The evolution of superharmonics excited by internal tides in non-uniform stratification

被引：22

作者：

Baker, Lois E. ^{[1
]}

Sutherland, Bruce R. ^{[2
,3
]}

机构：

[1] Imperial Coll London, Dept Civil & Environm Engn, London SW7 2AZ, England

[2] Univ Alberta, Dept Phys, Edmonton, AB T6G 2E1, Canada

[3] Univ Alberta, Dept Earth & Atmospher Sci, Edmonton, AB T6G 2E1, Canada

来源：

JOURNAL OF FLUID MECHANICS | 2020年 / 891卷

基金：

美国国家科学基金会;

关键词：

internal waves; waves in rotating fluids; HARMONIC-GENERATION;

D O I：

10.1017/jfm.2020.188

中图分类号：

O3 [力学];

学科分类号：

08 ; 0801 ;

摘要：

A weakly nonlinear time-dependent theory for the evolution of superharmonics generated by the nonlinear self-interaction of a mode-1 internal tide in non-uniform stratification is developed and compared to numerical simulations. The forcing by the internal tide is found to excite near-pure mode-1 superharmonics whose natural frequency is moderately different from twice the internal tide frequency. Consequently, the superharmonics undergo a slow periodic growth and decay that is comparable to an acoustic 'beat'. At low latitudes the beat frequency is smaller and the superharmonics can grow to larger amplitude, allowing for the possibility of a superharmonic cascade.

引用

页数：13

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