Internal wave energetics modulated by Indonesian Throughflow at Lombok Strait

2020 ◽  
Author(s):  
Zhenhua Xu
Keyword(s):  
Solitary Waves ◽  
Southern Oscillation ◽  
Internal Tide ◽  
Internal Tides ◽  
Internal Solitary Waves ◽  
Indonesian Throughflow ◽  
Indonesian Seas ◽  
The North ◽  
Tide Propagation ◽  
Seasonal And Interannual Variations

<p>The interaction between the energetic internal waves in the Indonesian Seas and the Indonesian Throughflow (ITF) is not well known. Here we conduct a series of high-resolution numerical simulations surrounding the Lombok Strait, Indonesia, which is an important exit channel for the ITF, to explore the influences of the ITF on the spatiotemporal variations of M2 internal tides and associated internal solitary waves from the Strait. The ITF enhances the north-south asymmetry of internal tide propagation from the Lombok Strait, thus resulting in the spatial variability of northward and southward internal solitary waves. Interannual variability of internal tide generation and dissipation are due to ITF and air-sea freshwaterflux induced stratification variations associated with El Niño-Southern Oscillation. The local dissipation efficiency q exhibits substantial seasonal and interannual variations, which may provide effective feedback to the climate processes in the low-latitude equatorial oceans.</p>

scholarly journals Internal Solitary Waves in the Brazilian SE Continental Shelf: Observations by Synthetic Aperture Radar

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
João A. Lorenzzetti ◽  
Fabian G. Dias
Keyword(s):  
Continental Shelf ◽  
Solitary Waves ◽  
Internal Tide ◽  
Shelf Break ◽  
Internal Tides ◽  
Internal Solitary Waves ◽  
Envisat Asar ◽  
Current Variation ◽  
Seasonal Signal ◽  
Observation Period

We present an analysis of internal solitary waves (ISWs) on the SE Brazilian continental shelf using a set of Envisat/ASAR satellite images. For the 17-month observation period, 467 ISW packets were detected. Most of observed solitons were associated to 4–6 ms-1 wind. The number of ISW packets shows a seasonal signal with a peak in summer, with higher concentration in the outer shelf in all seasons, followed by midshelf during the summer. Propagation direction of ISWs was predominantly onshore with packets separated by typical M2 internal tide wavelengths (~10–40 km). The highest values of the barotropic tidal forcing F are concentrated at the shelf break between 200 and 500 m isobaths. These characteristics suggest that ISWs are formed from nonlinear disintegration of internal tides generated at the shelf break that propagate shoreward as interfacial internal waves. No significant change in the number of ISWs from spring to neap tides was observed in spite of significant tidal current variation (60%). Even not being a region of strong tides, this study shows that ISWs are a frequent and widespread feature, possibly playing a significant dynamic role, affecting biological production, sediment dispersion, and transport.

Internal-Wave-Driven Mixing: Global Geography and Budgets

2017 ◽  
Vol 47 (6) ◽  
pp. 1325-1345 ◽  
Author(s):  
Eric Kunze
Keyword(s):  
Internal Wave ◽  
Internal Tide ◽  
Internal Tides ◽  
Tidal Mixing ◽  
Linear Wave ◽  
Power Sources ◽  
The North ◽  
Dissipation Rates ◽  
Thickness Variability ◽  
Significant Pathway

