An investigation of the properties of low-frequency internal waves in the northeastern China Seas

1989 ◽  
Vol 7 (4) ◽  
pp. 289-299 ◽  
Author(s):  
Fang Xinhua ◽  
Zhang Yulin ◽  
Sun Haili ◽  
Ye Jianhua
Keyword(s):  
Internal Waves ◽  
Low Frequency ◽  
Northeastern China ◽  
China Seas

Low‐frequency reverberation signal in shallow water in presence of internal waves

2004 ◽  
Vol 115 (5) ◽  
pp. 2551-2551
Author(s):  
Boris Katsnelson ◽  
Sergey Pereselkov ◽  
Valery Petnikov
Keyword(s):  
Shallow Water ◽  
Internal Waves ◽  
Low Frequency

Low-frequency sound scattering by internal waves in the ocean

2006 ◽  
Vol 119 (3) ◽  
pp. 1406-1419 ◽  
Author(s):  
Alexander G. Voronovich ◽  
Vladimir E. Ostashev
Keyword(s):  
Internal Waves ◽  
Low Frequency ◽  
Sound Scattering ◽  
Frequency Sound

scholarly journals Energy Transfer from High-Shear, Low-Frequency Internal Waves to High-Frequency Waves near Kaena Ridge, Hawaii

2012 ◽  
Vol 42 (9) ◽  
pp. 1524-1547 ◽  
Author(s):  
Oliver M. Sun ◽  
Robert Pinkel
Keyword(s):  
Internal Waves ◽  
High Frequency ◽  
Low Frequency ◽  
Buoyancy Frequency ◽  
Reynolds Stresses ◽  
Turbulent Dissipation ◽  
Transfer Rates ◽  
Energy Transfers ◽  
High Frequency Waves ◽  
Parametric Subharmonic Instability

Abstract Evidence is presented for the transfer of energy from low-frequency inertial–diurnal internal waves to high-frequency waves in the band between 6 cpd and the buoyancy frequency. This transfer links the most energetic waves in the spectrum, those receiving energy directly from the winds, barotropic tides, and parametric subharmonic instability, with those most directly involved in the breaking process. Transfer estimates are based on month-long records of ocean velocity and temperature obtained continuously over 80–800 m from the research platform (R/P) Floating Instrument Platform (FLIP) in the Hawaii Ocean Mixing Experiment (HOME) Nearfield (2002) and Farfield (2001) experiments, in Hawaiian waters. Triple correlations between low-frequency vertical shears and high-frequency Reynolds stresses, 〈uiw∂Ui/∂z〉, are used to estimate energy transfers. These are supported by bispectral analysis, which show significant energy transfers to pairs of waves with nearly identical frequency. Wavenumber bispectra indicate that the vertical scales of the high-frequency waves are unequal, with one wave of comparable scale to that of the low-frequency parent and the other of much longer scale. The scales of the high-frequency waves contrast with the classical pictures of induced diffusion and elastic scattering interactions and violates the scale-separation assumption of eikonal models of interaction. The possibility that the observed waves are Doppler shifted from intrinsic frequencies near f or N is explored. Peak transfer rates in the Nearfield, an energetic tidal conversion site, are on the order of 2 × 10−7 W kg−1 and are of similar magnitude to estimates of turbulent dissipation that were made near the ridge during HOME. Transfer rates in the Farfield are found to be about half the Nearfield values.

scholarly journals Variation and Episodes of Near-Inertial Internal Waves on the Continental Slope of the Southeastern East China Sea

2021 ◽  
Vol 9 (8) ◽  
pp. 916
Author(s):  
Bing Yang ◽  
Po Hu ◽  
Yijun Hou
Keyword(s):  
Continental Slope ◽  
East China Sea ◽  
Internal Waves ◽  
Low Frequency ◽  
Blue Shift ◽  
Vertical Shear ◽  
East China ◽  
Left Hand ◽  
China Sea ◽  
Generation Mechanisms

Based on in situ observations, six episodes of near-inertial internal waves (NIWs) were detected on the East China Sea (ECS) continental slope, and the mechanisms and characteristics of them were examined. The generation mechanisms of the observed NIWs included typhoon, wind burst, lateral propagation, and energy transfer from low-frequency flow. The depth-integrated near-inertial kinetic energy (NIKE) showed no significant seasonal variation, and the annual mean NIKE and near-inertial currents were 400 J/m2 and 3.50 cm/s, respectively. Downward propagation of NIKE was evident in the small wavenumber band according to the rotary vertical wavenumber spectra. The NIKE was subsurface-intensified, and the near-inertial vertical shear reached 0.01 s−1. The vertical phase speeds of the NIWs ranged from 5 to 19 m/h. The frequencies of the NIWs were mostly red-shifted, however, blue-shift also existed. One episode had both blue- and red-shifted frequencies vertically, and had both upward and downward propagating vertical phase speeds. The e-folding times of the observed NIWs ranged from 4 to 11 days, which were influenced by successive wind bursts and background vorticity. On the left-hand side of Kuroshio, the background vorticity is usually positive; however, the NIWs were almost red-shifted, which resulted from the Doppler shift of the Kuroshio.

scholarly journals Variability in the Internal Wave Field Induced by the Atlantic Deep Western Boundary Current at 16°N

2014 ◽  
Vol 44 (2) ◽  
pp. 492-516 ◽  
Author(s):  
Janna Köhler ◽  
Christian Mertens ◽  
Maren Walter ◽  
Uwe Stöber ◽  
Monika Rhein ◽  
...  
Keyword(s):  
Internal Wave ◽  
Wave Field ◽  
Continental Slope ◽  
Internal Waves ◽  
Vertical Mixing ◽  
Low Frequency ◽  
Western Boundary Current ◽  
Western Boundary ◽  
Boundary Current ◽  
Deep Western Boundary Current

Abstract Five years of continuous mooring data combined with conductivity–temperature–depth (CTD)/lowered acoustic Doppler current profiler (LADCP) measurements from five cruises are used to investigate the influence of the deep western boundary current (DWBC) on the internal wave field and associated vertical mixing at the continental slope at 16°N in the western Atlantic. The mooring data include 2-hourly rotor current-meter measurements and temperature/conductivity time series with a high temporal resolution of 5–20 min. Thus, the data resolve time scales ranging from the low-frequency variability of the large-scale DWBC that generates internal waves due to interactions with the topography to frequencies greater than that of internal waves that are associated with vertical mixing. Estimates of the vertical mixing induced by the breaking of the observed internal waves show elevated diapycnal diffusivities of up to 10−3 ± 0.4 × 10−3 m2 s−1 in the bottommost 1500 m during times of a strong DWBC (maximum velocities at the mooring site up to 50 cm s−1) whereas vertical mixing rates are about an order of magnitude lower (1.6 × 10−4 ± 0.6 × 10−4 m2 s−1) during weak flow. During periods of a strong DWBC, spectra of horizontal velocity and internal wave available potential energy change substantially at depths below 1200 m and show a strong increase in variance particularly in the near-inertial frequency band. Low-frequency, near-inertial waves generated by topography/DWBC interaction on the slope to the west of the moorings can potentially cause this observed wave intensification; ray paths estimated for these waves agree well with the observed spectral changes at different depths. Variability in the high-frequency range, considered as a proxy for turbulent mixing, is significantly correlated with the DWBC strength above the continental slope.

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