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About this book

This book presents a comprehensive overview of hydroacoustics and describes the physical basis of acoustic processes observed in the sea. In addition, it discusses the basic concepts and provides simplified models of sound propagation and acoustic phenomena at the boundary between environments. Lastly, the book examines in detail a number of applications of ocean acoustics and methods.

The ocean is the last reserve of natural resources. It is also an essential element in the biosphere, ensuring the latter’s balance, and plays a pivotal role in the Earth’s climate system and global warming. Consequently, studying the ocean is one of humankind’s most critical scientific tasks, but penetrating its mysteries is no mean feat. Acoustics (hydroacoustics) is one of the most powerful tools for examining the water layer and beyond, since sound waves are the only type of radiation that can propagate over distances of hundreds and even thousands of kilometers in the ocean.

This unique resource appeals to specialists working in the fields of ocean and atmosphere physics, students and postgraduate students studying sea physics and oceanology, and anyone who is interested in the problems the ocean is currently facing.

Table of Contents

Frontmatter

Chapter 1. The Mathematical Model of Acoustic Processes

Abstract
Acoustics as a science studies the movements of the compressible liquid, namely oscillatory movements, which are called sound (acoustic) waves. An acoustic wave is an alternating compression and rarefaction of the medium through which it propagates. The main local characteristics of acoustic waves are determined by such properties of the medium as temperature, pressure and concentration of impurities. The global properties of the propagation of these waves depend on the spatial and temporal distributions of the above factors, as well as on the shape of the medium boundaries, if any.
Anatoly Kistovich, Konstantin Pokazeev, Tatiana Chaplina

Chapter 2. Acoustic Phenomena in the Language of Elasticity Theory

Abstract
Let’s now turn to the second approach, in the framework of which the physical essence of acoustic phenomena, consisting in the spatio-temporal change of compressions and depressions, is directly related to the manifestation of elastic properties of the medium.
Anatoly Kistovich, Konstantin Pokazeev, Tatiana Chaplina

Chapter 3. General Properties and Character Types of Sound Waves

Abstract
In the previous sections, it was shown that sound is alternating in the space and time of compression and rarefaction of the environment in which it is distributed.
Anatoly Kistovich, Konstantin Pokazeev, Tatiana Chaplina

Chapter 4. Plane Sound Waves

Abstract
Plane waves are both an independent type of sound wave and a tool used in the study of the characteristics of wave processes of the most general type. By its structure, the plane wave is probably the simplest wave object. The most general description of this wave can be given as follows.
Anatoly Kistovich, Konstantin Pokazeev, Tatiana Chaplina

Chapter 5. Geometric Acoustics

Abstract
All previous studies have been allowed to obtain constructive results when considering a certain type of sound wave (plane, spherical, or cylindrical). In reality, arbitrary sound waves do not possess the properties of the above types, and their consideration is more difficult. At the same time, there are situations when in the local area of space the sound wave is similar to a plane wave, and in each area, the length of which is comparable with the wavelength, the wave can be roughly considered plane.
Anatoly Kistovich, Konstantin Pokazeev, Tatiana Chaplina

Chapter 6. Ray Description of the Sound Field in Inhomogeneous Media

Abstract
The ray approach to sound phenomena developed in the previous section, together with the imaginary source method described in Chap. 4, is applicable to the problem of field representation in a liquid layer.
Anatoly Kistovich, Konstantin Pokazeev, Tatiana Chaplina

Chapter 7. Wave Description of the Sound Field in Inhomogeneous Media

Abstract
The ray description of sound phenomena contains inevitable approximations that do not allow to describe acoustic processes adequately in certain cases, especially when it is necessary to reveal important subtle characteristics of the sound field, for example, near caustic surfaces. An alternative to the ray approach is the wave description.
Anatoly Kistovich, Konstantin Pokazeev, Tatiana Chaplina

Chapter 8. Sound Wave Reflection from the Ocean Floor

Abstract
Let’s now move on to the study of reflection processes from the ocean floor.
Anatoly Kistovich, Konstantin Pokazeev, Tatiana Chaplina

Chapter 9. Scattering of the Sound by Surface and Ocean Floor Irregularities

Abstract
So far, the problems of sound propagation in the ocean have been considered on the assumption that the surface and bottom were planes. In reality, both the bottom and the free surface are statistically uneven surfaces. In general, it is impossible to solve the problem of sound wave propagation for any free surface or bottom relief—boundary value problems are set on surfaces that do not allow the integration of equations with boundary conditions.
Anatoly Kistovich, Konstantin Pokazeev, Tatiana Chaplina

Backmatter

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