AbstractInternal-wave-driven dissipation rates ε and diapycnal diffusivities K are inferred globally using a finescale parameterization based on vertical strain applied to ~30 000 hydrographic casts. Global dissipations are 2.0 ± 0.6 TW, consistent with internal wave power sources of 2.1 ± 0.7 TW from tides and wind. Vertically integrated dissipation rates vary by three to four orders of magnitude with elevated values over abrupt topography in the western Indian and Pacific as well as midocean slow spreading ridges, consistent with internal tide sources. But dependence on bottom forcing is much weaker than linear wave generation theory, pointing to horizontal dispersion by internal waves and relatively little local dissipation when forcing is strong. Stratified turbulent bottom boundary layer thickness variability is not consistent with OGCM parameterizations of tidal mixing. Average diffusivities K = (0.3–0.4) × 10−4 m2 s−1 depend only weakly on depth, indicating that ε = KN2/γ scales as N2 such that the bulk of the dissipation is in the pycnocline and less than 0.08-TW dissipation below 2000-m depth. Average diffusivities K approach 10−4 m2 s−1 in the bottom 500 meters above bottom (mab) in height above bottom coordinates with a 2000-m e-folding scale. Average dissipation rates ε are 10−9 W kg−1 within 500 mab then diminish to background deep values of 0.15 × 10−9 W kg−1 by 1000 mab. No incontrovertible support is found for high dissipation rates in Antarctic Circumpolar Currents or parametric subharmonic instability being a significant pathway to elevated dissipation rates for semidiurnal or diurnal internal tides equatorward of 28° and 14° latitudes, respectively, although elevated K is found about 30° latitude in the North and South Pacific.

scholarly journals The Impact of Subtidal Circulation on Internal Tide Generation and Propagation in the Philippine Sea

2014 ◽  
Vol 44 (5) ◽  
pp. 1386-1405 ◽  
Author(s):  
Colette G. Kerry ◽  
Brian S. Powell ◽  
Glenn S. Carter
Keyword(s):  
Energy Levels ◽  
Internal Tide ◽  
Equation Model ◽  
Luzon Strait ◽  
Internal Tides ◽  
Philippine Sea ◽  
Subtidal Circulation ◽  
Tide Propagation ◽  
Mariana Arc ◽  
The Impact

Abstract This study examines the effects of the subtidal circulation on the generation and propagation of the M2 internal tide in the Philippine Sea using a primitive equation model. Barotropic to baroclinic conversion at the Luzon Strait is found to vary due to the background circulation changes over the generation site and the changing influence of remotely generated internal tides from the Mariana Arc. The varying effect of remotely generated waves results from both changing generation energy levels at the Mariana Arc and variability in the propagation of the internal tides across the Philippine Sea. The magnitude and direction of the depth-integrated baroclinic energy fluxes vary temporally, due to a combination of changing generation, propagation, and dissipation. Spatial patterns of internal tide propagation near the Luzon Strait are influenced by the locations of mesoscale eddies to the east and west of the strait. The results provide insight into the mechanisms of variability of the baroclinic tides and highlight the importance of considering both the remotely generated internal tides and the subtidal dynamics to estimate internal tide energetics.

scholarly journals Internal Tide Convergence and Mixing in a Submarine Canyon

2017 ◽  
Vol 47 (2) ◽  
pp. 303-322 ◽  
Author(s):  
Amy F. Waterhouse ◽  
Jennifer A. Mackinnon ◽  
Ruth C. Musgrave ◽  
Samuel M. Kelly ◽  
Andy Pickering ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Internal Wave ◽  
Wave Energy ◽  
Internal Tide ◽  
Submarine Canyon ◽  
Internal Tides ◽  
North Coast ◽  
Semidiurnal Tide ◽  
The North ◽  
Tidally Driven

AbstractObservations from Eel Canyon, located on the north coast of California, show that elevated turbulence in the full water column arises from the convergence of remotely generated internal wave energy. The incoming semidiurnal and bottom-trapped diurnal internal tides generate complex interference patterns. The semidiurnal internal tide sets up a partly standing wave within the canyon due to reflection at the canyon head, dissipating all of its energy within the canyon. Dissipation in the near bottom is associated with the diurnal trapped tide, while midwater isopycnal shear and strain is associated with the semidiurnal tide. Dissipation is elevated up to 600 m off the bottom, in contrast to observations over the flat continental shelf where dissipation occurs closer to the topography. Slope canyons are sinks for internal wave energy and may have important influences on the global distribution of tidally driven mixing.

scholarly journals Internal Solitary Waves in the Andaman Sea Revealed by Long-term Mooring Observations

