Energetics of internal solitary waves in a background sheared current

Lamb, Kevin G.

doi:10.5194/npg-17-553-2010

Cited by 19 publications

(10 citation statements)

References 32 publications

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“…[], and Lien et al . [], indicating the potential of shoaling waves or the effect of spatial variations in the background current [ Lamb , ].…”

Section: Resultsmentioning

confidence: 99%

“…Since the vertical velocity w w is usually an order of magnitude smaller than the horizontal velocities, and we do not directly measure it, the horizontal kinetic energy density E hk is used to approximate E k . E hk is calculated as

E_{h k} = \frac{1}{2} ρ_{0} ({\overset{true¯}{boldU}}^{2} + {boldU}_{w}^{2} + 2 * \overset{true¯}{boldU} \times {boldU}_{w})

following Lamb [], where

{boldU}_{w}

and

\overset{true¯}{boldU}

are the horizontal wave velocity and background velocity in wave coordinates. With this formulation, the presence of a sheared background current may introduce important consequences for the evolution of the mechanical energy in the system [ Lamb , ].…”

Section: Methodsmentioning

confidence: 99%

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Characteristics, generation and mass transport of nonlinear internal waves on theWashington continental shelf

2015

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As a step toward better understanding the generation of nonlinear internal waves (NLIWs) on continental shelves and the factors determining their morphology, amplitude and propagation, we analyze more than 1500 NLIWs detected on the Washington (WA) continental shelf using four summer/fall time series of temperature and velocity measurements from a surface mooring deployed in 100 m of water. Propagating onshore toward the northeast, these NLIWs take a variety of forms, including internal solitary waves, solitary wave trains and bores. Nearly all are mode-1 depression waves that arrive semidiurnally along with the internal tide. The NLIW energy flux is correlated with the internal tide energy flux but not the local barotropic forcing, implying that the observed NLIWs arise primarily from shoaling remotely generated internal tides rather than local generation. Estimated onshore transport by the waves can equal or exceed offshore Ekman transport, suggesting the waves may play an important role in the mass balance on the continental shelf.

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“…[], and Lien et al . [], indicating the potential of shoaling waves or the effect of spatial variations in the background current [ Lamb , ].…”

Section: Resultsmentioning

confidence: 99%

E_{h k} = \frac{1}{2} ρ_{0} ({\overset{true¯}{boldU}}^{2} + {boldU}_{w}^{2} + 2 * \overset{true¯}{boldU} \times {boldU}_{w})

following Lamb [], where

{boldU}_{w}

and

\overset{true¯}{boldU}

Section: Methodsmentioning

confidence: 99%

Characteristics, generation and mass transport of nonlinear internal waves on theWashington continental shelf

2015

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“…The depth-integrated perturbation energy density flux radiating away from the front in both directions at y =−1 km (‘−' subscript) and y =1 km (‘+' subscript) is calculated as5253…”

Section: Methodsmentioning

confidence: 99%

Generation of internal solitary waves by frontally forced intrusions in geophysical flows

2016

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Internal solitary waves are hump-shaped, large-amplitude waves that are physically analogous to surface waves except that they propagate within the fluid, along density steps that typically characterize the layered vertical structure of lakes, oceans and the atmosphere. As do surface waves, internal solitary waves may overturn and break, and the process is thought to provide a globally significant source of turbulent mixing and energy dissipation. Although commonly observed in geophysical fluids, the origins of internal solitary waves remain unclear. Here we report a rarely observed natural case of the birth of internal solitary waves from a frontally forced interfacial gravity current intruding into a two-layer and vertically sheared background environment. The results of the analysis carried out suggest that fronts may represent additional and unexpected sources of internal solitary waves in regions of lakes, oceans and atmospheres that are dynamically similar to the situation examined here in the Saguenay Fjord, Canada.

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“…For ISWs of depression a background current with positive vorticity tends to decrease the limiting wave amplitude. In his study of ISW energetics in the presence of a background shear current Lamb (2010) thus employed a negative background current.…”

mentioning

confidence: 99%

The effect of strong shear on internal solitary-like waves

Stastna¹,

Coutino²,

Walter³

2021

Preprint

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Abstract. Large amplitude internal waves in the ocean propagate in a dynamic, highly variable environment with changes in background current, local depth, and stratification. The Dubreil-Jacotin-Long, or DJL, theory of exact internal solitary waves can account for a background shear, doing so at a cost of algebraic complexity and a lack of a mathematical proof of algorithm convergence. Waves in the presence of shear that is strong enough to preclude theoretical calculations have been reported in observations. We report on high resolution simulations of stratified adjustment in the presence of strong shear currents. We find instances of large amplitude solitary-like waves with recirculating cores in parameter regimes for which DJL theory fails, and of wave types that are completely different in shape from classical internal solitary waves. Both are spontaneously generated from general initial conditions. Some of the waves observed are associated with critical layers, but others exhibit a propagation speed that is very near the background current maximum. As such they are not freely propagating solitary waves, and a DJL theory would not apply. We thus provide a partial reconciliation between observations and theory.

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Energetics of internal solitary waves in a background sheared current

Cited by 19 publications

References 32 publications

Characteristics, generation and mass transport of nonlinear internal waves on theWashington continental shelf

Characteristics, generation and mass transport of nonlinear internal waves on theWashington continental shelf

Generation of internal solitary waves by frontally forced intrusions in geophysical flows

The effect of strong shear on internal solitary-like waves

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