Internal solitary waves on the NW African shelf: A heuristic approach to localize diapycnal mixing hotspots

Gentil, Mathieu; Floc'H, France; Meunier, Thomas; Ruiz‐Angulo, Angel; Roudaut, Gildas; Perrot, Yannick; Lebourges‐Dhaussy, Anne

doi:10.1016/j.csr.2021.104492

Cited by 3 publications

(3 citation statements)

References 63 publications

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“…The ability of the waves to transport remotely the internal tide energy benefits local ecosystems once the waves break on the shore. Despite giving important mechanisms which support productivity due to nutrient enrichment for the pelagic system [18,19], the wave breaking may potentially harm the coastal environment due to pollutant resuspension in the sediments [20].…”

Section: Backgroundsmentioning

confidence: 99%

Characteristics of Internal Solitary Waves near Its Generation Site in the Lombok Strait, Indonesia

Purwandana,

Edikusmanto,

Utari

et al. 2023

Positron

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Evidence of internal solitary waves (ISWs) formation through the Lee wave mechanism in the Lombok Strait was revealed from the echosounder measurements conducted in November 2017. This study is aimed to characterize the property of ISW packet formed around ~30 km away from the generation site, in the southern part of the strait above the Nusa Penida Sill (NPS), by employing Korteweg-de Vries (KdV) solution. The packet can be categorized as the early stage of ISW formation, consisting of two waves of depression, with typical amplitude of 30 m and 10 m, for the first and second wave, respectively. The waves propagated northward with a typical phase speed of ~1.2 m∙s -1. The waves drive a maximum horizontal velocity anomaly of ~0.8 m∙s - 1 and a vertical velocity anomaly of ~10 cm∙s -1. The amplitude of the ISW packet will be potentially amplified during their propagation away from the strait. This study provides an observational based understanding on the early stage of internal tides evolution in the Lombok Strait, particularly highlights the energy transfer of internal tides through the propagation of internal solitary waves.

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Section: Backgroundsmentioning

confidence: 99%

Characteristics of Internal Solitary Waves near Its Generation Site in the Lombok Strait, Indonesia

Purwandana,

Edikusmanto,

Utari

et al. 2023

Positron

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“…Typically, ISWs consist of a single isolated wave of elevation or depression, depending on the background state [2]. ISWs are of great importance to various scientific issues, including sound propagation [3], pollutant transport [4], and primary productivity [5]. ISWs carry a lot of energy and can cause strong density displacement, which is serious threat to underwater structures and submarines [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Internal Solitary Waves in the Timor Sea Observed by SAR Satellite

et al. 2023

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Internal solitary waves (ISWs) with features such as large amplitude, short period, and fast speed have great influence on underwater thermohaline structure, nutrient transport, and acoustic signal propagation. The characteristics of ISWs in hotspot areas have been revealed by satellite images combined with mooring observation. However, the ISWs in the Timor Sea, which is located in the outflow of the ITF, have not been studied yet and the characteristics are unrevealed. In this study, by employing the Synthetic Aperture Radar (SAR) images taken by the Sentinel-1 satellite from 2017 to 2022, the temporal and spatial distribution characteristics of ISWs in the Timor Sea are analyzed. The results show that most of ISWs appear in Bonaparte basin and its vicinity. The average wavelength of the ISWs is 248 m, and most of the wave lengths are less than 400 m. The peak line of ISWs is longer in deeper water. The underwater structures of two typical ISWs are reconstructed based on the Korteweg–de Vries (KdV) equation combined with mooring observation. This shows that, compared with the two-layer model, the continuous layered model is more suitable for reconstructing the underwater structures of ISWs. Further analysis shows that both the rough topography and the spring-neap tides contribute to the generation of ISWs in the Timor Sea. This study fills a gap in knowledge of ISWs in regional seas, such as the Timor Sea.

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“…Within this perspective, active acoustic is a powerful tool since echosounders can capture fine-scale oceanographic structures typically 45 attributed to biological scattering or turbulent structures (Bertrand et al, 2014;Klymak and Moum, 2003;Lavery et al, 2003;Pingree and Mardell, 1985;Stranne et al, 2018;Trevorrow, 1998). Indeed, acoustics allow covering large areas with a single signal providing continuous (along the route of the vessel and/or per sampling station) and high resolution on a variety of biotic (Benoit-Bird and Lawson, 2016;Bertrand et al, 2014) and abiotic properties such as the oxycline (Bertrand et al, 2010), internal waves (Gentil et al, 2021;Grados et al, 2016;Holbrook et al, 2009; 50 Holbrook and Fer, 2005;Orr et al, 2000), submesoscale to mesoscale eddies (Biescas et al, 2008;Grados et al, 2016;Ménesguen et al, 2012), thermocline (Ker et al, 2016;Stranne et al, 2018) and thermohaline staircases (Biescas et al, 2008;Fer et al, 2010;Ross and Lueck, 2005;Stranne et al, 2017).…”

Section: Introduction 25mentioning

confidence: 99%

On the use of acoustic data to characterise the thermohaline stratification in a tropical ocean

Assunção

Lebourges‐Dhaussy

Silva³

et al. 2021

Preprint

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Abstract. The use of active acoustic to monitor abiotic structures and processes in the ocean have been gaining ground in oceanography. In some systems, acoustics allow the robust estimation of the depth of the pycnocline or thermocline either directly or indirectly when the physical structures drive the one of organisms. Here, we examined the feasibility of extracting the thermohaline structure (mixed-layer depth, upper and lower thermocline) from echosounder data collected in the oligotrophic Southwestern tropical Atlantic region at two seasons (spring and fall), more precisely in two areas with different thermohaline conditions, at both day and night. For that, we tested three approaches: (i) the vertical extension of the epipelagic community; (ii) the use of acoustic gradients; and (iii) a cross-wavelet approach. Results show that, even if the thermohaline structure impacts the vertical distribution of acoustic scatters, the resultant structuring did not allow for a robust estimation of the thermohaline limits indicating that other oceanographic or biological processes are acting. This result prevents for a fine-scale representation of the upper-layer turbulence from acoustic data. However, studying the proportion of acoustic biomass within each layer provides interesting insights on ecosystem structure in different thermohaline, seasonal and diel scenarios.

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Internal solitary waves on the NW African shelf: A heuristic approach to localize diapycnal mixing hotspots

Cited by 3 publications

References 63 publications

Characteristics of Internal Solitary Waves near Its Generation Site in the Lombok Strait, Indonesia

Characteristics of Internal Solitary Waves near Its Generation Site in the Lombok Strait, Indonesia

Characteristics of Internal Solitary Waves in the Timor Sea Observed by SAR Satellite

On the use of acoustic data to characterise the thermohaline stratification in a tropical ocean

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