2021 ◽  
Author(s):  
Yunchao Yang ◽  
Xiaodong Huang ◽  
Wei Zhao ◽  
Chun Zhou ◽  
Siwei Huang ◽  
...  
Keyword(s):  
Solitary Waves ◽  
Internal Tide ◽  
Equatorial Indian Ocean ◽  
Temporal Variations ◽  
Andaman Sea ◽  
Internal Solitary Waves ◽  
Release Mechanism ◽  
Annual Variations ◽  
Northern Portion

AbstractThe complex behaviors of internal solitary waves (ISWs) in the Andaman Sea were revealed using data collected over nearly 22-month-long observation period completed by two moorings. Emanating from the submarine ridges northwest of Sumatra Island and south of Car Nicobar, two types of ISWs, referred to as S- and C-ISWs, respectively, were identified in the measurements, and S-ISWs were generally found to be stronger than C-ISWs. The observed S- and C-ISWs frequently appeared as multi-wave packets, accounting for 87% and 43% of their observed episodes, respectively. The simultaneous measurements collected by the two moorings featured evident variability along the S-ISW crests, with the average wave amplitude in the northern portion being 36% larger than that in the southern portion. The analyses of the arrival times revealed that the S-ISWs in the northern portion occurred more frequently and arrived more irregularly than those in the southern portion. Moreover, the temporal variability of ISWs drastically differed on monthly and seasonal time scales, characterized by relatively stronger S-ISWs in spring and autumn. Over interannual time scale, the temporal variations in ISWs were generally subtle. The monthly-to-annual variations of ISWs could be mostly explained by the variability in stratification, which could be modulated by the monsoons, the winds in equatorial Indian Ocean and the mesoscale eddies in Andaman Sea. From careful analyses preformed based on the long-term measurements, we argued that the observed ISWs were likely generated via internal tide release mechanism and their generation processes were obviously modulated by background circulations.

On the Generation and Evolution of Internal Solitary Waves in the Andaman Sea

2021 ◽  
Author(s):  
Yujun Yu ◽  
Shuya Wang ◽  
Xu Chen
Keyword(s):  
Solitary Waves ◽  
Influence Factors ◽  
Internal Tides ◽  
Andaman Sea ◽  
Internal Solitary Waves ◽  
Minor Effect ◽  
Nicobar Island ◽  
Tidal Forcing ◽  
Topographic Features ◽  
Low Froude Number

<p>Internal Solitary Waves (ISW) are ubiquitous in the Andaman Sea as revealed by Synthetic Aperture Radar (SAR) images, but their generation mechanism and corresponding influence factors remain unknown. Based on a non-hydrostatic two-dimensional model, the generation of ISW across the channel between the Batti Malv Island and the Car Nicobar Island is investigated. Influences of the topography characteristics, seasonal stratification and tidal forcing are analyzed with a series of sensitivity runs. The simulated results indicate that no apparent ISW appear near the ridge because of small tidal excursion and low Froude number. Instead, they are evolved from the disintegrated internal tides which gradually steepen due to nonlinearity during propagation. East-west asymmetry of ISWs is revealed, which can be attributed to different topographic features on the two sides of the ridge. Two sills on the east side of the ridge further complicate the generation of eastward-propagating internal tides, resulting in the enhancement of ISWs in the Andaman Sea. Seasonally varying stratification has minor effect on the generation and evolution of ISWs. In addition, generation of ISW is mainly contributed by semidiurnal tidal forcing, while diurnal forcing only generates linear internal tides.</p>

Three dimensional simulation on the generation and propagation of internal tides and solitary waves northeast of Taiwan Island

2021 ◽  
Author(s):  
Wenjia Min ◽  
Zhenhua Xu ◽  
Qun Li ◽  
Peiwen Zhang ◽  
Baoshu Yin
Keyword(s):  
Continental Slope ◽  
Solitary Waves ◽  
Okinawa Trough ◽  
Satellite Image ◽  
Three Dimensional ◽  
Internal Tides ◽  
Internal Solitary Waves ◽  
Strong Mixing ◽  
Dimensional Simulation ◽  
Shelf Region

