RAY STABILITY FOR BACKGROUND SOUND SPEED PROFILES WITH TRANSITION

2009 ◽  
Vol 19 (09) ◽  
pp. 2953-2964 ◽  
Author(s):  
TAMÁS BÓDAI ◽  
ALAN J. FENWICK ◽  
MARIAN WIERCIGROCH
Keyword(s):  
Sound Speed ◽  
Random Media ◽  
Sound Propagation ◽  
Deep Ocean ◽  
Gradual Transition ◽  
Nonlinearity Parameter ◽  
Ambient Sound ◽  
Eastern North Atlantic ◽  
Sound Speed Structure ◽  
Theory Framework

In this paper deep ocean sound propagation through random media is considered. The study is conducted within a ray theory framework, which facilitates the assessment of ray stability. Model ocean environments where there is a gradual transition between two ambient sound speed profiles, a single duct Munk profile and a double duct profile taken in the Eastern North Atlantic are examined. We build on the finding that the ambient sound speed structure controls ray stability [Beron-Vera & Brown, 2003], and extend this statement for sound speed profiles with transition. It is shown that launching basins, plots constructed by the Maximal Lyapunov Exponent and indicating desirable ray launching parameters, can be predicted by the unperturbed ray system using the nonlinearity parameter.

ACOUSTIC RAY STABILITY FOR LONG-RANGE SOUND SPEED PROFILE TRANSITION SCENARIOS

2011 ◽  
Vol 21 (01) ◽  
pp. 177-194 ◽  
Author(s):  
TAMÁS BÓDAI ◽  
MARIAN WIERCIGROCH
Keyword(s):  
Sound Speed ◽  
Sudden Change ◽  
Vertical Plane ◽  
Deep Ocean ◽  
Gradual Transition ◽  
Speed Profile ◽  
Sound Speed Profile ◽  
Wave Guides ◽  
Sound Speed Structure ◽  
Special Case

Range-dependency in the background sound speed structure for deep ocean propagation scenarios is typical. Here a special case is considered when there is a gradual transition between single and double minimum sound speed profiles. Ray stability, an important measure for many applications, is analyzed. It is done by studying the unperturbed autonomous ray equations in the quasistatic limit. The wave guide is mapped out in terms of constant action curves in the vertical plane of propagation, which reveals a bifurcation effect in the studied wave guides. Conditions for the constancy or a sudden change of the action of a ray trajectory, an effect that impacts on the "use" of a ray, are given.

scholarly journals Reliable Acoustic Path and Direct-Arrival Zone Spatial Gain Analysis for a Vertical Line Array

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3462 ◽  
Author(s):  
Chunyu Qiu ◽  
Shuqing Ma ◽  
Yu Chen ◽  
Zhou Meng ◽  
Jianfei Wang
Keyword(s):  
Sound Propagation ◽  
Correlation Coefficients ◽  
Deep Ocean ◽  
Vertical Line ◽  
Horizontal Line ◽  
Acoustic Path ◽  
Vertical Arrays ◽  
Peak Structure ◽  
Line Array ◽  
Propagation Properties

A method is developed in this paper to calculate the spatial gain of a vertical line array when the plane-wave assumption is not applicable and when the oceanic ambient noise is correlated. The proposed optimal array gain (OAG), which can evaluate the array’s performance and effectively guide its deployment, can be given by an equation in which the noise gain (NG) is subtracted from the signal gain (SG); hence, a high SG and a negative NG can enhance the performance of the array. OAGs and SGs with different array locations are simulated and analyzed based on the sound propagation properties of the direct-arrival zone (DAZ) and the reliable acoustic path (RAP) using ray theory. SG and NG are related to the correlation coefficients of the signals and noise, respectively, and the vertical correlation is determined by the structures of the multipath arrivals. The SG in the DAZ is always high because there is little difference between the multipath waves, while the SG in the RAP changes with the source-receiver range because of the variety of structure in the multiple arrivals. The SG under different conditions is simulated in this work. The “dual peak” structure can often be observed in the vertical directionality pattern of the noise because of the presence of bottom reflection and deep sound channel. When the directions of the signal and noise are close, the conventional beamformer will enhance the correlation of not only the signals but also the noise; thus, the directivity of the signals and noise are analyzed. Under the condition of having a typical sound speed profile, the OAG in some areas of the DAZ and RAP can achieve high values and even exceed the ideal gain of horizontal line array 10 logN dB, while, in some other areas, it will be lowered because of the influence of the NG. The proposed method of gain analysis can provide analysis methods for vertical arrays in the deep ocean under many conditions with references. The theory and simulation are tested by experimental data.

Temperature-driven seasonal and longer term changes in spatially averaged deep ocean ambient sound at frequencies 63–125 Hz

2021 ◽  
Vol 149 (4) ◽  
pp. 2531-2545
Author(s):  
Michael A. Ainslie ◽  
Rex K. Andrew ◽  
Bruce M. Howe ◽  
James A. Mercer
Keyword(s):  
Deep Ocean ◽  
Ambient Sound

Comparison of Sound Propagation Characteristic between Deep and Shallow Water

2014 ◽  
Vol 577 ◽  
pp. 1198-1201
Author(s):  
Zhang Liang ◽  
Chun Xia Meng ◽  
Hai Tao Xiao
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Sound Speed ◽  
Sound Propagation ◽  
Spherical Wave ◽  
Sound Field ◽  
Propagation Loss ◽  
Speed Profile ◽  
Sound Speed Profile ◽  
Propagation Law

The physical characteristics are compared between shallow and deep water, in physics and acoustics, respectively. There is a specific sound speed profile in deep water, which is different from which in shallow water, resulting in different sound propagation law between them. In this paper, the sound field distributions are simulated under respective typical sound speed profile. The color figures of sound intensity are obtained, in which the horizontal ordinate is distance, and the vertical ordinate is depth. Then we can get some important characteristics of sound propagation. The results show that the seabed boundary is an important influence on sound propagation in shallow water, and sound propagation loss in deep water convergent zone is visibly less than which in spherical wave spreading. We can realize the remote probing using the acoustic phenomenon.

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