Numerical Experiments on the Breaking of Solitary Internal Wavesover a Slope–Shelf Topography

Vlasenko, Vasiliy; Hutter, Kolumban

doi:10.1175/1520-0485(2002)032<1779:neotbo>2.0.co;2

Cited by 227 publications

(199 citation statements)

References 49 publications

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“…It is now about 3 km long, spanning depths of 130-140 m. The slope of the wave front is less than it was at t = 42 h and in the centre of the wave the thermocline is almost parallel to the bottom (between 65.5 and 67.5 km). This is a well-know feature of shoaling waves when the thermocline is close to the bottom (Vlasenko and Hutter, 2002;Orr and Mignerey, 2003;Lamb and Nguyen, 2009). The rear of the wave is much steeper and behind the leading depression the thermocline has been raised above its equilibrium position (x = 66 km).…”

Section: Resultsmentioning

confidence: 86%

“…Helfrich and Melville (1986) and Helfrich (1992) considered the breaking criteria for a two-layered system. Vlasenko and Hutter (2002) performed simulations, in a continuously stratified fluid, of breaking solitary waves on slope-shelf topography and determined a parametrisation for the location of wave breaking for stratifications and bathymetry based on observations in the Andaman and Sulu seas.…”

Section: K G Lamb and A Warn-varnas: Shoaling Internal Solitary Wavesmentioning

confidence: 99%

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Two-dimensional numerical simulations of shoaling internal solitary waves at the ASIAEX site in the South China Sea

Lamb

Warn-Varnas

2015

Nonlin. Processes Geophys.

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Abstract. The interaction of barotropic tides with LuzonStrait topography generates some of the world's largest internal solitary waves which eventually shoal and dissipate on the western side of the northern South China Sea. Twodimensional numerical simulations of the shoaling of a single internal solitary wave at the site of the Asian Seas International Acoustic Experiment (ASIAEX) have been undertaken in order to investigate the sensitivity of the shoaling process to the stratification and the underlying bathymetry and to explore the influence of rotation. The bulk of the simulations are inviscid; however, exploratory simulations using a vertical eddy-viscosity confined to a near bottom layer, along with a no-slip boundary condition, suggest that viscous effects may become important in water shallower than about 200 m. A shoaling solitary wave fissions into several waves. At depths of 200-300 m the front of the leading waves become nearly parallel to the bottom and develop a very steep back as has been observed. The leading waves are followed by waves of elevation (pedestals) that are conjugate to the waves of depression ahead and behind them. Horizontal resolutions of at least 50 m are required to simulate these well. Wave breaking was found to occur behind the second or third of the leading solitary waves, never at the back of the leading wave. Comparisons of the shoaling of waves started at depths of 1000 and 3000 m show significant differences and the shoaling waves can be significantly non-adiabatic even at depths greater than 2000 m. When waves reach a depth of 200 m, their amplitudes can be more than 50 % larger than the largest possible solitary wave at that depth. The shoaling behaviour is sensitive to the presence of small-scale features in the bathymetry: a 200 m high bump at 700 m depth can result in the generation of many mode-two waves and of higher mode waves. Sensitivity to the stratification is considered by using three stratifications based on summer observations. They primarily differ in the depth of the thermocline. The generation of mode-two waves and the behaviour of the waves in shallow water is sensitive to this depth. Rotation affects the shoaling waves by reducing the amplitude of the leading waves via the radiation of long trailing inertiagravity waves. The nonlinear-dispersive evolution of these inertia-gravity waves results in the formation of secondary mode-one wave packets.

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Section: Resultsmentioning

confidence: 86%

Section: K G Lamb and A Warn-varnas: Shoaling Internal Solitary Wavesmentioning

confidence: 99%

Two-dimensional numerical simulations of shoaling internal solitary waves at the ASIAEX site in the South China Sea

Lamb

Warn-Varnas

2015

Nonlin. Processes Geophys.

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“…This paper will consider observational results from a single linear mooring line approximately normal to the continental shelf break and will not attempt to address the two-dimensional results. Ultimately, the wave energy must be dissipated on the Chinese continental shelf via friction, refraction, wave breaking, and radial spreading [27], [35], [37]. These processes are better described by the ASIAEX Low-Cost (LOCO) Moorings located further onshore and are the focus of other ASIAEX papers [2], [4].…”

Section: E Internal Wavesmentioning

confidence: 99%

“…This is because the soliton peaks were pushed up by the shoaling bottom and became broader also, since the soliton width is inversely proportional to its vertical displacement. An explanation of the wave widening and deformation in terms of linear wave speed changes for a thermocline transition from near-surface to near-bottom depth can be found in the literature [37], [44]. Essentially, the nonlinear processes no longer counteract the varying linear wave speed computed throughout the wave to allow a wave of permanent form, and the trough and shoulders of the wave diverge as the bathymetry shoals.…”

Section: Wave Transformation In Shallow Watermentioning

confidence: 99%

Internal Solitons in the Northeastern South China Sea Part I: Sources and Deep Water Propagation

Ramp

Tang²,

Duda³

et al. 2004

IEEE J. Oceanic Eng.

