Atmospheric Acoustic Remote Sensing: Principles and Applications

285 Pages·2007·10.42 MB·English

by  Stuart Bradley

Atmospheric
Acoustic
Remote Sensing
© 2008 by Taylor & Francis Group, LLC
3588.indb 1 11/27/07 4:06:59 PM
ATMOSPHERIC
ACOUSTIC
REMOTE SENSING
Stuart Bradley
STUART BRADLEY
CRC Press
Taylor & Francis Group
BBooccaa RRaatotonn LLoonnddoonn NNeeww Y Yoorkrk
CCRRCC PPrreessss iiss a ann imimpprrinintt ooff t thhee
TTaayylloorr && FFrraanncciiss GGrroouupp,, aann iinnffoorrmmaa bbuussiinneessss
© 2008 by Taylor & Francis Group, LLC
3588.indb 3 11/27/07 4:06:59 PM
CRC Press
Taylor & Francis Group
6000 Broken Sound Parkway NW, Suite 300
Boca Raton, FL 33487-2742
© 2008 by Taylor & Francis Group, LLC
CRC Press is an imprint of Taylor & Francis Group, an Informa business
No claim to original U.S. Government works
Printed in the United States of America on acid-free paper
10 9 8 7 6 5 4 3 2 1
International Standard Book Number-13: 978-0-8493-3588-4 (Hardcover)
This book contains information obtained from authentic and highly regarded sources Reason-
able efforts have been made to publish reliable data and information, but the author and publisher
cannot assume responsibility for the validity of all materials or the consequences of their use. The
Authors and Publishers have attempted to trace the copyright holders of all material reproduced
in this publication and apologize to copyright holders if permission to publish in this form has not
been obtained. If any copyright material has not been acknowledged please write and let us know so
we may rectify in any future reprint
Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced,
transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or
hereafter invented, including photocopying, microfilming, and recording, or in any information
storage or retrieval system, without written permission from the publishers.
For permission to photocopy or use material electronically from this work, please access www.
copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC)
222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that
provides licenses and registration for a variety of users. For organizations that have been granted a
photocopy license by the CCC, a separate system of payment has been arranged.
Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and
are used only for identification and explanation without intent to infringe.
Library of Congress Cataloging-in-Publication Data
Bradley, Stuart.
Atmospheric acoustic remote sensing / author, Stuart Bradley.
p. cm.
Includes bibliographical references and index.
ISBN 978-0-8493-3588-4 (hardback : alk. paper)
1. Atmosphere--Remote sensing. 2. Echo sounding. I. Title.
QC871.B73 2006
551.5028’4--dc22 2007034585
Visit the Taylor & Francis Web site at
http://www.taylorandfrancis.com
and the CRC Press Web site at
http://www.crcpress.com
© 2008 by Taylor & Francis Group, LLC
3588.indb 4 11/27/07 4:07:00 PM
Contents
Preface ......................................................................................................................xi
Acknowledgments ..................................................................................................xiii
Author ......................................................................................................................xv
SymbolList ............................................................................................................xvii
Chapter 1 WhatIsAtmosphericAcousticRemoteSensing? ................................1
1.1 DirectMeasurementsandRemoteMeasurements .........................................1
1.2 HowCanMeasurementsBeMadeRemotely?................................................2
1.3 PassiveandActiveRemoteSensing ................................................................3
1.4 SomeHistory...................................................................................................3
1.5 WhyUseAcoustics? ........................................................................................4
1.6 DirectSoundPropagationfromaSourcetoaReceiver .................................4
1.7 AcousticTargets ..............................................................................................5
1.8 CreatingOurOwnTarget ...............................................................................5
1.9 ModernAcousticRemoteSensing ..................................................................6
1.10 Applications ....................................................................................................7
1.11 WheretofromHere? .......................................................................................8
References ..................................................................................................................9
Chapter 2 TheAtmosphereNeartheGround .....................................................11
2.1 TemperatureProfilesneartheSurface ..........................................................11
2.2 WindProfilesneartheSurface .....................................................................13
2.3 RichardsonNumber ......................................................................................16
2.4 ThePrandtlNumber......................................................................................17
2.5 TheStructureofTurbulence .........................................................................18
2.6 Monin-OboukhovLength .............................................................................20
2.7 SimilarityRelationships ................................................................................20
2.8 Profilesof C2 and C2
T V .................................................................................22
2.9 ProbabilityDistributionofWindSpeeds ......................................................23
2.10 Summary .......................................................................................................23
References ................................................................................................................25
Chapter 3 SoundintheAtmosphere ...................................................................27
3.1 BasicsofSoundWaves..................................................................................27
3.2 FrequencySpectra .........................................................................................30