<p>The slope area northeast of Taiwan was known as a hotspot for internal tides and internal solitary waves (ISWs), while their specific sources and generation mechanism of ISWs remain unclear. We investigate the generation and evolution processes of internal tides and ISWs with realistic configuration based on the high resolution non-hydrostatic numerical simulations. The ISWs northeastern Taiwan show a complex pattern according to the satellite image and our numerical results. ISWs propagate to various direction, and both shoreward and seaward propagating ISWs are generated on the continental slope. The ISWs observed on the continental slope-shelf region northeastern Taiwan can be generated by two ways. One is the local tide-topography interaction, and the other is the disintegration of remote internal tides generated over the I-Lan Ridge. The generated internal tides propagate northward to the Okinawa Trough, and can reach the continental slope-shelf region. During the propagation of the internal tides, the internal tides start to steepen and internal solitary waves are formed about 80 km north of I-Lan Ridge. The amplitude of the generated internal solitary waves is about 30 m. Furthermore, the Kuroshio is important to modulate the propagation and evolution of internal tides and ISWs, especially to the complexity of the ISW spatial pattern. We revealed most of the generated internal wave energy is dissipated locally over the double-canyon region, and strong mixing occur over the canyons.</p>

Incoherent Nature of M2 Internal Tides at the Hawaiian Ridge

2011 ◽  
Vol 41 (11) ◽  
pp. 2021-2036 ◽  
Author(s):  
N. V. Zilberman ◽  
M. A. Merrifield ◽  
G. S. Carter ◽  
D. S. Luther ◽  
M. D. Levine ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Low Frequency ◽  
Internal Tide ◽  
Internal Tides ◽  
Ridge Crest ◽  
Tide Propagation ◽  
Phase Variations ◽  
Perturbation Pressure ◽  
Work Done ◽  
The Impact

Abstract Moored current, temperature, and conductivity measurements are used to study the temporal variability of M2 internal tide generation above the Kaena Ridge, between the Hawaiian islands of Oahu and Kauai. The energy conversion from the barotropic to baroclinic tide measured near the ridge crest varies by a factor of 2 over the 6-month mooring deployment (0.5–1.1 W m−2). The energy flux measured just off the ridge undergoes a similar modulation as the ridge conversion. The energy conversion varies largely because of changes in the phase of the perturbation pressure, suggesting variable work done on remotely generated internal tides. During the mooring deployment, low-frequency current and stratification fluctuations occur on and off the ridge. Model simulations suggest that these variations are due to two mesoscale eddies that passed through the region. The impact of these eddies on low-mode internal tide propagation over the ridge crest is considered. It appears that eddy-related changes in stratification and perhaps cross-ridge current speed contribute to the observed phase variations in perturbation pressure and hence the variable conversion over the ridge.

scholarly journals Modelling internal solitary waves on the Australian North West Shelf

2006 ◽  
Vol 57 (3) ◽  
pp. 265 ◽  
Author(s):  
Roger Grimshaw ◽  
Efim Pelinovsky ◽  
Yury Stepanyants ◽  
Tatiana Talipova
Keyword(s):  
Solitary Waves ◽  
Vries Equation ◽  
Internal Tide ◽  
Internal Solitary Waves ◽  
Linear Wave ◽  
North West ◽  
Non Linear ◽  
Wave Path ◽  
Simulation Results ◽  
Synergetic Action

The transformation of the non-linear internal tide and the consequent development of internal solitary waves on the Australian North West Shelf is studied numerically in the framework of the generalised rotation-modified Korteweg–de Vries equation. This model contains both non-linearity (quadratic and cubic), the Coriolis effect, depth variation and horizontal variability of the density stratification. The simulation results demonstrate that a wide variety of non-linear wave shapes can be explained by the synergetic action of non-linearity and the variability of the hydrology along the wave path.

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