral circulation and cross-channel topography and discern the generation mechanism of the internal lee waves. During ebb tides, lateral bottom Ekman forcing drives a counterclockwise (looking into estuary) lateral circulation, with strong currents advecting stratified water over the western flank of the deep channel and producing large isopycnal displacements. When the lateral flow becomes supercritical with respect to mode-2 internal waves, a mode-2 internal lee wave is generated on the flank of the deep channel and subsequently propagates onto the western shoal. When the bottom lateral flow becomes near-critical or supercritical with respect to mode-1 internal waves, the lee wave evolves into an internal hydraulic jump. On the shallow shoal, the lee waves or jumps evolve into internal bores of elevation.