Generation and evolution of mode-two internal waves in the South China Sea

Liu, Antony K.; Su, Feng-Chun; Hsu, Meng−Kai; Kuo, Nan-Jung; Ho, Chung-Ru

doi:10.1016/j.csr.2013.02.009

Cited by 47 publications

(61 citation statements)

References 16 publications

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“…For example, Helfrich and Melville (1986), Vlasenko and Alpers (2005), and Liu et al (2013) suggested that mode-2 ISWs can emerge after mode-1 ISWs pass over a continental slope or a ridge. Stastna and Peltier (2005) found that mode-2 ISWs could be generated by resonant interaction of a depth-independent velocity field with topography, for example, by the interaction of the barotropic tide with a ridge (Vlasenko and Alpers 2005;Xie et al 2010;Ramp et al 2012).…”

Section: B Backgroundmentioning

confidence: 97%

Multimodal Internal Waves Generated over a Subcritical Ridge: Impact of the Upper-Ocean Stratification

Xie

Pan

Jay

2015

Journal of Physical Oceanography

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Interaction of barotropic tides with subsurface topography is vital to ocean mixing. Yet the behavior of largeamplitude, nonlinear, internal solitary waves (ISWs) that can cause strong mixing remains poorly understood, especially that of higher-mode and multimodal internal waves. Therefore, a 2.5-dimensional, nonhydrostatic model with adjustable vertical resolution was developed to investigate effects of upper-ocean stratification on tidally induced multimodal internal waves and to show how they are generated by the subcritical ridge where only upward-propagating internal wave beams (IWBs) are present. The effects of the stratification on properties and characteristics of the excited IWBs and on the energy partition of the radiated mode-1 and mode-2 internal waves were investigated based on the model results. Higher modes of internal waves can also be effectively generated in the IWBs by the subcritical topography, and the contribution to IWBs from higher modes increases with the upper-ocean stratification. Mode-2 ISWs can be excited from the IWBs if both the tidal Froude number Fr 0 2 5 U 0 /c 2 and the contribution to IWBs from mode-2 waves are sufficiently high (U 0 is the tidal current speed, and c 2 is the phase speed of mode-2 waves). In a moderately stratified upper ocean, both mode-1 and mode-2 ISWs can be produced, but for weak (strong) stratification, only mode-1 (mode-2) ISWs are generated. Further, it is found that the distance between two successive mode-1 or mode-2 ISW trains increases linearly with the upper-ocean stratification. The ratio of the kinetic energy to the available potential energy for the mode-2 ISWs increases with the upper-ocean stratification in a strongly stratified ocean.

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Section: B Backgroundmentioning

confidence: 97%

Multimodal Internal Waves Generated over a Subcritical Ridge: Impact of the Upper-Ocean Stratification

Xie

Pan

Jay

2015

Journal of Physical Oceanography

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“…This process apparently is consistent with the SCS observation cases [16] that mode-2 IWs usually followed mode-1 IWs in summer. Liu et al [17] pointed out that when background environment changes at the shelf break, like density, shear as well as depth, the incident mode-1 waves may radiate out and disintegrate into higher modes Figure 4(a) clearly shows that the temperature of Section A is less than that of Section B (about 1 degree Celsius), and Section B is likely to be on the closed isotherm of 25 degrees Celsius. And close isotherm is a feature of eddy.…”

Section: Generation Mechanism Of Mode-2 Iwmentioning

confidence: 95%

SAR imaging of mode-2 internal waves in the South China Sea

Yang

Dong

2015

2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

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Mode 2 internal wave (IW) signatures are observed by the RADARSAT-1 synthetic aperture radar (SAR) in the Northeast South China Sea on April 07, 2001. In this study, we prove that the conditions of the study area are favorable for the generation and propagation of mode-2 waves to appear in SAR imagery. The generation mechanism of this mode 2 IW is mode-1 IW evolves into mode-2 convex IW packets when shoaling.