340

321

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Abstract-A moored array of current, temperature, conductivity, and pressure sensors was deployed across the Chinese continental shelf and slope in support of the Asian Seas International Acoustics Experiment. The goal of the observations was to quantify the water column variability in order to understand the along-and across-shore low-frequency acoustic propagation in shallow water. The moorings were deployed from April 21-May 19, 2001 and sampled at 1-5 min intervals to capture the full range of temporal variability without aliasing the internal wave field. The dominant oceanographic signal by far was in fact the highly nonlinear internal waves (or solitons) which were generated near the Batan Islands in the Luzon Strait and propagated 485 km across deep water to the observation region. Dubbed trans-basin waves, to distinguish them from other, smaller nonlinear waves generated locally near the shelf break, these waves had amplitudes ranging from 29 to greater than 140 m and were among the largest such waves ever observed in the world's oceans. The waves arrived at the most offshore mooring in two clusters lasting 7-8 days each separated by five days when no waves were observed. Within each cluster, two types of waves arrived which have been named type-a and type-b. The type-a waves had greater amplitude than the type-b waves and arrived with remarkable regularity at the same time each day, 24 h apart. The type-b waves were weaker than the type-a waves, arrived an hour later each day, and generally consisted of a single soliton growing out of the center of the wave packet. Comparison with modeled barotropic tides from the generation region revealed that: 1) The two clusters were generated around the time of the spring tides in the Luzon strait; and 2) The type-a waves were generated on the strong side of the diurnal inequality while the type-b waves were generated on the weaker beat. The position of the Kuroshio intrusion into the Luzon Strait may modulate the strength of the waves being produced. As the waves shoaled, the huge lead solitons first split into two solitons then merged together into a broad region of thermocline depression at depths less than 120 m. Elevation waves sprang up behind them as they continued to propagate onshore. The elevation waves also grew out of regions where the locally-generated internal tide forced the main thermocline down near the bottom. The "critical T. Y. Tang is with the Institute of Oceanography, National Taiwan University, Taipei, ROC.H. point" where the upper and lower layers were equal was a good indicator of when the depression or elevation waves would form, however this was not a static point, but rather varied in both space and time according to the presence or absence of the internal tides and the incoming trans-basin waves themselves.

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“…In our case, there are two elevation waves created behind the original depression wave (Figure 1). The ISW evolution in this phase has been studied by numerical method several times [Knickerbocker and Newell, 1980;Liu et al, 1998;Vlasenko and Hutter, 2002].…”

Section: Conversion Processmentioning

confidence: 99%

Satellite observation of internal solitary waves converting polarity

Zhao

Klemas

Zheng

et al. 2003

Geophysical Research Letters

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[1] On a SPOT-3 visible image over the South China Sea continental shelf, two contrasting signatures of internal solitary waves (ISWs) are observed: darker stripes leading brighter stripes in the lower part, and brighter stripes leading darker stripes in the upper part. The authors suggest that the contrasting patterns are caused by ISWs of different polarities. A packet of ISWs is observed in the process of converting polarity due to bottom shoaling, both in the propagation direction and in the transect direction. The evolution process can be obtained by transferring information from the spatial domain to the temporal domain. The conversion process starts with the original depression ISWs passing the 160 m isobath. The evolution process can be divided into two phases: the first is the broadening of the original depression waves and the second is the appearance of the new-born elevation waves. These two phases are verified using numerical simulation.

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Numerical Experiments on the Breaking of Solitary Internal Wavesover a Slope–Shelf Topography

Cited by 227 publications

References 49 publications

Two-dimensional numerical simulations of shoaling internal solitary waves at the ASIAEX site in the South China Sea

Two-dimensional numerical simulations of shoaling internal solitary waves at the ASIAEX site in the South China Sea

Internal Solitons in the Northeastern South China Sea Part I: Sources and Deep Water Propagation

Satellite observation of internal solitary waves converting polarity

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