Underwater Acoustic Modeling and Simulation, Fourth Edition

521 Pages·2013·13.21 MB·English

by  Paul C. Etter

Electrical Engineering Etter
F O U R T H E D I T I O N
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UNDERWATER ACOUSTIC D
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MODELING and SIMULATION R
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FOURTH EDITION A SSIIMMUULLAATTIIOONN
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“This is a comprehensive review of models used in underwater acoustics. It is
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fully up to date, but also provides information about older models (which are

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often still used in legacy applications). Even with the Internet and search engines
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at our fingertips, this is a book that should be on every underwater acoustic
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model–user's bookshelf, or in the next office.”
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—Dale D. Ellis, DRDC Atlantic F
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“Etter has produced a very timely update to a whole raft of topics. … The UT
chapter Special Applications and Inverse Techniques I find most interesting, as RIC
this introduces the theme of underwater acoustics modeling and simulation to T
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potentially completely new audiences. … Etter discusses complex topics by M

providing clear, well-researched explanations that are based whenever possible EO
on real-world data and which are always insightful. … a ‘must-have’ addition D
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to anyone’s bookshelf.” I
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—Peter Ward, Kongsberg Maritime Ltd. IL
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This fourth edition of a bestseller continues to provide the most authoritative NN
overview of currently available propagation, noise, reverberation, and G
sonar-performance models. It discusses the fundamental processes involved
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in simulating the performance of underwater acoustic systems and empha- n
sizes the importance of applying the proper modeling resources to simulate d

the behavior of sound in virtual ocean environments. This edition addresses S
recent advances in inverse techniques and marine-mammal protection, I
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provides updated and expanded inventories of available models, and
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includes problem sets in each chapter.
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K16072

ISBN: 978-1-4665-6493-0
90000
Paul C. Etter
9 781466 564930

F O U RT H E D I T I O N
UNDERWATER
ACOUSTIC MODELING

SIMULATION
and

F O U RT H E D I T I O N
UNDERWATER
ACOUSTIC MODELING

SIMULATION
and
Paul C. Etter
Boca Raton London New York
CRC Press is an imprint of the
Taylor & Francis Group, an informa business
CRC Press
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© 2013 by Taylor & Francis Group, LLC
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Version Date: 20130126
International Standard Book Number-13: 978-1-4665-6494-7 (eBook - PDF)
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To my wife, Alice
and to my two sons and their families:
Gregory, Sophia, Elaina, and Renae
and
Andrew and Michelle

Contents
Preface......................................................................................................................xv
Preface to the Third Edition ..................................................................................xvii
Preface to the Second Edition .................................................................................xix
Preface to the First Edition .....................................................................................xxi
Acknowledgments ................................................................................................xxiii
Author ....................................................................................................................xxv
Chapter 1 Introduction ..........................................................................................1
1.1 Background ................................................................................1
1.1.1 Setting ..........................................................................1
1.1.2 Framework ....................................................................2
1.2 Measurements and Prediction ...................................................4
1.3 Developments in Modeling ........................................................8
1.4 Advances in Simulation ...........................................................10
1.5 Operational Challenges ...........................................................11
1.5.1 Naval Operations ........................................................12
1.5.2 Offshore Industries .....................................................14
1.5.3 Operational Oceanography ........................................16
1.6 Inverse Acoustic Sensing of the Oceans..................................16
1.7 Standard Definitions ................................................................19
Chapter 2 Acoustical Oceanography ..................................................................21
2.1 Background ..............................................................................21
2.2 Physical and Chemical Properties ...........................................21
2.2.1 Temperature Distribution ...........................................23
2.2.2 Salinity Distribution ...................................................23
2.2.3 Water Masses ..............................................................25
2.3 Sound Speed ............................................................................27
2.3.1 Calculation and Measurements ..................................27
2.3.2 Sound-Speed Distribution ..........................................30
2.4 Boundaries ...............................................................................35
2.4.1 Sea Surface .................................................................35
2.4.2 Ice Cover.....................................................................41
2.4.3 Sea Floor ....................................................................42
2.5 Dynamic Features....................................................................45
2.5.1 Large-Scale Features ..................................................45
2.5.2 Mesoscale Features ....................................................46
2.5.2.1 Fronts and Eddies .......................................47
2.5.2.2 Internal Waves ............................................54
vii
viii Contents
2.5.3 Fine-Scale Features ....................................................56
2.5.3.1 Thermohaline Staircases ............................56
2.5.3.2 Langmuir Circulation .................................58
2.6 Biologics ..................................................................................60
Chapter 3 Propagation I: Observations and Physical Models .............................61
3.1 Background ..............................................................................61
3.2 Nature of Measurements .........................................................62
3.3 Basic Concepts ........................................................................63
3.4 Sea-Surface Boundary .............................................................69
3.4.1 Forward Scattering and Reflection Loss ....................69
3.4.2 Image Interference and Frequency Effects ................70
3.4.3 Turbidity and Bubbles ................................................72
3.4.3.1 Open Ocean ................................................72
3.4.3.2 Coastal Ocean .............................................73
3.4.4 Ice Interaction .............................................................74
3.4.5 Measurements .............................................................75
3.5 Sea-Floor Boundary ................................................................76
3.5.1 Forward Scattering and Reflection Loss ....................77
3.5.1.1 Acoustic Interaction with the Sea Floor .....77
3.5.1.2 Boundary Conditions and Modeling ..........77
3.5.1.3 Geoacoustic Models ....................................79
3.5.2 Interference and Frequency Effects ...........................81
3.5.3 Attenuation by Sediments ..........................................81
3.5.4 Measurements .............................................................82
3.6 Attenuation and Absorption in Sea Water ...............................83
3.7 Surface Ducts ..........................................................................86
3.7.1 Mixed-Layer Distribution...........................................86
3.7.2 General Propagation Features ....................................90
3.7.3 Low-Frequency Cutoff ...............................................95
3.8 Deep Sound Channel ...............................................................96
3.9 Convergence Zones .................................................................97
3.10 Reliable Acoustic Path .............................................................98
3.11 Shallow-Water Ducts ...............................................................98
3.12 Arctic Half-Channel ..............................................................100
3.13 Coherence ..............................................................................102
Chapter 4 Propagation II: Mathematical Models (Part One) ............................103
4.1 Background ............................................................................103
4.2 Theoretical Basis for Propagation Modeling .........................104
4.2.1 Wave Equation ..........................................................104
4.2.2 Classification of Modeling Techniques ....................106
4.3 Ray-Theory Models ...............................................................107
4.3.1 Basic Theory ............................................................107
4.3.2 Caustics ....................................................................110