Observations of nonlinear internal waves on the outer New England continental shelf during the summer Shelfbreak Primer study

Colosi, John A.; Beardsley, Robert C.; Lynch, James F.; Gawarkiewicz, Glen; Chiu, Ching Sang; Scotti, Alberto

doi:10.1029/2000jc900124

Cited by 114 publications

(101 citation statements)

References 17 publications

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“…The large elapsed time between the first two waves was typical of all the a-waves and indicates significant dispersion, suggesting the waves traveled a great distance. This time is much greater than that of previously observed waves on continental shelves where it is typically only 15-20 min for waves generated close by [24], [46]. For the Sulu Sea it was typically about 40-50 min for waves that had been traveling for two days across the sea [26].…”

Section: F Modal Structure Of Wave Packetsmentioning

confidence: 67%

“…The waves over the New England shelf, e.g., [23], [24] are similar to the ECS shelf break waves but even smaller and weaker. Soliton amplitudes were order 10 m in 70 m depth in the SWARM region [23] and 15-30 in the Shelfbreak PRIMER experiment [24].…”

Section: Comparison With Other Locationsmentioning

confidence: 92%

“…Soliton amplitudes were order 10 m in 70 m depth in the SWARM region [23] and 15-30 in the Shelfbreak PRIMER experiment [24]. Typical periods in both experiments were order 15 min or less indicating local generation processes.…”

Section: Comparison With Other Locationsmentioning

confidence: 92%

“…As will be seen, the generation region for the waves (the Luzon Strait) can be deduced from the ASIAEX observations, but save for the satellite remote sensing, there were no observations conducted there. There are many instances in the literature associating the generation of strong nonlinear internal waves with sills, straits, and abrupt topography, for instance in the Mediterranean [17], [18] fjord-like structures [18], [19] and at continental shelf breaks [21]- [24]. Generation is most often attributed in some way to tidal flow across abrupt topography [19], [20], [25]- [27] and the ASIAEX waves would appear to fit this description.…”

Section: E Internal Wavesmentioning

confidence: 99%

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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

328

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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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Section: F Modal Structure Of Wave Packetsmentioning

confidence: 67%

Section: Comparison With Other Locationsmentioning

confidence: 92%

Section: Comparison With Other Locationsmentioning

confidence: 92%

Section: E Internal Wavesmentioning

confidence: 99%

See 2 more Smart Citations

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

328

View full text Add to dashboard Cite

show abstract

“…The present oceanographic feature of interest that provides the spatial distribution of sound speed indicated in Eq. (1) is the ISW, which has been represented by the Korteweg-de Vries (KdV) equation in previous studies (Liu, 1988;Preisig and Duda, 1997;Colosi et al, 2001;Shroyer et al, 2011). Preisig and Duda (1997) expressed the shallow water ISW displacement of the boundary in the hyperbolic secant form…”

Section: Extended Criterion For Adiabatic Invariancementioning

confidence: 99%

Enhanced acoustic mode coupling resulting from an internal solitary wave approaching the shelfbreak in the South China Sea

Chiu

Reeder

Chang

et al. 2013

The Journal of the Acoustical Society of America

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Internal waves and bathymetric variation create time-and space-dependent alterations in the ocean acoustic waveguide, and cause subsequent coupling of acoustic energy between propagating normal modes. In this paper, the criterion for adiabatic invariance is extended to the case of an internal solitary wave (ISW) encountering a sloping bathymetry (i.e., continental shelfbreak). Predictions based on the extended criterion for adiabatic invariance are compared to experimental observations from the Asian Seas International Acoustics Experiment. Using a mode 1 starter field, results demonstrate time-dependent coupling of mode 1 energy to higher adjacent modes, followed by abrupt coupling of mode 5-7 energy to nonadjacent modes 8-20, produces enhanced mode coupling and higher received levels downrange of the oceanographic and bathymetric features. Numerical simulations demonstrate that increasing ISW amplitude and seafloor slope enhance the coupling of energy to adjacent and nonadjacent modes. This enhanced coupling is the direct result of the simultaneous influence of the ISW and its proximity to the shelfbreak, and, compared to the individual effect of the ISW or shelfbreak, has the capacity to scatter 2-4 times the amount of acoustic energy from below the thermocline into the upper water column beyond the shelfbreak in realistic environments.

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Connecting wind‐driven upwelling and offshore stratification to nearshore internal bores and oxygen variability

et al. 2014

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This study utilizes field observations in southern Monterey Bay, CA, to examine how regionalscale upwelling and changing offshore (shelf) conditions influence nearshore internal bores. We show that the low-frequency wind forcing (e.g., upwelling/relaxation time scales) modifies the offshore stratification and thermocline depth. This in turn alters the strength and structure of observed internal bores in the nearshore. An internal bore strength index is defined using the high-pass filtered potential energy density anomaly in the nearshore. During weak upwelling favorable conditions and wind relaxations, the offshore thermocline deepens. In this case, both the amplitude of the offshore internal tide and the strength of the nearshore internal bores increase. In contrast, during strong upwelling conditions, the offshore thermocline shoals toward the surface, resulting in a decrease in the offshore internal tide amplitude. As a result, cold water accumulates in the nearshore (nearshore pooling), and the internal bore strength index decreases. Empirical orthogonal functions are utilized to support the claim that the bore events contribute to the majority of the variance in cross-shelf exchange and transport in the nearshore. Observed individual bores can drive shock-like drops in dissolved oxygen (DO) with rapid onset times, while extended upwelling periods with reduced bore activity produce longer duration, low DO events.

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Observations of nonlinear internal waves on the outer New England continental shelf during the summer Shelfbreak Primer study

Cited by 114 publications

References 17 publications

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

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

Enhanced acoustic mode coupling resulting from an internal solitary wave approaching the shelfbreak in the South China Sea

Connecting wind‐driven upwelling and offshore stratification to nearshore internal bores and oxygen variability

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