3.3 BackgroundandSystemNoise .....................................................................32
3.4 ReflectionandRefraction ..............................................................................34
3.5 Diffraction .....................................................................................................36
3.6 DopplerShift .................................................................................................37
v
© 2008 by Taylor & Francis Group, LLC
3588.indb 5 11/27/07 4:07:09 PM
vi AtmosphericAcousticRemoteSensing
3.7 Scattering ......................................................................................................39
3.7.1 ScatteringfromTurbulence ...............................................................39
3.7.2 IntensityinTermsofStructureFunctionParameters ........................43
3.7.3 ScatteringfromRain..........................................................................44
3.8 Attenuation ....................................................................................................47
3.8.1 LossesDuetoSphericalSpreading ...................................................47
3.8.2 LossesDuetoAbsorption ..................................................................47
3.8.3 LossesDuetoScatteringoutoftheBeam .........................................48
3.9 SoundPropagationHorizontally ...................................................................51
3.10 Summary .......................................................................................................52
References ................................................................................................................53
Chapter 4 SoundTransmissionandReception ...................................................55
4.1 GeometricObjectiveofSODARDesign ......................................................55
4.2 Speakers,Horns,andAntennas ....................................................................56
4.2.1 SpeakerPolarResponse .....................................................................56
4.2.2 DishAntennas ....................................................................................57
4.2.3 PhasedArrayAntennas .....................................................................61
4.2.4 AntennaShading ................................................................................66
4.2.5 ReceivePhasing .................................................................................69
4.2.6 Reflectors ...........................................................................................70
4.3 MonostaticandBistaticSODARSystems ....................................................71
4.4 DopplerShiftfromMonostaticandBistaticSODARs .................................73
4.5 BeamWidthEffectsonDopplerShift ..........................................................82
4.6 ContinuousandPulsedSystems ...................................................................83
4.7 GeometryofScattering .................................................................................89
4.8 TheAcousticRadarEquation .......................................................................90
4.9 AcousticBaffles ............................................................................................91
4.10 Frequency-DependentFormoftheAcousticRadarEquation ......................96
4.11 ObtainingWindVectors ...............................................................................97
4.12 MultipleFrequencies ...................................................................................100
4.13 PulseCodingMethods ................................................................................100
4.14 Summary .....................................................................................................103
References ..............................................................................................................103
Chapter 5 SODARSystemsandSignalQuality ...............................................105
5.1 TransducerandAntennaCombinations ......................................................105
5.1.1 SpeakersandMicrophones ..............................................................105
5.1.2 Horns ................................................................................................108
5.1.3 Phased-ArrayFrequencyRange ......................................................109
5.1.4 DishDesign ......................................................................................110
5.1.5 DesigningforAbsorptionandBackgroundNoise ...........................111
5.1.6 RejectingRainClutter .....................................................................112
5.1.7 HowMuchPowerShouldBeTransmitted? .....................................114
© 2008 by Taylor & Francis Group, LLC
3588.indb 6 11/27/07 4:07:10 PM
Contents vii
5.2 SODARTiming ..........................................................................................115
5.2.1 PulseShape,Duration,andRepetition ............................................115
5.2.2 RangeGates .....................................................................................117
5.3 BasicHardwareUnits .................................................................................120
5.3.1 TheBasicComponentsofaSODARReceiver ................................120
5.3.2 MicrophoneArray ...........................................................................120
5.3.3 Low-NoiseAmplifiers ......................................................................121
5.3.4 RampGain .......................................................................................122
5.3.5 Filters ...............................................................................................123
5.3.6 MixingtoLowerFrequencies(Demodulation) ...............................123
5.3.7 SwitchingfromTransmittoReceive,andAntennaRinging ...........126
5.4 DataAvailability .........................................................................................127
5.4.1 TheHighestUsefulRange ...............................................................127
5.5 LossofSignalinNoise ...............................................................................128
5.5.1 LossofSignalDuetoBeamDrift ...................................................132