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“…The background environmental coefficients of the KdV-type equations were also used to illustrate the mode-2 ISWs observed by both in situ and satellite observations (Dong et al, 2016;Yang et al, 2009), and it is shown that the variability of background stratification and/or current increases the relative importance of wave nonlinearity to wave dispersion of mode-2 waves and thus favors the evolution of mode-2 ISWs. Theoretical analysis and numerical simulations are also performed to investigate the generation (Lamb & Warn-Varnas, 2015;Liu et al, 2013;Xie, Pan, et al, 2015) or shoaling dynamics (Guo & Chen, 2012) of mode-2 ISWs in the northern SCS. Using a modal decomposition theory from deep water to shallow water, Liu et al (2013) propose that the generation of mode-2 ISWs on the shelf region is due to the disintegration of shoaling mode-1 solitons from the deep ocean, a mechanism similar to that proposed by Helfrich and Melville (1986).…”

Section: Introductionmentioning

confidence: 99%

“…Theoretical analysis and numerical simulations are also performed to investigate the generation (Lamb & Warn-Varnas, 2015;Liu et al, 2013;Xie, Pan, et al, 2015) or shoaling dynamics (Guo & Chen, 2012) of mode-2 ISWs in the northern SCS. Using a modal decomposition theory from deep water to shallow water, Liu et al (2013) propose that the generation of mode-2 ISWs on the shelf region is due to the disintegration of shoaling mode-1 solitons from the deep ocean, a mechanism similar to that proposed by Helfrich and Melville (1986). Lamb and Warn-Varnas (2015) show that the interaction of a shoaling mode-1 ISW with a 200-m-high bump at~700 m over the continental slope can result in the generation of many mode-2 internal waves.…”

Section: Introductionmentioning

confidence: 99%

Bumpy Topographic Effects on the Transbasin Evolution of Large‐Amplitude Internal Solitary Wave in the Northern South China Sea

Xie

Cai

2019

JGR Oceans

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The bumpy continental slope/shelf topography is a quite common feature in the northern South China Sea (SCS), yet its effect on the shoaling internal solitary waves (ISWs) remains poorly understood. Therefore, numerical simulations by a fully nonlinear, nonhydrostatic model are carried out to explore the bumpy continental slope/shelf topographic effects on the transbasin evolution of large‐amplitude ISW in the northern SCS. It is found that the prominent bumps over both continental slope and shelf regions play significant roles in modulating the evolution of transbasin ISW in the northern SCS. The bump over the continental slope is capable of triggering a solitary‐like mode‐2 internal wave packet, while the bump over the continental shelf can result in three wave groups, including a leading group of rank‐ordered mode‐1 ISW packet and two following groups of non‐rank‐ordered mode‐1 ISW packet and mode‐2 internal waves. The bumps can cause a peak‐to‐peak difference of the energy decay rate of ISW up to 10–20 kW/m over continental slope region and 3–5 kW/m over continental shelf region. The wave kinetic energy (KE) is found to exceed the available potential energy (APE) by as much as 50% over the continental shelf break region. Over the shelf region, however, the bumps can first make the KE drop to as low as only 80% of the APE, but later the KE might bounce back to approximately 1.1–1.2 times of the APE. Both onshore‐ and offshore‐propagating beam‐like disturbances are found to be excited by the bumps. Except for the onshore‐propagating mode‐2 ISW packet, the reflected offshore‐propagating waves in different internal modes are also formed. These onshore‐ and offshore‐propagating multimodal internal waves can be clarified by the beam scattering and local generation mechanism.

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Generation and evolution of mode-two internal waves in the South China Sea

Cited by 47 publications

References 16 publications

Multimodal Internal Waves Generated over a Subcritical Ridge: Impact of the Upper-Ocean Stratification

Multimodal Internal Waves Generated over a Subcritical Ridge: Impact of the Upper-Ocean Stratification

SAR imaging of mode-2 internal waves in the South China Sea

Bumpy Topographic Effects on the Transbasin Evolution of Large‐Amplitude Internal Solitary Wave in the Northern South China Sea

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