Generation of second-mode internal solitary waves during winter in the northern South China Sea

Liang, Jiajuan; Li, Xiaoming

doi:10.1007/s10236-019-01246-6

Cited by 7 publications

(4 citation statements)

References 36 publications

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“…Liang et al. (2018) found that mode 2 waves may arise when an initial mode 1 waves propagate into a horizontally varying stratification regime, and Liang & Li (2019) indicated from field observations that a convex internal solitary wave may be generated by a shoaling semidiurnal mode 2 internal tide.…”

Section: Introductionmentioning

confidence: 99%

Generation of mode 2 internal waves by the interaction of mode 1 waves with topography

2019

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Oceanic internal waves can be decomposed into an infinite set of modes, and the dominant internal mode 1 waves have been extensively investigated. Although mode 2 waves have been observed, they have not received comparable attention, especially the generation mechanisms. In this work, we examine the generation of mode 2 internal waves by the interaction of mode 1 waves with topography. We use a coupled linear long-wave theory with mode coupling through topography, combined with evolution using a Korteweg–de Vries model, to predict the mode 2 wave amplitude, in an ideal three-layer fluid model, in a smooth density stratification and in two realistic oceanic settings. We find that the mode 2 wave amplitude is usually much smaller than the incident mode 1 wave amplitude and is quite sensitive to the pycnocline thickness, topographic slope and background stratification.

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Section: Introductionmentioning

confidence: 99%

Generation of mode 2 internal waves by the interaction of mode 1 waves with topography

2019

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“…Yang et al first reported that Marine measured data of multiple solitary waves within the second baroclinic mode on the continental slope of the northern South China Sea (SCS) [9]. Liang studied the generation mechanism of the field data of the mode -2 ISWs reported by Yang et al, the results shows that the Mode-2I SW is generated by the half-day internal tide (IT) [10]. Magalhaes et al observed five continuous and regularly spaced envelope of Mode-2 ISWs simultaneously in Andaman Sea by using remote sensing technology, results show that Mode-2 ISW may have been overlooked due to their small size in previous remote sensing observations.…”

Section: Figurementioning

confidence: 99%

Experimental Investigation on a convex Mode-2 internal solitary wave and its induced flow field

Wang,

Du,

Wei

et al. 2024

J. Phys.: Conf. Ser.

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The second mode internal solitary wave (Mode-2 ISW) and its wave-induced flow field structure are investigated by conducted physical experiments in a large stratified fluid flume. The Mode-2 ISW is generated by the method of the gravity collapse of fluid, and the measurements of its wave-flow structure are obtained by the combined method of conductivity probe array and particle image velocimetry (PIV). The flow field structure and its influencing factors were analysed quantitatively. The results reveal the characteristic of the Mode-2 ISW waveform and density field and the effect of the wave amplitude on the flow and shear characteristics of induced flow field.

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“…In the Mascarene Ridge and the Andaman Sea, the impact of the ISW beam with the pycnocline is identified as the mechanism responsible for the generation of mode-2 ISWs subsequently developing shorter-scale waves (wave tails with mode-1 structure) (da Silva et al, 2015;Magalhães and da Silva, 2018). Potential mechanisms for the generation of mode-2 waves have been illustrated and they include the instability of shoaling mode-1 waves (Helfrich and Melville, 1986) and their interaction with localized sills (Lamb and Warn-Varnas, 2015), the propagation of mode-1 waves into a horizontally varying stratification regime (Liang et al, 2018), and shoaling mode-2 semi-diurnal internal tides (Liang and Li, 2019). The mode-2 waves receive less attention in the literature compared to mode 1, although some works document mode-2 waves propagating with a mode-1 tail in Knight Inlet, British Columbia (Farmer and Smith, 1980) and/or illustrate their occurrence following mode-1 waves in the South China Sea (Yang et al, 2009;Liu et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal variability in mode-1 and mode-2 internal solitary waves from MODIS-Terra sun glint off the Amazon shelf

de Macedo,

Koch-Larrouy,

da Silva

et al. 2023

Ocean Sci.

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Abstract. The Amazon shelf is a key region for intense internal tides (ITs) and nonlinear internal solitary wave (ISWs) generation associated with them. The region shows well-marked seasonal variability (from March to July, MAMJJ, and from August to December, ASOND) of the circulation and stratification, which can both induce changes in the ISW physical characteristics. The description of the seasonal and neap–spring tidal variability in the ISWs off the Amazon shelf is performed for the first time using a meaningful data set composed of 140 MODIS-Terra imagery from 2005 to 2021, where about 500 ISW signatures were identified in the sun glint region. Previous studies have documented the existence of mode-1 ISWs, but the region appears as a newly described hotspot for mode-2 ISWs. ISW packets separated by typical mode-1 (95–170 km; 2.1–3.8 m s−1) and mode-2 (46–85 km; 1.0–1.9 m s−1) IT wavelengths have been identified and mapped coming from different IT generation sites. For each ISW, a group of waves (3 to 10) is generally follows the largest crest. The intra-packet distance between each wave in the group is about 10 to 20 km. Regions of higher occurrence of ISWs are spaced by a IT mode-1 wavelength. We make the assumption that it might correspond to the IT reflection beams at the surface, which may generate newer ISWs. The mean mode-1 and mode-2 inter-packet distances do not show significant differences according to their IT generation sites. The ISW activity is higher (more than 60 % of signatures) during spring tides than neap tides. In the region under the influence of the North Equatorial Counter Current (NECC), ISWs are separated by a mean mode-1 IT wavelength which is 14.3 % higher during ASOND than during MAMJJ due to a deeper thermocline and the reinforcement of the NECC. These ISWs are also characterized by a wider inter-packet distance distribution (higher standard deviation) that may be related to the stronger eddy kinetic energy (EKE) during ASOND compared to MAMJJ. The mean inter-packet distance of mode-2 ISWs remains almost unchanged during the two seasons, but the inter-packet distance distribution is wider in ASOND than in MAMJJ as for mode 1. Note that these results need to be treated with caution, as only few occurrences of mode-2 waves were found during MAMJJ. In the region of the NECC, the direction of propagation for all modes is very similar in MAMJJ (about 30∘ clockwise from the north), whereas, for ASOND, the ISWs propagate in a wider pathway (from 0 to 60∘ clockwise from the north), due to a much larger eddy activity. During ASOND, as the background flux goes further east, the inter-packet distances become larger (4 % for mode 1 and 7.8 % for mode 2). These results show that the reinforcement of the NECC in ASOND appears to play a role in diverting the waves towards the east, increasing their phase velocities and their eastern traveling direction component when compared to MAMJJ. Calculations of the IT velocities using the Taylor–Goldstein equation supported our results regarding the presence of ISWs associated with mode-2 ITs and additionally the IT seasonal variability.

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Generation of second-mode internal solitary waves during winter in the northern South China Sea

Cited by 7 publications

References 36 publications

Generation of mode 2 internal waves by the interaction of mode 1 waves with topography

Generation of mode 2 internal waves by the interaction of mode 1 waves with topography

Experimental Investigation on a convex Mode-2 internal solitary wave and its induced flow field

Spatial and temporal variability in mode-1 and mode-2 internal solitary waves from MODIS-Terra sun glint off the Amazon shelf

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