scholarly journals High-frequency internal waves and thick bottom mixed layers observed by gliders in the Gulf Stream

2017 ◽  
Vol 44 (12) ◽  
pp. 6316-6325 ◽  
Author(s):  
Robert E. Todd
Keyword(s):  
Internal Waves ◽  
Gulf Stream ◽  
High Frequency ◽  
Mixed Layers

scholarly journals High-frequency internal waves near the Luzon Strait observed by underwater gliders

2013 ◽  
Vol 118 (2) ◽  
pp. 774-784 ◽  
Author(s):  
Daniel L. Rudnick ◽  
T. M. Shaun Johnston ◽  
Jeffrey T. Sherman
Keyword(s):  
Internal Waves ◽  
High Frequency ◽  
Luzon Strait ◽  
Underwater Gliders

Wavenumber transport: scattering of small-scale internal waves by large-scale wavepackets

1995 ◽  
Vol 289 ◽  
pp. 379-405 ◽  
Author(s):  
David L. Bruhwiler ◽  
Tasso J. Kaper
Keyword(s):  
Internal Waves ◽  
High Frequency ◽  
Large Scale ◽  
Wave Interaction ◽  
Initial Distribution ◽  
Small Scale ◽  
Theoretic Model ◽  
Frequency Interval ◽  
Crossing Theory ◽  
Invariance Theory

In this work, we treat the problem of small-scale, small-amplitude, internal waves interacting nonlinearly with a vigorous, large-scale, undulating shear. The amplitude of the background shear can be arbitrarily large, with a general profile, but our analysis requires that the amplitude vary on a length scale longer than the wavelength of the undulations. In order to illustrate the method, we consider the ray-theoretic model due to Broutman & Young (1986) of high-frequency oceanic internal waves that trap and detrap in a near-inertial wavepacket as a prototype problem. The near-inertial wavepacket tends to transport the high-frequency test waves from larger to smaller wavenumber, and hence to higher frequency. We identify the essential physical mechanisms of this wavenumber transport, and we quantify it. We also show that, for an initial ensemble of test waves with frequencies between the inertial and buoyancy frequencies and in which the number of test waves per frequency interval is proportional to the inverse square of the frequency, a single nonlinear wave–wave interaction fundamentally alters this initial distribution. After the interaction, the slope on a log-log plot is nearly flat, whereas initially it was -2. Our analysis captures this change in slope. The main techniques employed are classical adiabatic invariance theory and adiabatic separatrix crossing theory.

Exposure of internal waves on the sea surface

2009 ◽  
Vol 626 ◽  
pp. 1-20 ◽  
Author(s):  
HWUNG-HWENG HWUNG ◽  
RAY-YENG YANG ◽  
IGOR V. SHUGAN
Keyword(s):  
Surface Wave ◽  
Internal Wave ◽  
Surface Waves ◽  
Internal Waves ◽  
High Frequency ◽  
Numerical Solutions ◽  
Wave Excitation ◽  
Resonance Frequencies ◽  
The Impact ◽  
Current Zone

We theoretically analyse the impact of subsurface currents induced by internal waves on nonlinear Stokes surface waves. We present analytical and numerical solutions of the modulation equations under conditions that are close to group velocity resonance. Our results show that smoothing of the downcurrent surface waves is accompanied by a relatively high-frequency modulation, while the profile of the opposing current is reproduced by the surface wave's envelope. We confirm the possibility of generating an internal wave forerunner that is a modulated surface wave packet. Long surface waves can create such a wave modulation forerunner ahead of the internal wave, while other relatively short surface waves comprise the trace of the internal wave itself. Modulation of surface waves by a periodic internal wavetrain may exhibit a characteristic period that is less than the internal wave period. This period can be non-uniform while the wave crosses the current zone. Our results confirm that surface wave excitation by means of internal waves, as observed at their group resonance frequencies, is efficient only in the context of opposing currents.

ACOUSTIC TRAVEL-TIME PERTURBATIONS DUE TO SHALLOW-WATER INTERNAL WAVES IN THE YELLOW SEA

2014 ◽  
Vol 22 (01) ◽  
pp. 1440003
Author(s):  
FAN LI ◽  
XINYI GUO ◽  
TAO HU ◽  
LI MA
Keyword(s):  
Internal Wave ◽  
Shallow Water ◽  
Travel Time ◽  
Internal Waves ◽  
Yellow Sea ◽  
High Frequency ◽  
Simple Relation ◽  
Ocean Dynamics ◽  
The Yellow Sea ◽  
Acoustic Travel Time

Internal waves in shallow-water cause variations in sound speed profiles and lead to acoustic travel-time perturbations. In summer 2007, a combined acoustics/physical oceanography experiment was performed to study both the acoustical properties and the ocean dynamics of the Yellow Sea. The internal waves were recorded by the thermistor arrays. The receiving hydrophone array is enabled to monitor the acoustic travel-time fluctuations over the internal wave activities. It is shown that the activity of high frequency internal waves (having 3–6 min period) dominated the travel time perturbation. In this paper, we compare the data of high frequency internal wave with acoustic travel-time perturbation data and analyze the correlation between them. A simple relation between the modal travel-time perturbation and the displacement of the thermocline is developed which might be useful for monitoring purposes.

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