5.6 Calibration ...................................................................................................134
5.6.1 WhyAreCalibrationsRequired? ....................................................134
5.6.2 EffectiveBeamAngle ......................................................................137
5.6.3 WhatAccuracyIsRequired? ...........................................................138
5.6.4 CalibrationsagainstVariousPotentialStandards............................138
5.6.5 ThePIEFieldCampaignSetup .......................................................140
5.6.6 RawSODARDataversusMast .......................................................141
5.6.7 NumericalFilteringofData .............................................................143
5.6.8 CorrelationMethod ..........................................................................145
5.6.9 DistributionofWindSpeedData ....................................................147
5.6.10 RegressionSlope ..............................................................................149
5.6.11 VariationswithHeight .....................................................................152
5.6.12 WindDirectionRegressions ............................................................154
5.7 Summary .....................................................................................................154
References ..............................................................................................................156
Chapter 6 SODARSignalAnalysis ..................................................................157
6.1 SignalAcquisition .......................................................................................157
6.1.1 Sampling ..........................................................................................157
6.1.2 Aliasing ............................................................................................157
6.1.3 Mixing..............................................................................................158
6.1.4 WindowingandSignalModulation .................................................160
6.1.5 DynamicRange ...............................................................................160
6.2 DetectingSignalsinNoise ..........................................................................162
6.2.1 HeightofthePeakaboveaNoiseThreshold ...................................162
6.2.2 ConstancyoverSeveralSpectra .......................................................162
6.2.3 NotGenerallyBeingatZeroFrequency ..........................................163
6.2.4 Shape ................................................................................................163
6.2.5 ScalingwithTransmitFrequency ....................................................164
6.3 ConsistencyMethods ..................................................................................164
© 2008 by Taylor & Francis Group, LLC
3588.indb 7 11/27/07 4:07:11 PM
viii AtmosphericAcousticRemoteSensing
6.4 TurbulentIntensities ....................................................................................166
6.4.1 SecondMomentData .......................................................................167
6.5 PeakDetectionMethodsofAeroVironmentandMetek .............................168
6.5.1 AeroVironment.................................................................................168
6.5.2 Metek ...............................................................................................168
6.6 RobustEstimationofDopplerShiftfromSODARSpectra .......................170
6.6.1 FittingtotheSpectralPeak..............................................................170
6.6.2 Estimationof(cid:84) ...............................................................................174
w
6.7 AveragingtoImproveSNR .........................................................................175
6.7.1 VarianceinWindSpeedandDirectionoverOneAveraging
Period ...............................................................................................176
6.7.2 CombiningWindDatafromaNumberofAveragingPeriods ........177
6.7.3 DifferentAveragingSchemesforSODARandStandardCup
Anemometers ...................................................................................180
6.7.4 CalculatingWindComponentsfromIncompleteBeamData .........182
6.7.5 WhichGivesLessUncertainty:A3-Beamora5-Beam
System? ............................................................................................183
6.8 SpatialandTemporalSeparationofSamplingVolumes ............................185
6.9 SourcesofMeasurementError ..................................................................188
6.9.1 HeightEstimationErrors .................................................................188
6.9.2 ErrorsinBeamAngle ......................................................................189
6.9.3 Out-of-LevelErrors ..........................................................................190
6.9.4 BiasDuetoBeamSpread ................................................................190
6.9.5 BeamDriftEffects ...........................................................................190
6.10 AModelforSODARResponsetoaPrescribedAtmosphere .....................193
6.11Summary ........................................................................................................195
References ..............................................................................................................195
Chapter 7 RASSSystems ..................................................................................197
7.1 RADARFundamentals ...............................................................................197
7.2 ReflectionofRADARSignalsfromSoundWaves .....................................198
7.3 EstimationofMeasuredHeight ..................................................................201
7.4 DeductionofTemperature ..........................................................................202
7.4.1 Doppler-RASS ................................................................................202
7.4.2 Bragg-RASS.....................................................................................203
7.5 WindMeasurements ...................................................................................204
7.6 TurbulanceMeasurements ..........................................................................204
