Oblique wave-wave interactions of nonlinear near-surface internal waves in the Strait of Georgia

2012 ◽  
Vol 117 (C6) ◽  
pp. n/a-n/a ◽  
Author(s):  
C. Wang ◽  
R. Pawlowicz
Keyword(s):  
Internal Waves ◽  
Wave Interactions ◽  
Near Surface ◽  
Strait Of Georgia ◽  
Oblique Wave

scholarly journals The energy of near‐surface internal waves in the strait of Georgia

Atmosphere ◽  
1977 ◽  
Vol 15 (3) ◽  
pp. 151-159 ◽  
Author(s):  
G. Samuels ◽  
P.H. LeBlond
Keyword(s):  
Internal Waves ◽  
Near Surface ◽  
Strait Of Georgia

scholarly journals Energy transformations and dissipation of nonlinear internal waves over New Jersey's continental shelf

2010 ◽  
Vol 17 (4) ◽  
pp. 345-360 ◽  
Author(s):  
E. L. Shroyer ◽  
J. N. Moum ◽  
J. D. Nash
Keyword(s):  
Continental Shelf ◽  
Internal Waves ◽  
Turbulent Mixing ◽  
Internal Tide ◽  
Flux Divergence ◽  
Wave Interactions ◽  
Nonlinear Internal Waves ◽  
Dissipative Loss ◽  
Peak Energy

Abstract. The energetics of large amplitude, high-frequency nonlinear internal waves (NLIWs) observed over the New Jersey continental shelf are summarized from ship and mooring data acquired in August 2006. NLIW energy was typically on the order of 105 Jm−1, and the wave dissipative loss was near 50 W m−1. However, wave energies (dissipations) were ~10 (~2) times greater than these values during a particular week-long period. In general, the leading waves in a packet grew in energy across the outer shelf, reached peak values near 40 km inshore of the shelf break, and then lost energy to turbulent mixing. Wave growth was attributed to the bore-like nature of the internal tide, as wave groups that exhibited larger long-term (lasting for a few hours) displacements of the pycnocline offshore typically had greater energy inshore. For ship-observed NLIWs, the average dissipative loss over the region of decay scaled with the peak energy in waves; extending this scaling to mooring data produces estimates of NLIW dissipative loss consistent with those made using the flux divergence of wave energy. The decay time scale of the NLIWs was approximately 12 h corresponding to a length scale of 35 km (O(100) wavelengths). Imposed on these larger scale energetic trends, were short, rapid exchanges associated with wave interactions and shoaling on a localized topographic rise. Both of these events resulted in the onset of shear instabilities and large energy loss to turbulent mixing.

A laboratory study of stratified accelerating shear flow over a rough boundary

1984 ◽  
Vol 138 ◽  
pp. 185-196 ◽  
Author(s):  
S. A. Thorpe
Keyword(s):  
Shear Flow ◽  
Internal Waves ◽  
Mixing Layer ◽  
Internal Gravity Waves ◽  
Rough Boundary ◽  
Turbulent Layer ◽  
Near Surface ◽  
Rate Of Spread ◽  
Vertical Scale ◽  
The Waves

Experiments are made in which a stratified shear flow, accelerating from rest and containing a level where the direction of flow reverses, is generated over a rough floor. The roughness elements consist of parallel square bars set at regular intervals normal to the direction of flow. Radiating internal gravity waves are generated in the early stages of flow, whilst flow separation behind the bars produces turbulent mixing regions which eventually amalgamate and entirely cover the floor. This turbulent layer spreads vertically less rapidly than the internal waves. Observed features of the waves are compared with those predicted by a model in which the floor is assumed to be sinusoidal, and fair agreement is found for the amplitude, phase and vertical wavenumber of the waves, even when the latter becomes large.The rate of spread of the turbulent layer depends on the separation of the bars. Some interaction between the turbulence and the internal waves occurs near the edge of the turbulent layer. Wave-breaking is prevalent and the vertical scale of the waves is affected by turbulent eddies. The radiating internal waves are suppressed by replacing the bars by an array of square cubes, but there is continued evidence of features resembling internal waves near the boundary of the turbulent region. Structures are observed which bear some similarities to those found at the foot of the near-surface mixing layer in a lake.

Longshore Current Generation by Internal Waves in the Strait of Georgia

1975 ◽  
Vol 12 (3) ◽  
pp. 472-488 ◽  
Author(s):  
Richard E. Thomson
Keyword(s):  
Internal Waves ◽  
Maximum Speed ◽  
Longshore Current ◽  
Delta Area ◽  
Strait Of Georgia ◽  
Wave Characteristics ◽  
Fraser River Delta ◽  
Vertical Eddy ◽  
Measured Water ◽  
A Current

Presented in this paper is a derivation of the longshore current generated by breaking lowest mode internal waves in a two layer fluid of slowly shallowing depth, with emphasis on the nearshore region of the Fraser River delta in the Strait of Georgia. It is proposed that such a current, having a maximum speed of order 104/μv cm3/s2 (equal to 102 cm/s for reasonable vertical eddy viscosities, μv, of 102 cm2/s) and a width of order kilometers based on measured water properties and internal wave characteristics in the Strait, is responsible for the persistent northward flow observed to be associated with the delta in summer. Accordingly, it is suggested that the longshore current would have important implications to sedimentation rates and pollutant dispersal in the delta area, with greatest effects possibly occurring in summer and fall when the stratification in the Strait of Georgia is most pronounced.

