Refraction of the M2 internal tides by mesoscale eddies in the South China Sea

Zheng, Guo; Wang, Shuya; Cao, Anzhou; Xie, Jieshuo; Song, Jinbao; Guo, Xinyu

doi:10.1016/j.dsr.2022.103946

Cited by 12 publications

(10 citation statements)

References 51 publications

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“…The modulation effect of anticyclonic eddies the propagation of the semidiurnal internal tide from different source regions in the northern SCS was investigated using numerical modeling. The conclusion that the influence of background flow on the semidiurnal internal tide propagation is greater than that of stratification, as obtained by Guo et al (2023) [45], is consistent with our findings. It is further concluded that anticyclonic eddy passage accelerates the propagation of the semidiurnal internal tide from the Luzon Strait source region while simultaneously retarding the propagation of the semidiurnal internal tide from the southern Taiwan Strait continental slope region.…”

Section: Discussionsupporting

confidence: 92%

“…Compared with the PIES observations in Wang et al, 2023 [23], both semidiurnal and M2 internal tide amplitude changed largely in March, which may indicate the influence of the background field on the interference. Based on previous studies [23,34,45], we hypothesize that the intensified interference phenomenon may be attributed to the passage of mesoscale eddies, which increase the phase difference of semidiurnal internal tide propagation from two source regions within the observation area. Therefore, to better verify our hypothesis, we conducted ray-tracing experiments to investigate this phenomenon.…”

Section: Discussionmentioning

confidence: 91%

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Semidiurnal Internal Tide Interference in the Northern South China Sea

Wang,

Li,

Huang

2024

JMSE

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Multiwave interference plays a crucial role in shaping the spatial variations of internal tides. Based on a combination of in situ mooring and altimeter data, interference of semidiurnal internal tides was investigated in the northern South China Sea. Mooring observations indicate the observed kinetic-to-potential energy ratio and group speed are both relatively lower than the theoretical values of mode-1 semidiurnal internal tides, indicating the presence of partly-standing waves. This is consistent with the altimeter result that the mooring was located at the antinode within the interference pattern formed by the superposition of the westward and southward semidiurnal internal tides from the Luzon Strait and the continental slope of the southern Taiwan Strait. However, the kinetic-to-potential energy ratio and group velocity were notably changed when an anticyclonic eddy passed by the mooring. By employing the ray-tracing method, we identified that mesoscale processes may induce a phase difference in the semidiurnal internal tides between the Luzon Strait and the continental slope of the southern Taiwan Strait. This alteration further leads to changes in the positions of nodes and antinodes within the interference pattern of the semidiurnal internal tides.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 91%

Semidiurnal Internal Tide Interference in the Northern South China Sea

Wang,

Li,

Huang

2024

JMSE

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“…Previous studies have investigated the interaction of internal tides with background currents, i.e. midlatitude and equatorial jets, as well as mesoscale turbulence and eddies causing time variable refraction and deflection of the internal tide (Park and Watts, 2006;Ponte and Klein, 2015;Kelly and Lermusiaux, 2016;Magalhães et al, 2016;Buijsman et al, 2017;Tchilibou et al, 2022;Guo et al, 2023). Most recently, Guo et al (2023) correlated the refraction of the internal tide with mesoscale-eddy driven phase speed variations.…”

Section: Ssh Spectral Signaturementioning

confidence: 99%

“…midlatitude and equatorial jets, as well as mesoscale turbulence and eddies causing time variable refraction and deflection of the internal tide (Park and Watts, 2006;Ponte and Klein, 2015;Kelly and Lermusiaux, 2016;Magalhães et al, 2016;Buijsman et al, 2017;Tchilibou et al, 2022;Guo et al, 2023). Most recently, Guo et al (2023) correlated the refraction of the internal tide with mesoscale-eddy driven phase speed variations. Further, the authors show that the refraction of the internal tidal beam is rather associated with the currents of the mesoscale eddies rather than mesoscale-eddy driven stratification changes.…”

Section: Ssh Spectral Signaturementioning

confidence: 99%

“…In addition, incoherence occurs when the propagating internal tide interacts with the background (varying) circulation, i.e. mid-latitude and equatorial jets, as well as mesoscale features such as eddies (Park and Watts, 2006;Dunphy and Lamb, 2014;Dunphy et al, 2017;Ponte and Klein, 2015;Kelly and Lermusiaux, 2016;Magalhães et al, 2016;Buijsman et al, 2017;Tchilibou et al, 2022;Guo et al, 2023). Using idealized numerical experiments, Ponte and Klein (2015) studied the passage of low-mode internal tides through a turbulent mesoscale eddy field.…”

Section: Introductionmentioning

confidence: 99%

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Regional modeling of internal tide dynamics around New Caledonia: energetics and sea surface height signature

Bendinger

Cravatte

Gourdeau

et al. 2023

Preprint

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Abstract. The Southwestern Tropical Pacific exhibits a complex bathymetry and represents a hot spot of internal tide generation. Based on a tailored high-resolution regional model, we investigate for the first time the internal tide field around the New Caledonia islands through energy budgets that quantify the internal tide generation, propagation, and dissipation. A total of 15.97 GW is converted from the barotropic to the baroclinic tide with the main conversion sites associated with the most prominent bathymetric structures such as continental slopes and narrow passages in the north (2.17 GW) and ridges and seamounts south of New Caledonia (3.92 GW). The bulk of baroclinic energy is generated in shallow waters around 500 m depth and on critical to supercritical slopes highlighting the limitations of linear semi-analytical models in those areas. Despite the strongly dominant mode-1 generation, more than 50 % of the locally generated energy dissipates in the near-field close to the generation sites. The remaining energy propagates within well-defined tidal beams with baroclinic energy fluxes of up to 30 kW m−1 toward the open ocean, strongly dominated by mode-1. The energetic mesoscale eddy activity in the region appears to be the main source of tidal incoherence. Locally, mesoscale eddy-driven stratification changes induce variations of the conversion term. In the far-field, incoherence of the energy flux arises through the interaction of the tidal beam with the eddying background flow. The New Caledonia site represents a challenge for SWOT (Surface Water Ocean Topography) observability of meso- and submesoscale dynamics in the presence of internal tides with sea surface height signatures > 6 cm. We show that a correction of the coherent baroclinic tide may improve the observability range by shifting the transition scale between balanced and unbalanced flow in winter from 180 km to 50–80 km. In contrast, in summer observability increases only marginally due to the seasonally amplified signature of the incoherent tide at scales below 100 km.

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