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 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 Tides in the Southwestern Atlantic off Brazil: Observations and Numerical Modeling

2007 ◽  
Vol 37 (6) ◽  
pp. 1512-1526 ◽  
Author(s):  
Adriene F. Pereira ◽  
Belmiro M. Castro
Keyword(s):  
Continental Shelf ◽  
Three Dimensional ◽  
Internal Tide ◽  
Equation Model ◽  
Shelf Break ◽  
Internal Tides ◽  
Southwestern Atlantic ◽  
Model Response ◽  
Southwestern Atlantic Ocean ◽  
Vertical Displacements

Abstract Data collected from moored instruments, deployed over the southeastern Brazilian continental shelf during the summer and winter months of 2001, show internal tide activity near the shelf break. To help to elucidate the observations, a fully three-dimensional nonlinear primitive equation model is applied to simulate the regional barotropic and baroclinic tides. Two semidiurnal (M2 and S2) and two diurnal (K1 and O1) tidal frequencies are considered. Tidal surface elevations are relatively small over the whole modeled area, reaching maximum values of about 0.40 m for M2 and 0.11 m for O1. Comparison between observed and computed tide elevation and Greenwich phase shows reasonable agreement. When the baroclinic response of the model is investigated, stratification is prescribed using summer and winter climatology data of potential density. In this case, the model response to summer and winter stratifications is very similar and internal tides are generated over the shelf break and slope, with vertical displacements up to 25 m, and seaward propagation. Modeled semidiurnal tidal ellipses agree well with winter and summer observations. Observed diurnal tidal ellipses in the middle of the continental shelf and close to the shelf break during summer show an intensification through the water column that could not be represented by the model. Estimates of the total baroclinic M2 offshore energy flux are about 3.5 and 0.5 MW considering winter and summer stratifications, respectively. Although these quantities are three orders of magnitude less than that estimated for regions known for intense internal tides, they refer to offshore fluxes computed for a very small section of the southeastern Brazilian shelf. This is the first published investigation into internal tides in the southwestern Atlantic Ocean off Brazil.

Statistics of Internal Tide Bores and Internal Solitary Waves Observed on the Inner Continental Shelf off Point Sal, California

2018 ◽  
Vol 48 (1) ◽  
pp. 123-143 ◽  
Author(s):  
John A. Colosi ◽  
Nirnimesh Kumar ◽  
Sutara H. Suanda ◽  
Tucker M. Freismuth ◽  
Jamie H. MacMahan
Keyword(s):  
Continental Shelf ◽  
Energy Flux ◽  
Solitary Waves ◽  
Internal Tide ◽  
Propagation Loss ◽  
Internal Solitary Waves ◽  
Time Behavior ◽  
Time Duration ◽  
Match Filter ◽  
Inner Continental Shelf

AbstractMoored observations of temperature and current were collected on the inner continental shelf off Point Sal, California, between 9 June and 8 August 2015. The measurements consist of 10 moorings in total: 4 moorings each on the 50- and 30-m isobaths covering a 10-km along-shelf distance and an across-shelf section of moorings on the 50-, 40-, 30-, and 20-m isobaths covering a 5-km distance. Energetic, highly variable, and strongly dissipating transient wave events termed internal tide bores and internal solitary waves (ISWs) dominate the records. Simple models of the bore and ISW space–time behavior are implemented as a temperature match filter to detect events and estimate wave packet parameters as a function of time and mooring position. Wave-derived quantities include 1) group speed and direction; 2) time of arrival, time duration, vertical displacement amplitude, and waves per day; and 3) energy density, energy flux, and propagation loss. In total, over 1000 bore events and over 9000 ISW events were detected providing well-sampled statistical distributions. Statistics of the waves are rather insensitive to position along shelf but change markedly in the across-shelf direction. Two compelling results are 1) that the probability density functions for bore and ISW energy flux are nearly exponential, suggesting the importance of interference and 2) that wave propagation loss is proportional to energy flux, thus giving an exponential decay of energy flux toward shore with an e-folding scale of 2–2.4 km and average dissipation rates for bores and ISWs of 144 and 1.5 W m−1, respectively.

Upwelling by internal tides and kelvin waves at the continental shelf break on the Great Barrier Reef

1983 ◽  
Vol 34 (1) ◽  
pp. 65 ◽  
Author(s):  
E Wolanski ◽  
GL Pickard
Keyword(s):  
Continental Shelf ◽  
Great Barrier Reef ◽  
Low Frequency ◽  
Kelvin Waves ◽  
Shelf Break ◽  
Internal Tides ◽  
Wind Component ◽  
Barrier Reef ◽  
Tidal Period ◽  
Continental Shelf Break

A time series of 50 days duration was obtained of sea levels and winds and of temperature and currents at six depths from 27 to 104 m at 18�19'S.,147�21'E. on the continental shelf break between the Great Barrier Reef and the Coral Sea. The sea-level signal had a predominantly mixed solar and lunar semidiurnal tidal period. The currents consisted of a semidiurnal tidal component oriented primarily cross-shelf, except near the sea floor, superimposed on a low-frequency, predominantly longshore, southward component, coherent with depth, in geostrophic balance, and modulated by the longshore wind component Large fluctuations in temperature were observed, consisting of a low-frequency component, possibly generated by internal Kelvin waves, and iiucruarions of predominantiy solar semidiurnai iidai period. The latter fiiictuations are interpreted as evidence of internal tides of amplitude up to 110 m that may be generated by the interaction of the longshore currents with topographic irregularities in the shelf. It is suggested that, during any long-term studies of water properties near the shelf break, some additional monitoring of short-term temporal variations should be carried out to avoid data aliasing by internal tides. The bottom boundary layer appears to be very active in vertical mixing. Internal tides may be very important in introducing other water components, e.g. nutrients, to the outer Great Barrier Reef.

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.

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