Kinematic parameters of internal waves of the second mode in the South China Sea

Kurkina, Oxana; Talipova, Tatiana; Soomere, Tarmo; Giniyatullin, Ayrat; Kurkin, Andrey

doi:10.5194/npg-2017-20

Cited by 2 publications

(2 citation statements)

References 27 publications

(56 reference statements)

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“…The phase speed for mode‐2 ISWs is about half of that of mode‐1 ISWs. This result agrees with that by Kurkina et al (). The nonlinear effect on the propagation speed is about 6% for mode‐1 ISWs and 9% for mode‐2 ISWs on average.…”

Section: Statistical Features Of Iswssupporting

confidence: 94%

Dynamic and Statistical Features of Internal Solitary Waves on the Continental Slope in the Northern South China Sea Derived From Mooring Observations

et al. 2019

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For investigation of internal solitary waves (ISWs) in the South China Sea (SCS), most cruise observations are concentrated from Luzon Strait to Dongsha Atoll in the northeastern SCS but few on the continental slope far away from the west of Dongsha Atoll. In this study, we use 1‐year long mooring data to determine dynamic and statistical features of the ISWs on the shelf slope of the northwestern SCS. The analysis results of the mooring data reveal that the ocean internal waves on the shelf slope of the northwestern SCS have physical properties of highly nonlinear waves, which are well described by the solutions of the Korteweg‐de Vries equation. The mean nonlinear phase speeds of mode‐1 and mode‐2 ISWs are 1.38 ± 0.14 and 0.66 ± 0.12 m/s, respectively. The major direction of mode‐1 ISWs is northwestward 305° ± 21°. Strong ISW currents force the major direction of total current velocities to turn 67.5° in the upper layer and 135° in the lower layer. The monthly occurrence frequency distribution of ISWs shows a peak in July with a maximum frequency of 16.2% and a trough in March with a minimum frequency of 3.3%. Mode‐2 ISWs appear most in December, accounting for 50% of total mode‐2 ISWs. The largest mode‐2 ISW on record up today with the depressed amplitude as large as 91 m, and the elevated amplitude of 73 m was observed at mooring station. These new findings and new data are of significance to local internal wave prediction model development.

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Section: Statistical Features Of Iswssupporting

confidence: 94%

Dynamic and Statistical Features of Internal Solitary Waves on the Continental Slope in the Northern South China Sea Derived From Mooring Observations

et al. 2019

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“…These are especially well seen at WP3 as the isothermals wiggle in bulge-like features in the upward and downward directions (see isothermals between thick white lines). We note, that similar features have been identified in other studies as being mode-2 solitary-like waves using in situ measurements 16,27,28 and in numerical models 18 . In the particular case of WP3, the corresponding wave features seen in the model are about 10 meters in amplitude and align fairly well (in their direction of propagation) with the SAR observations.…”

Section: Resultssupporting

confidence: 87%

Long lived second mode internal solitary waves in the Andaman Sea

Magalhaes

Silva

Buijsman

2020

Sci Rep

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Internal waves are density oscillations propagating along the ocean's inner stratification, which are now acknowledged as a key constituent of the ocean's dynamics. They usually result from barotropic tides, which flow over bottom topography, causing density oscillations to propagate along the pycnocline with a tidal frequency (i.e. internal tides). These large-scale waves propagate away from their forcing bathymetry and frequently disintegrate into nonlinear short-scale (higher-frequency) internal wave packets. Typically, short-scale internal wave observations in the ocean are associated with vertical structures (in the water column) of the lowest fundamental mode. Higher vertical modes have recently been documented as well, but these are commonly short-lived (up to a few hours). However, unprecedented satellite images showing long-lived short-scale mode-2 internal waves have now been documented in the Andaman Sea, and we report here the companion results of a non-hydrostatic and fully nonlinear numerical model. The simulations reproduce the waves' main characteristics as observed in satellite imagery, and the results suggest a resonant coupling with a larger-scale mode-4 internal tide as an explanation for their long-lived character. Ocean sciences are increasingly relying on satellite remote sensing. In particular, our understanding of Internal Waves (IWs, i.e. density oscillations propagating along the ocean's inner stratification) has seen considerable advances in the last decades owing to satellite imagery 1-3. For instance, IW fields obtained via satellite images are widely used in planning and performing in situ measurements 4,5 , validating numerical models 6,7 , and bridging IWs with other fields of ocean sciences 8,9. The Andaman Sea in the Indian Ocean is a classical study region for IWs dating back to the 19 th century 10 , and staged some of the first dedicated IW measurements in the open ocean 11. This region is in fact unique, in the sense that a series of IW generation hotspots occur along a meridional 1000 km island ridge, each with its own distinct characteristics concerning bathymetry, currents and stratification. According to Osborne and Burch 11 , very large-scale IWs are tidally generated along the ridges of the Andaman and Nicobar Islands which then propagate eastwards while retaining their shape and speed for considerable distances. We note that these waves have typically vertical structures of the fundamental mode (i.e. mode-1), and may be predicted with the shallow water Korteweg and deVries equation, and hence the term Internal Solitary Waves (ISWs) is usually referred to when describing the IWs in the Andaman Sea. Several studies have emerged since Osborn and Burch 11-all of which revealing powerful ISWs in this region which are nonetheless typically mode-1 in their vertical structure 12. However, Synthetic Aperture Radars (SARs) have been recently used 12,13 in documenting the existence of long-lived mode-2 solitary-like waves propagating eastwards along the Ten-Degree Channel of the...

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Kinematic parameters of internal waves of the second mode in the South China Sea

Cited by 2 publications

References 27 publications

Dynamic and Statistical Features of Internal Solitary Waves on the Continental Slope in the Northern South China Sea Derived From Mooring Observations

Dynamic and Statistical Features of Internal Solitary Waves on the Continental Slope in the Northern South China Sea Derived From Mooring Observations

Long lived second mode internal solitary waves in the Andaman Sea

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