7.7 RASSDesigns .............................................................................................204
7.8 Antennas .....................................................................................................206
7.8.1 Baffles ..............................................................................................207
7.9 Limitations .................................................................................................207
7.9.1 Range ...............................................................................................208
7.9.2 Temperature .....................................................................................208
7.10 Summary .....................................................................................................211
References ..............................................................................................................211
© 2008 by Taylor & Francis Group, LLC
3588.indb 8 11/27/07 4:07:12 PM
Contents ix
Chapter 8 Applications......................................................................................213
8.1 ReviewofSelectedApplications ................................................................213
8.1.1 EnvironmentalResearch ..................................................................213
8.1.2 BoundaryLayerResearch ................................................................215
8.1.3 WindPowerandLoading ................................................................217
8.1.4 ComplexTerrain ..............................................................................217
8.1.5 SoundSpeedProfiles .......................................................................220
8.1.6 Hazards ............................................................................................222
8.2 Summary .....................................................................................................223
References ..............................................................................................................224
Appendix 1 MathematicalBackground ...............................................................227
A1.1 ComplexExponentials ................................................................................227
A1.2 FourierTransforms .....................................................................................228
A1.3 AutocorrelationandConvolution ................................................................230
A1.4 Least-squaresFitting ...................................................................................232
Appendix 2 SampleDataSetsandMatlabCode .................................................235
Appendix 3 AvailableSystems.............................................................................237
A3.1 AeroVironmentInc.[California,USA] .......................................................237
A3.2 AQSystems[Stockholm,Sweden] ..............................................................237
A3.2.1 AQ500SODAR ............................................................................237
A3.3 AtmosphericResearchPty.Inc.[Canberra,Australia] ...............................238
A3.4 AtmosphericResearchandTechnologyLLC(ART)[Hawaii,USA]
andKaijoCorporation[Tokyo,Japan] ........................................................239
A3.5 AtmosphericSystemsCorporation(ASC)[California,USA] ...................239
A3.6 METEKGmbH[Elmshorn,Germany] .......................................................240
A3.7 REMTECHSA[France] .............................................................................241
A3.8 ScintecGmbH[Tübingen,Germany] .........................................................242
Appendix 4 AcousticTravelTimeTomography ..................................................247
Appendix 5 InstallationofaSODARorRASS ...................................................249
A5.1 GuidelinesfortheUseofSodarinWindEnergyResourceAssessment ...249
A5.1.1 CalibrationandTesting ................................................................249
A5.1.2 OperatingRequirements ..............................................................250
A5.1.2.1 Temperature ..................................................................251
A5.1.2.2 Precipitation .................................................................251
A5.1.2.3 VerticalRangeandResolution .....................................251
A5.1.2.4 ReliabilityCriteria ........................................................252
© 2008 by Taylor & Francis Group, LLC
3588.indb 9 11/27/07 4:07:12 PM
x AtmosphericAcousticRemoteSensing
A5.1.3 SitingandNoise ...........................................................................253
A5.1.3.1AcousticNoise(PassiveandActive) ..............................253
A5.1.3.2 ElectronicNoise ...........................................................254
A5.1.3.3 PublicAnnoyance ........................................................254
A5.1.4 PowerSupplyandSiteDocumentation ........................................254
A5.1.5 DataCollectionandProcessing ...................................................255
A5.1.5.1 DataParametersandSampling/RecordingIntervals ...255
A5.1.5.2 CalculationofWindShear ...........................................255
A5.1.5.3 MeasurementPeriod .....................................................256
A5.1.5.4 ExclusionofPrecipitationPeriods ...............................257
A5.1.6 ComparisonswithMechanicalAnemometry ..............................257
A5.1.7 OtherConsiderationsforIncorporatingSODARInformation
intoaResourceAssessmentProgram ..........................................258
A5.2 AnalysisofTheAeroVironment4000SODARDataProcessing
Methods .......................................................................................................260
A5.2.1 Parametersettings ........................................................................260
A5.2.2 InterrelationsofParametersandConditionsforParameter
Values ...........................................................................................260
A5.2.3 UseofanArtificialSignaltoVerifyPerformance ......................261
References ..............................................................................................................265
© 2008 by Taylor & Francis Group, LLC
3588.indb 10 11/27/07 4:07:13 PM