Statistics of Acoustic Pulse Signals Through Nonlinear Waves on the Continental Shelf of the Northeastern China Sea

Statistics of Acoustic Pulse Signals Through Nonlinear Waves on the Continental Shelf of the Northeastern China Sea
Author:
Publisher:
Total Pages: 106
Release: 2008
Genre: Gravity waves
ISBN:

A component of the Office of Naval Research (ONR) funded Windy Islands Soliton Experiment (WISE) was conducted from 13 - 15 April 2005 on the continental shelf in the northeast portion of the South China Sea to study the effects of nonlinear internal waves on the transmission of a 400-Hz signal. To capture the ocean variability along the acoustic path, a series of environmental moorings were deployed that sampled the water column. Significant variability in the sound-speed field was observed to be induced by nonlinear internal tides with a broad (~ 10 km) horizontal scale (referred to as the "long-wave pattern ') and narrow (

Statistics of Acoustic Pulse Signals Through Nonlinear Internal Waves on the Continental Shelf of the Northeastern South China Sea

Statistics of Acoustic Pulse Signals Through Nonlinear Internal Waves on the Continental Shelf of the Northeastern South China Sea
Author:
Publisher:
Total Pages: 124
Release: 2008
Genre:
ISBN:

A component of the Office of Naval Research (ONR) funded Windy Islands Soliton Experiment (WISE) was conducted from 13 - 15 April 2005 on the continental shelf in the northeast portion of the South China Sea to study the effects of nonlinear internal waves on the transmission of a 400-Hz signal. To capture the ocean variability along the acoustic path, a series of environmental moorings were deployed that sampled the water column. Significant variability in the sound-speed field was observed to be induced by nonlinear internal tides with a broad (~ 10 km) horizontal scale (referred to as the "long-wave pattern") and narrow (

In-situ Observations of Internal Waves on the Continental Slope and Shelf of the South China Sea

In-situ Observations of Internal Waves on the Continental Slope and Shelf of the South China Sea
Author: Sommai Tharawechrak
Publisher:
Total Pages:
Release: 2007
Genre:
ISBN:

ABSTRACT: Large amplitude internal waves are a long recognized feature of the South China Sea. Remote sensing imagery often shows the sea-surface manifestation of these waves as they radiate from the Luzon passage into the deep water of the South China Sea. In situ observations have shown that the waves occur as soliton-like coherent packets, creating short wavelength depressions in the thermocline stratification. These waves are described as nonlinear, with their steepness often exceeding a slope of 1/50. In the deep basin west of Luzon, the waves are known to reach displacement amplitudes exceeding 100 m, and persist for several days as they propagate toward China and Vietnam. The packets convert to elevation anomalies as they shoal onto the continental slope, becoming stretched into longer trains of waves. Shoreward of the continental slope, there is little previous in-situ data available for use in quantifying wave energy. Here, we examine survey data from April 2005, allowing for direct assessment of waves on the continental shelf.

Modeling a 400 Hz Signal Transmission Through the South China Sea Basin

Modeling a 400 Hz Signal Transmission Through the South China Sea Basin
Author: Chris S. Bernotavicius
Publisher:
Total Pages: 37
Release: 2009
Genre: Mathematical models
ISBN:

As part of the Office of Naval Research (ONR) sponsored Windy Island Soliton Experiment (WISE), two deep water moorings were placed in the northeastern portion of the South China Sea deep basin to conduct an acoustic propagation study. For approximately one year the source and receiver transmitted and received phase-modulated signals to measure the multi-scale variability in the transmission loss induced by the ocean mesoscale variability and the progression of internal tides and waves. A numerical acoustic propagation model based on Hamiltonian ray tracing is utilized to replicate the observed basic arrival structure and transmission loss. Being able to accurately model the basic arrival structure is a necessary first step before modeling the observed variability can be attempted. The comparison of the modeled arrival structure with the actual data was utilized to refine the angular resolution of the ray fan in the model, estimate the geo-acoustic properties of the bottom, and develop transmission loss estimates. Transmission loss measurements from sono-buoy data were used as an independent metric to evaluate the model.