A Directional Decomposition Method to Estimate the Reflection and Transmission of Nonlinear Internal Waves Over a Slope

Gong, Yunhui; Xie, Jieshuo; Xu, Jiexin; Chen, Zhiwu; He, Yinghui; Cai, Shuqun

doi:10.1029/2022jc018598

Cited by 2 publications

(4 citation statements)

References 48 publications

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“…We also employed the Directional Fourier Filter (DFF) method [42,43] to decompose the altimetric signals induced by internal tides propagating in different directions. This method is suitable for grid-based data, and has been proved to be effective for the MIOST-IT dataset in the SCS [23].…”

Section: Directional Fourier Filter Methodsmentioning

confidence: 99%

Semidiurnal Internal Tide Interference in the Northern South China Sea

Wang,

Li,

Huang

2024

JMSE

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Multiwave interference plays a crucial role in shaping the spatial variations of internal tides. Based on a combination of in situ mooring and altimeter data, interference of semidiurnal internal tides was investigated in the northern South China Sea. Mooring observations indicate the observed kinetic-to-potential energy ratio and group speed are both relatively lower than the theoretical values of mode-1 semidiurnal internal tides, indicating the presence of partly-standing waves. This is consistent with the altimeter result that the mooring was located at the antinode within the interference pattern formed by the superposition of the westward and southward semidiurnal internal tides from the Luzon Strait and the continental slope of the southern Taiwan Strait. However, the kinetic-to-potential energy ratio and group velocity were notably changed when an anticyclonic eddy passed by the mooring. By employing the ray-tracing method, we identified that mesoscale processes may induce a phase difference in the semidiurnal internal tides between the Luzon Strait and the continental slope of the southern Taiwan Strait. This alteration further leads to changes in the positions of nodes and antinodes within the interference pattern of the semidiurnal internal tides.

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Section: Directional Fourier Filter Methodsmentioning

confidence: 99%

Semidiurnal Internal Tide Interference in the Northern South China Sea

Wang,

Li,

Huang

2024

JMSE

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“…To quantify the IT energy flux reaching and leaving the USWC margin, we directionally decompose the complex IT signals near the USWC with a Discrete Fourier Transform (DFT) technique (Gong et al., 2021, 2022; Mercier et al., 2008; Siyanbola et al., 2023). The depth‐integrated IT energy flux can be expressed as

\mathbf{F}=\underset{{\mathbf{F}}_{\text{on}}}{\underbrace{\int \nolimits_{-H}^{0}\langle {p}_{\text{on}}^{\prime }{\mathbf{u}}_{\text{on}}^{\prime }\mathrm{d}z\rangle }}+\underset{{\mathbf{F}}_{\text{off}}}{\underbrace{\int \nolimits_{-H}^{0}\langle {p}_{\text{off}}^{\prime }{\mathbf{u}}_{\text{off}}^{\prime }\mathrm{d}z\rangle }}+\underset{{\mathbf{F}}_{\mathrm{x}}}{\underbrace{\int \nolimits_{-H}^{0}\langle {p}_{\text{off}}^{\prime }{\mathbf{u}}_{\text{on}}^{\prime }\mathrm{d}z\rangle +\int \nolimits_{-H}^{0}\langle {p}_{\text{on}}^{\prime }{\mathbf{u}}_{\text{off}}^{\prime }\mathrm{d}z\rangle }},

where F on , F off , and F x are the time‐mean onshore (eastward), offshore (westward) propagating, and the cross‐term energy fluxes, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…To quantify the IT energy flux reaching and leaving the USWC margin, we directionally decompose the complex IT signals near the USWC with a Discrete Fourier Transform (DFT) technique (Gong et al, 2021(Gong et al, , 2022Mercier et al, 2008;Siyanbola et al, 2023). The depth-integrated IT energy flux can be expressed as…”

Section: It Energy Flux Directional Decompositionmentioning

confidence: 99%

“…Prompted by an observation of a middepth pycnocline on the West Shetland slope, Hall et al (2013) assessed the impacts of a cross-shore varying criticality on the reflectivity and transmissivity of incident IWs using a two-dimensional numerical model. The fate of incident IWs at the continental margins have also been studied using realistic three-dimensional numerical simulations but at regional scales (e.g., Gong et al, 2022;Kelly et al, 2012;Klymak et al, 2016;Masunaga et al, 2023;Osborne et al, 2011;S. Wang et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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Interactions of Remotely Generated Internal Tides With the U.S. West Coast Continental Margin

Siyanbola,

Buijsman,

Delpech

et al. 2024

JGR Oceans

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Through interactions with the continental margins, incident low‐mode internal tides (ITs) can be reflected, scattered to high modes, transmitted onto the shelf and dissipated. We investigate the fate of remotely generated mode‐1 ITs in the U.S. West Coast (USWC) continental margin using two 4‐km horizontal resolution regional simulations. These 1‐year long simulations have realistic stratification, and atmospheric, tidal, and sub‐tidal forcings. In addition, one of these simulations has remote internal wave (IW) forcing at the open boundaries while the other does not. To compute the IT reflectivity of the USWC margin, we separate the IT energy fluxes into onshore and offshore propagating components using a Discrete Fourier Transform in space and time. Overall, ∼20% of the remote mode‐1 semidiurnal IT energy fluxes reflect off the USWC margin, 40% is scattered to modes 2–5, and 7% is transmitted onto the shelf while the remaining is dissipated on the continental slope. Furthermore, our results reveal that differences in stratification, slope criticality, topographic roughness and angle of incidence cause these fractions to vary spatially and temporally along the USWC margin. However, there is no clear seasonal variability in these estimates. Remote IWs enhance the advection and diffusion of heat in the continental margin, resulting in cooling at the surface and warming at depth, and a reduction in the thermocline stratification. These results suggest that low‐mode ITs can cause water mass transformation in continental margins that are far away from their generation sites.

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A Directional Decomposition Method to Estimate the Reflection and Transmission of Nonlinear Internal Waves Over a Slope

Cited by 2 publications

References 48 publications

Semidiurnal Internal Tide Interference in the Northern South China Sea

Semidiurnal Internal Tide Interference in the Northern South China Sea

Interactions of Remotely Generated Internal Tides With the U.S. West Coast Continental Margin

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