Underwater acoustic modeling and simulation

447 Pages·2003·2.856 MB·English

by  Etter, Paul C

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
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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