Influences Analysis of Environmental Parameters on Sound Propagation in Shallow Water

2014 ◽  
Vol 556-562 ◽  
pp. 4815-4819
Author(s):  
Shahabuddin Shaikh ◽  
Yi Wang Huang
Keyword(s):  
Shallow Water ◽  
Sound Speed ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Water Environment ◽  
Environmental Parameters ◽  
Sea Surface ◽  
Water Medium ◽  
Sea Bottom ◽  
Shallow Water Environment

The objectives of this paper are to analyze the effectiveness of parameters on sound propagation in a shallow-water environment. The procedure for calculation of transmission loss is only the method to analyze the influence of environmental parameters. The normal mode approach is carried out for the calculation of transmission loss. And it is conducted in the range independent environment Transmission loss for sound propagation in shallow water depends upon many natural variables such as sea surface, water medium, and sea bottom. Analyses are finalized on the results obtained by considering two types of sound channels. The results indicated that acoustic transmission loss in a shallow-water environment is dependent on the source & receiver depths, sea surface, sound speed profile (SSP) in water, sound speed in bottom, density of water & bottom, propagation range and frequency. It is necessary to mention that better transmission was found during the sound velocity increases with depth; whereas the poor transmission occurred in negative gradient channel.

Simulation for Range Prediction of Active Sonar in Shallow Water

2013 ◽  
Vol 385-386 ◽  
pp. 514-517 ◽  
Author(s):  
Liang Zhang ◽  
Chun Xia Meng ◽  
Jian Na
Keyword(s):  
Shallow Water ◽  
Sound Speed ◽  
Sound Absorption ◽  
Sound Propagation ◽  
Propagation Characteristic ◽  
Water Medium ◽  
Speed Profile ◽  
Long Distance ◽  
Sound Speed Profile ◽  
Active Sonar

In shallow water the acoustic wave from ambient noise sources carries a large number of environment information based on the complicated reflection both on the surface and seabed interface. The sound speed profile is one of the influencing factors of sound propagation characteristic, while for a long distance the sound absorption coefficient of water medium has an important significance to propagation range. The simulation results show that in shallow water sound absorption of seabed, sound speed profile and sound absorption of water were taken into account, then range prediction of active sonar can be exactly obtained using normal-mode propagation.

scholarly journals First Record of a Fos Sil Chiton (Polyplacophora) from the Bohemian Cretaceous Basin (Late Cretaceous)

2014 ◽  
Vol 47 (1-2) ◽  
pp. 27-32
Author(s):  
Jaroslav Marek ◽  
Martin Košt'ák ◽  
Martin Mazuch ◽  
Oldřich Karoušek
Keyword(s):  
Shallow Water ◽  
Late Cretaceous ◽  
Water Environment ◽  
First Record ◽  
Living Conditions ◽  
Dorsal Part ◽  
Sea Bottom ◽  
Shallow Water Environment ◽  
Bohemian Cretaceous Basin ◽  
The Town

Abstract The first record of a chiton (Polyplacophora) from the Bohemian Cretaceous Basin (Late Creta-ceous) is described herein. It comes from the working quarry of Plaňany, located near the town Kolín. Excavated deposits are of the late Cenomanian - early Turonian. The poorly preserved specimen consists of a tail valve remain and two intermediate valves, it is associated herein only with order level - i.e. Le-pidopleurida Thiele, 1910. The state of its preservation shows signs of corrosion of dorsal part caused probably by biologic digestion (in stomach) and/or, more probably, by long exposure at the sea bottom. Stratigraphically, the layer yielding chiton shell is referred to be the late Cenomanian in age. The chiton living conditions are interpreted as very shallow water environment (not exceeding 20m) with irregular rocky basement possessing numerous caves and crevices.

scholarly journals The Effects of Bubble Scattering on Sound Propagation in Shallow Water

2021 ◽  
Vol 9 (12) ◽  
pp. 1441
Author(s):  
Ruoyun Liu ◽  
Zhenglin Li
Keyword(s):  
Energy Loss ◽  
Shallow Water ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Sound Field ◽  
Sea Surface ◽  
Statistical Characteristics ◽  
Strong Wind ◽  
Scattering Attenuation ◽  
Bubble Layer

As sea waves break, a bubble layer forms beneath the sea surface. The bubble scattering affects sound propagation, thus influencing the accuracy of sound field prediction. This paper aims to investigate the effects of bubble scattering on the statistical characteristics of the sound field, the distribution of transmission loss (TL), and the average scattering attenuation in shallow water. A bubble layer model based on the bubble spectrum and a parallel Parabolic Equation (PE) model are combined to calculate and analyse the sound field in the marine environment with bubbles. The effects of the bubble layer are then compared with those of the fluctuant sea surface. The results show that the bubble scattering causes additional energy loss and random fluctuations of the sound field. The TL distribution properties and the average scattering attenuation are related to the wind speed, range, frequency, and source position relative to the negative gradient sound speed layer in shallow water. The comparison demonstrates that the random variation caused by the fluctuation of the sea surface is more significant than that caused by bubbles, and the energy loss caused by bubble scattering is more significant than the fluctuant sea surface under strong wind conditions.

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