Underwater Acoustic Modelling and Simulation, Third Edition

447 Pages·2003·5.25 MB·English

by  Paul C. Etter

Underwater Acoustic Modeling
and Simulation
Third edition

Underwater Acoustic Modeling
and Simulation
Third edition
Paul C. Etter
Firstpublished2003
bySponPress
11NewFetterLane,LondonEC4P4EE
SimultaneouslypublishedintheUSAandCanada
bySponPress
29West35thStreet,NewYork,NY10001
This edition published in the Taylor & Francis e-Library, 2003.
SponPressisanimprintoftheTaylor&FrancisGroup
©2003PaulC.Etter
Allrightsreserved.Nopartofthisbookmaybereprintedor
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invented,includingphotocopyingandrecording,orinany
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Thepubishermakesnorepresentation,expressorimplied,with
regardtotheaccuracyoftheinformationcontainedinthisbook
andcannotacceptanylegalresponsibilityorliabilityforany
errorsoromissionsthatmaybemade.
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ISBN 0-203-41765-8 Master e-book ISBN
ISBN 0-203-41910-3 (Adobe eReader Format)
ISBN0–419–26220–2(Print Edition)
To my wife Alice and my sons Gregory and Andrew

Contents
Preface xv
Prefacetothesecondedition xvii
Prefacetothefirstedition xix
Acknowledgments xxi
1 Introduction 1
1.1 Background 1
1.1.1 Setting 1
1.1.2 Framework 2
1.2 Measurementsandprediction 4
1.3 Developmentsinmodeling 6
1.4 Advancesinsimulation 9
1.5 Operationalchallenges 10
1.5.1 Navaloperations 11
1.5.2 Offshoreindustries 13
1.5.3 Operationaloceanography 14
1.6 Inverseacousticsensingoftheoceans 15
1.7 Standarddefinitions 17
2 Acousticaloceanography 19
2.1 Background 19
2.2 Physicalandchemicalproperties 19
2.2.1 Temperaturedistribution 21
2.2.2 Salinitydistribution 22
2.2.3 Watermasses 22
2.3 Soundspeed 25
2.3.1 Calculationandmeasurements 25
2.3.2 Sound-speeddistribution 28
2.4 Boundaries 35
2.4.1 Seasurface 35
2.4.2 Icecover 38
2.4.3 Seafloor 39
viii Contents
2.5 Dynamicfeatures 43
2.5.1 Large-scalefeatures 43
2.5.2 Mesoscalefeatures 44
2.5.3 Fine-scalefeatures 54
2.6 Biologics 55
3 PropagationI:observationsandphysicalmodels 57
3.1 Background 57
3.2 Natureofmeasurements 58
3.3 Basicconcepts 59
3.4 Sea-surfaceboundary 65
3.4.1 Forwardscatteringandreflectionloss 66
3.4.2 Imageinterferenceandfrequencyeffects 67
3.4.3 Turbidityandbubbles 69
3.4.4 Iceinteraction 70
3.4.5 Measurements 72
3.5 Sea-floorboundary 72
3.5.1 Forwardscatteringandreflectionloss 73
3.5.2 Interferenceandfrequencyeffects 78
3.5.3 Attenuationbysediments 78
3.5.4 Measurements 79
3.6 Attenuationandabsorptioninseawater 80
3.7 Surfaceducts 82
3.7.1 Mixed-layerdistribution 82
3.7.2 Generalpropagationfeatures 85
3.7.3 Low-frequencycutoff 88
3.8 Deep-soundchannel 91
3.9 Convergencezones 93
3.10 Reliableacousticpath 94
3.11 Shallow-waterducts 94
3.12 Arctichalf-channel 95
3.13 Coherence 97
4 PropagationII:mathematicalmodels(PartOne) 99
4.1 Background 99
4.2 Theoreticalbasisforpropagationmodeling 100
4.2.1 Waveequation 100
4.2.2 Classificationofmodelingtechniques 102
4.3 Ray-theorymodels 103
4.3.1 Basictheory 103
4.3.2 Caustics 106
Contents ix
4.3.3 Gaussianbeamtracing 107
4.3.4 Rangedependence 107
4.3.5 Arrivalstructure 109
4.3.6 Beamdisplacement 111
4.4 Normal-modemodels 113
4.4.1 Basictheory 113
4.4.2 Normal-modesolution 114
4.4.3 Dispersioneffects 116
4.4.4 Experimentalmeasurements 117
4.4.5 Rangedependence 118
4.4.6 High-frequencyadaptations 120
4.4.7 Wedgemodes 120
4.5 Multipathexpansionmodels 121
4.6 Fast-fieldmodels 122
4.7 Parabolicequationmodels 123
4.7.1 Basictheory 124
4.7.2 Numericaltechniques 126
4.7.3 Wide-angleand3Dadaptations 129
4.7.4 Range-refractioncorrections 129
4.7.5 High-frequencyadaptations 130
4.7.6 Time-domainapplications 130
4.8 TheRAYMODEmodel–aspecificexample 131
4.9 Numericalmodelsummaries 135
5 PropagationII:mathematicalmodels(PartTwo) 152
5.1 Background 152
5.2 Surfaceductmodels 152
5.2.1 Ray-theorymodels 152
5.2.2 Wave-theorymodels 154
5.2.3 Oceanographicmixed-layermodels 155
5.3 Shallow-waterductmodels 158
5.3.1 Shallow-waterpropagationcharacteristics 158
5.3.2 Optimumfrequencyofpropagation 159
5.3.3 Numericalmodels 162
5.3.4 Empiricalmodels 167
5.4 Arcticmodels 172
5.4.1 Arcticenvironmentalmodels 172
5.4.2 Arcticpropagationmodels 172
5.4.3 Numericalmodels 173
5.4.4 Empiricalmodels 174