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

2021 ◽  
Author(s):  
Yujun Yu ◽  
Jinhu Wang ◽  
Shuya Wang ◽  
Qun Li ◽  
Xu Chen ◽  
...  
Keyword(s):  
Internal Wave ◽  
Solitary Waves ◽  
Spring Tide ◽  
Internal Tides ◽  
Andaman Sea ◽  
Internal Solitary Waves ◽  
Minor Effect ◽  
Nicobar Island ◽  
Topographic Characteristics ◽  
East West

Abstract. Internal solitary waves (ISWs) are ubiquitous in the Andaman Sea, as revealed by synthetic aperture radar (SAR) images, but their generation mechanisms and corresponding influencing factors remain unknown. Based on a nonhydrostatic two-dimensional model, the generation of ISW packets along a transect of a channel lying between Batti Malv Island and Car Nicobar Island is investigated. Additionally, the influences of topographic characteristics, seasonal stratification variables and tidal forcings are analysed through a series of sensitivity runs. The simulated results indicate that bidirectional rank-ordered ISW packets are generated by the nonlinear steepening of internal tides. An east-west ISW asymmetry is observed, which is attributed to distinct topographic characteristics. The surrounding sills are also capable of generating internal wave beams, which modulate the intensity of ISWs. However, the topographic structure of the west flank of the ridge mainly contributes to the suppression of westward ISWs, which decrease the modulating effect of internal wave beams. During spring tide, the generation of ISWs is enhanced. Under neap tide, ISWs are weak, and the east-west ISW asymmetry is less obvious. Moreover, seasonally varied stratification only has a minor effect on the generation and evolution of ISWs.

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>

scholarly journals Internal Solitary Waves in the Andaman Sea: New Insights from SAR Imagery

2018 ◽  
Vol 10 (6) ◽  
pp. 861 ◽  
Author(s):  
Jorge Magalhaes ◽  
José da Silva
Keyword(s):  
Solitary Waves ◽  
Andaman Sea ◽  
Internal Solitary Waves ◽  
Sar Imagery

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 An Empirical Model for Estimating the Geographic Location of Nonlinear Internal Solitary Waves

2009 ◽  
Vol 26 (10) ◽  
pp. 2243-2255 ◽  
Author(s):  
Christopher R. Jackson
Keyword(s):  
Internal Wave ◽  
Solitary Waves ◽  
Phase Speed ◽  
Geographic Location ◽  
Propagation Path ◽  
Internal Solitary Waves ◽  
Propagation Time ◽  
Model Function ◽  
New Approach ◽  
Parameterized Model

Abstract This paper describes the development and performance of a new approach for estimating the geographic location of high-frequency nonlinear internal waves. The approach makes use of the internal wave signatures recorded in satellite imagery to determine the parameters of a model function that relates the internal wave phase speed to depth. The phase speed map produced by the parameterized model function establishes a propagation time and propagation path between an origin and any location in the region of interest. Contours of propagation time represent the internal wave locations for a particular time since generation. The parameters of the model function are found by minimizing the difference between the calculated propagation times and the observed propagation times. This approach is applied to the internal solitary waves observed in the northern portion of the South China Sea west of the Luzon Strait. Propagation time estimates based on this new approach have errors of ±1.32 h (1σ) for depths greater than 1000 m and ±2.55 h (1σ) for all depths over which the waves are observed.

The limiting form of internal waves

1984 ◽  
Vol 394 (1807) ◽  
pp. 329-344 ◽  
Keyword(s):  
Free Surface ◽  
Internal Wave ◽  
Internal Waves ◽  
Solitary Waves ◽  
The Other ◽  
Stokes Wave ◽  
Internal Solitary Waves ◽  
Two Dimensional ◽  
Extreme Form ◽  
Eddy Formation

The bifurcation of two-dimensional internal solitary waves in a perfect density stratified fluid between horizontal walls under gravity is studied near to a point of incipient eddy formation. It is shown that eddies do not attach to the walls. Moreover, along the bifurcating branch there is always a flow with a singular cusped streamline before the formation of eddies. This flow with the cusped streamline is an example of what we call an internal wave of limiting form, by analogy with the Stokes wave of extreme form in the free surface problem. Two examples are given where the primary density stratification ensures the existence of a limiting wave of depression in one case, and of elevation in the other.

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.

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>

scholarly journals Internal solitary waves in the Northwest Sumatra Sea-Indonesia: from observation and modeling

2021 ◽  
Vol 944 (1) ◽  
pp. 012056
Author(s):  
I A Prasetya ◽  
A S Atmadipoera ◽  
S Budhiman ◽  
U C Nugroho
Keyword(s):  
Solitary Waves ◽  
High Tide ◽  
Tidal Currents ◽  
Internal Tides ◽  
Sea Surface ◽  
Radar Signal ◽  
Internal Solitary Waves ◽  
Tidal Waves ◽  
Submarine Ridge ◽  
Lee Waves

Abstract >The southern Andaman waters has been well known as one of the strongest generating and propagating area of internal solitary waves (ISWs), generated by semidiurnal barotropic tidal currents that impinge submarine ridge offshore western Weh. This study aims to investigate sea surface features of internal tides and tidal current around the submarine ridge and adjacent Weh-Aceh waters, derived from satellite imagery datasets (January-May 2018) and CROCO model-output datasets. The results show that sea surface signatures of ISWs are characterized by a strong radar signal backscattering of a dense ripple package in the generating area and two groups of ISWs arch in the propagating area, where the distance of the package groups and wavelengths vary 60-80 km and 9-163 km, respectively. Observed ISWs in March 2018 was 31. The satellite and model datasets suggest that generating area of internal waves is confined over the Breuh ridge. Here, the very strong semidiurnal (M2) barotropic tidal currents of 0.5-5.0 m/s are observed. During high-tide, amplified barotropic tidal currents acrossing the ridge flow partly southeastward into the Weh-Breuh passage. The model suggests that generating internal tidal waves over the ridge are manifested by strong vertical perturbation of isopycnal and current stratifications in the Lee-waves area.

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