Structure, Energetics and Variability of the Non-Linear Internal Wave Climate Over The New Jersey Shelf

In the paper the influence of non-linear internal wave on the propagation of acoustic signal in the subsurface ocean layer containing gas bubbles is considered. During interaction with surface waves the internal wave causes its collapse and influences the structure of bubble layer. Inhomogeneous structure of the layer promotes the local speed of sound and intensity of scattering near the ocean surface to modulate by internal wave with slight shift in phase in the direction of its propagation, which agree with recent experimental observations made on the shelf of Japan Sea.

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Nonlinear internal wave packets in shelf zone

Вычислительные технологии ◽

10.25743/ict.2019.24.2.008 ◽

2019 ◽

pp. 90-98

Author(s):

Николай Иванович Макаренко ◽

Валерий Юрьевич Ляпидевский ◽

Данила Сергеевич Денисенко ◽

Дмитрий Евгеньевич Кукушкин

Keyword(s):

Internal Wave ◽

Field Experiments ◽

Fluid Layer ◽

Wave Packets ◽

Approximate Equation ◽

Periodic Wave ◽

Shelf Zone ◽

Dispersive Waves ◽

Basic Model ◽

Non Linear

В рамках модели невязкой слабостратифицированной жидкости рассматривается длинноволновое приближение, описывающее нелинейные волновые пакеты типа кноидальных волн. Построены семейства асимптотических решений, одновременно описывающие периодические последовательности приповерхностных волн в форме впадин и придонных волн типа возвышений. Показано, что картины расчетных профилей качественно согласуются со структурами внутренних волн, наблюдавшихся авторами в натурных экспериментах в шельфовой зоне моря. The problem on nonlinear internal waves propagating permanently in shallow fluid is studied semi-analytically in comparison with the field data measured on the sea shelf. At present, the most studied in this context are nonlinear solitary-type waves generated due to the tidal activity over continental slope. This paper deals with periodic cnoidaltype wave packets considered in the framework of mathematical model of continuously stratified fluid. Basic model involves the Dubreil-Jacotin-Long equation for a stream function that results from stationary fully non-linear 2D Euler equations. The longwave approximate equation describing periodic non-harmonic waves is derived by means of scaling procedure using small Boussinesq parameter. This parameter characterizes slight stratification of the fluid layer with the density profile being close to the linear stratification. The fine-scale density plays important role here because it determines the non-linearity rate of model equation, so it permits to consider strongly non-linear dispersive waves of large amplitude. As a result, constructed asymptotic solutions can simulate periodic wave-trains of sub-surface depression coupled with near-bottom wavetrains of isopycnal elevation. It is demonstrated that calculated wave profiles are in good qualitative agreement with internal wave structures observed by the authors in the field experiments performed annually during 2011-2018 in expeditions on the shelf of the Japanese sea.

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