Horizontal structure and excitation of primary motions in a strongly stratified lake
Horizontal structure and excitation of primary motions in a strongly stratified lake
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强分层湖泊的水平结构和初级运动激发
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
M. Kumagai
中科院分区：
文献类型：
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作者：
K. Shimizu;J. Imberger;M. Kumagai
将水平面中的模态分析扩展到具有不规则水深的分层盆地，并将该理论应用于琵琶湖，以研究盆地尺度内波和涡旋的水平结构和激发。盆地尺度内波的水平结构由气旋和反气旋椭圆胞组成，每个椭圆胞似乎都遵循椭圆盆地中开尔文波和庞加莱波的色散关系。内波的优先激发取决于细胞的排列和风向，但风应力旋度的空间分布在湖面上主要决定了随后的环流的水平结构。解耦的各个模式的演化方程提供了一个很好的近似激发的内部波和早期阶段的激励的回旋前的非线性效应和阻尼变得显着。水动力模拟结果的模态分解也表明，风的主要作用是激发内波;然而，这些内波在几天内被阻尼，平静期间的动力学由涡旋主导，说明内波对混合和涡旋对长期水平输送的重要性。
A modal analysis in the horizontal plane was extended to a layer‐stratified basin with irregular bathymetry, and the theory was applied to Lake Biwa to investigate the horizontal structure and excitation of the basin‐scale internal waves and gyres. The horizontal structure of the basin‐scale internal waves consisted of cyclonic and anticyclonic elliptic cells, each of which appeared to follow the dispersion relationship of Kelvin and PoincarÉ waves in elliptic basins. The internal waves were preferentially excited depending on the arrangement of the cells and the wind direction, but the spatial distribution of wind stress curl over the lake primarily determined the horizontal structure of the ensuing gyres. Decoupled evolutionary equations for the individual modes provided a good approximation for excitation of the internal waves and early stages of excitation of the gyres before nonlinear effects and damping become significant. The modal decomposition of hydrodynamic simulation results also showed that the primary action of the wind was to excite the internal waves; however, these internal waves were damped within a few days, and the dynamics during calm periods were dominated by the gyres, illustrating the importance of internal waves on mixing and gyres on long‐term horizontal transport.