A numerical investigation of solitary internal waves with trapped cores formed via shoaling

2002 ◽  
Vol 451 ◽  
pp. 109-144 ◽  
Author(s):  
KEVIN G. LAMB
Keyword(s):  
Internal Waves ◽  
Mixed Layer ◽  
Propagation Speed ◽  
Horizontal Velocity ◽  
Buoyancy Frequency ◽  
Surface Mixed Layer ◽  
Near Surface ◽  
Flow Limit ◽  
Wave Propagation Speed ◽  
Solitary Internal Waves

The formation of solitary internal waves with trapped cores via shoaling is investigated numerically. For density fields for which the buoyancy frequency increases monotonically towards the surface, sufficiently large solitary waves break as they shoal and form solitary-like waves with trapped fluid cores. Properties of large-amplitude waves are shown to be sensitive to the near-surface stratification. For the monotonic stratifications considered, waves with open streamlines are limited in amplitude by the breaking limit (maximum horizontal velocity equals wave propagation speed). When an exponential density stratification is modified to include a thin surface mixed layer, wave amplitudes are limited by the conjugate flow limit, in which case waves become long and horizontally uniform in the centre. The maximum horizontal velocity in the limiting wave is much less than the wave's propagation speed and as a consequence, waves with trapped cores are not formed in the presence of the surface mixed layer.

Numerical study of internal wave–wave interactions in a stratified fluid

2000 ◽  
Vol 415 ◽  
pp. 65-87 ◽  
Author(s):  
A. JAVAM ◽  
J. IMBERGER ◽  
S. W. ARMFIELD
Keyword(s):  
Internal Wave ◽  
Internal Waves ◽  
Numerical Study ◽  
Experimental Studies ◽  
Interaction Mechanism ◽  
Stratified Fluid ◽  
Interaction Region ◽  
Staggered Grid ◽  
Open Boundary ◽  
Wave Interactions

A finite volume method is used to study the generation, propagation and interaction of internal waves in a linearly stratified fluid. The internal waves were generated using single and multiple momentum sources. The full unsteady equations of motion were solved using a SIMPLE scheme on a non-staggered grid. An open boundary, based on the Sommerfield radiation condition, allowed waves to propagate through the computational boundaries with minimum reflection and distortion. For the case of a single momentum source, the effects of viscosity and nonlinearity on the generation and propagation of internal waves were investigated.Internal wave–wave interactions between two wave rays were studied using two momentum sources. The rays generated travelled out from the sources and intersected in interaction regions where nonlinear interactions caused the waves to break. When two rays had identical properties but opposite horizontal phase velocities (symmetric interaction), the interactions were not described by a triad interaction mechanism. Instead, energy was transferred to smaller wavelengths and, a few periods later, to standing evanescent modes in multiples of the primary frequency (greater than the ambient buoyancy frequencies) in the interaction region. The accumulation of the energy caused by these trapped modes within the interaction region resulted in the overturning of the density field. When the two rays had different properties (apart from the multiples of the forcing frequencies) the divisions of the forcing frequencies as well as the combination of the different frequencies were observed within the interaction region.The model was validated by comparing the results with those from experimental studies. Further, the energy balance was conserved and the dissipation of energy was shown to be related to the degree of nonlinear interaction.

scholarly journals Characteristics of Mach effect induced by oblique wave-wave interactions of internal solitary waves in ocean

2016 ◽  
Vol 61 (4-5) ◽  
pp. 529-535
Author(s):  
MengMeng GU ◽  
XinLong WANG ◽  
Hui DU ◽  
Gang WEI ◽  
CaiXia WANG
Keyword(s):  
Solitary Waves ◽  
Internal Solitary Waves ◽  
Wave Interactions ◽  
Oblique Wave

scholarly journals Subsurface Jets in the Northwestern Gulf of Mexico

2009 ◽  
Vol 39 (11) ◽  
pp. 2875-2891 ◽  
Author(s):  
Peter Hamilton ◽  
Antoine Badan
Keyword(s):  
Velocity Profile ◽  
Gulf Of Mexico ◽  
Internal Waves ◽  
Vertical Axis ◽  
Surface Currents ◽  
Profile Data ◽  
Near Surface ◽  
Anomalous Density ◽  
Slope Topography ◽  
Upper Slope

Abstract Subsurface jets, defined as having velocity maxima >40 cm s−1 at depths between 100 and 350 m, and being surrounded by much weaker near-surface currents, have been observed over the northwestern Gulf of Mexico continental slope. The observations were from an array of 14 moorings equipped with upward-looking 75-kHz ADCPs deployed at 450–500 m. A total of 10 jet events were observed in 18 ADCP years of velocity profile data, where these events were clearly not the result of downward-propagating inertial internal waves. The jets had durations from about 1 to 8 days and were usually associated with interactions between similarly sized cyclones and anticyclones over the slope or with the interaction of an eddy with upper-slope topography. The jets are associated with potential vorticity anomalies and their inferred length scales indicate that the dynamics depart from simple geostrophic balances. Observed anomalous density gradients present during the jets seem to involve the tilting of the vertical axis of the center of rotation of one or more of the interacting eddies.

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