MEASUREMENT AND SIMULATION FOR WIND NOISES IN THE OCEAN ENVIRONMENTS WITH NONLINEAR INTERNAL WAVES

2008 ◽  
Vol 16 (02) ◽  
pp. 163-176 ◽  
Author(s):  
HSIANG-CHIH CHAN ◽  
RUEY-CHANG WEI ◽  
CHI-FANG CHEN
Keyword(s):  
Internal Waves ◽  
Sound Speed ◽  
Environmental Changes ◽  
Acoustic Noise ◽  
Propagation Model ◽  
Wind Noise ◽  
Nonlinear Internal Waves ◽  
Line Array ◽  
Noise Data ◽  
Water Temperature Data

This study obtains wind noise variations by experimental data and simulated results to describe meteorological and oceanic effects. The ambient noise data were measured by a vertical line array in the 2001 ASIAEX South China Sea experiment. An acoustic propagation model is used in noise modeling for calculating the sound pressure of noises at receiving sites, including the effects of ocean environmental changes, bottom interactions, and noise fluctuations at different depths. Both range-independent and range-dependent sound speed profiles are generated with in-situ water temperature data. Results show fluctuating noise levels with variations in ocean environments. But the fluctuations are small such that only weak correlation exists in the acoustic noise data and ocean data. Results also indicate that using range-independent sound speed profiles can simulate noise field in range-dependent ocean environments with nonlinear internal waves for shallow regions with flat bottoms.

scholarly journals Distribution and Source Sites of Nonlinear Internal Waves Northeast of Hainan Island

2022 ◽  
Vol 10 (1) ◽  
pp. 55
Author(s):  
Jianjun Liang ◽  
Xiao-Ming Li ◽  
Kaiguo Fan
Keyword(s):  
Internal Waves ◽  
Hainan Island ◽  
Luzon Strait ◽  
Satellite Observations ◽  
Propagation Model ◽  
Tidal Period ◽  
S Waves ◽  
Nonlinear Internal Waves ◽  
Type D ◽  
Good Agreement

The distribution and source sites of nonlinear internal waves (NLIWs) northeast of Hainan Island were investigated using satellite observations and a wavefront propagation model. Satellite observations show two types of NLIWs (here referred to as type-S and type-D waves). The type-S waves are spaced at a semidiurnal tidal period and the type-D waves are spaced at a diurnal tidal period. The spatial distribution of the two types of NLIWs displays a sandwich structure in which the middle region is influenced by both types of NLIWs, and the northern and southern regions are governed by the type-S and type-D waves, respectively. Solving the wavefront model yields good agreement between simulated and observed wavefronts from the Luzon Strait to Hainan Island. We conclude that the NLIWs originate from the Luzon Strait.

scholarly journals Shoaling of nonlinear internal waves in Massachusetts Bay

2008 ◽  
Vol 113 (C8) ◽  
Author(s):  
A. Scotti ◽  
R. C. Beardsley ◽  
B. Butman ◽  
J. Pineda
Keyword(s):  
Internal Waves ◽  
Massachusetts Bay ◽  
Nonlinear Internal Waves

scholarly journals Energy transformations and dissipation of nonlinear internal waves over New Jersey's continental shelf

2010 ◽  
Vol 17 (4) ◽  
pp. 345-360 ◽  
Author(s):  
E. L. Shroyer ◽  
J. N. Moum ◽  
J. D. Nash
Keyword(s):  
Continental Shelf ◽  
Internal Waves ◽  
Turbulent Mixing ◽  
Internal Tide ◽  
Flux Divergence ◽  
Wave Interactions ◽  
Nonlinear Internal Waves ◽  
Dissipative Loss ◽  
Peak Energy

Abstract. The energetics of large amplitude, high-frequency nonlinear internal waves (NLIWs) observed over the New Jersey continental shelf are summarized from ship and mooring data acquired in August 2006. NLIW energy was typically on the order of 105 Jm−1, and the wave dissipative loss was near 50 W m−1. However, wave energies (dissipations) were ~10 (~2) times greater than these values during a particular week-long period. In general, the leading waves in a packet grew in energy across the outer shelf, reached peak values near 40 km inshore of the shelf break, and then lost energy to turbulent mixing. Wave growth was attributed to the bore-like nature of the internal tide, as wave groups that exhibited larger long-term (lasting for a few hours) displacements of the pycnocline offshore typically had greater energy inshore. For ship-observed NLIWs, the average dissipative loss over the region of decay scaled with the peak energy in waves; extending this scaling to mooring data produces estimates of NLIW dissipative loss consistent with those made using the flux divergence of wave energy. The decay time scale of the NLIWs was approximately 12 h corresponding to a length scale of 35 km (O(100) wavelengths). Imposed on these larger scale energetic trends, were short, rapid exchanges associated with wave interactions and shoaling on a localized topographic rise. Both of these events resulted in the onset of shear instabilities and large energy loss to turbulent mixing.

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