Abstract
An internal gravity wave model was employed to simulate the generation of internal solitary waves (ISWs) over a sill by tidal flows. A westward shoaling pycnocline parameterization scheme derived from a three-parameter model was adopted, and then 14 numerical experiments were designed to investigate the influence of the pycnocline thickness, density difference across the pycnocline, westward shoaling isopycnal slope angle and pycnocline depth on the ISWs. When the pycnocline thickness on both sides of the sill increases, the total barotropic kinetic energy, total baroclinic energy and ratio of baroclinic kinetic energy (KE) to available potential energy (APE) decrease, whilst the depth of isopycnal undergoing maximum displacement and ratio of baroclinic energy to barotropic energy increase. When the density difference on both sides of the sill decreases synchronously, the total barotropic kinetic energy, ratio of baroclinic energy to barotropic energy and total baroclinic energy decrease, whilst the depth of isopycnal undergoing maximum displacement increases. When the westward shoaling isopycnal slope angle increases, the total baroclinic energy increases whilst the depth of turning point almost remains unchanged. When the depth of westward shoaling pycnocline on both sides of the sill reduces, the ratio of baroclinic energy to barotropic energy and total baroclinic energy decrease, whilst the total barotropic kinetic energy and ratio of KE to APE increase. When one of the above four different influencing factors was increased by 10% while the other factors keep unchanged, the amplitude of the leading soliton in ISW Packet A was decreased by 2.80%, 7.47%, 3.21% and 6.42% respectively. The density difference across the pycnocline and the pycnocline depth are the two most important factors in affecting the characteristics and energetics of ISWs.
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Thanks to Lamb K G for providing the IGW model.
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The Key Research Program of Frontier Sciences, Chinese Academy of Sciences (CAS) under contract No. QYZDJ-SSW-DQC034; the Talent Project from Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) under contract No. GML2019ZD0304; the National Natural Science Foundation of China (NSFC) under contract Nos 41521005 and 62071207; the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD); the Natural Science Foundation of Huai Hai Institute of Technology under contract No. Z2017006; the Project from Department of Natural Resources of Guangdong Province under contract No. (2020)017; the Open Project of State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, CAS under contract No. LTO1702; Postgraduate Research & Practice Innovation Program of Jiangsu Province under contract No. SJCX19_0963.
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Lü, H., Liu, Y., Chen, X. et al. Effects of westward shoaling pycnocline on characteristics and energetics of internal solitary wave in the Luzon Strait by numerical simulations. Acta Oceanol. Sin. 40, 20–29 (2021). https://doi.org/10.1007/s13131-021-1808-0
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DOI: https://doi.org/10.1007/s13131-021-1808-0