Atmospheric Acoustic Remote Sensing: Principles and Applications

3588fm.pdf......Page 2
ATMOSPHERIC ACOUSTIC REMOTE SENSING......Page 3
Contents......Page 5
Preface......Page 11
Acknowledgments......Page 13
Author......Page 14
SYMBOL DEFINITION......Page 15
Appendix 4: Acoustic Travel Time Tomography......Page 0
1.1 DIRECT MEASUREMENTS AND REMOTE MEASUREMENTS......Page 20
1.2 HOW CAN MEASUREMENTS BE MADE REMOTELY?......Page 21
1.4 SOME HISTORY......Page 22
1.6 DIRECT SOUND PROPAGATION FROM A SOURCE TO A RECEIVER......Page 23
1.8 CREATING OUR OWN TARGET......Page 24
1.9 MODERN ACOUSTIC REMOTE SENSING......Page 25
1.10 APPLICATIONS......Page 26
1.11 WHERE TO FROM HERE?......Page 27
REFERENCES......Page 28
2.1 TEMPERATURE PROFILES NEAR THE SURFACE......Page 38
2.2 WIND PROFILES NEAR THE SURFACE......Page 40
2.3 RICHARDSON NUMBER......Page 43
2.4 THE PRANDTL NUMBER......Page 44
2.5 THE STRUCTURE OF TURBULENCE......Page 45
2.7 SIMILARITY RELATIONSHIPS......Page 47
2.8 PROFILES OF…......Page 49
2.10 SUMMARY......Page 50
REFERENCES......Page 52
3.1 BASICS OF SOUND WAVES......Page 53
3.2 FREQUENCY SPECTRA......Page 56
3.3 BACKGROUND AND SYSTEM NOISE......Page 58
3.4 REFLECTION AND REFRACTION......Page 60
3.5 DIFFRACTION......Page 62
3.6 DOPPLER SHIFT......Page 63
3.7.1 SCATTERING FROM TURBULENCE......Page 65
3.7.2 INTENSITY IN TERMS OF STRUCTURE FUNCTION PARAMETERS......Page 69
3.7.3 SCATTERING FROM RAIN......Page 70
3.8.2 LOSSES DUE TO ABSORPTION......Page 73
3.8.3 LOSSES DUE TO SCATTERING OUT OF THE BEAM......Page 74
3.9 SOUND PROPAGATION HORIZONTALLY......Page 77
3.10 SUMMARY......Page 78
REFERENCES......Page 79
4.1 GEOMETRIC OBJECTIVE OF SODAR DESIGN......Page 80
4.2.1 SPEAKER POLAR RESPONSE......Page 81
4.2.2 DISH ANTENNAS......Page 82
4.2.3 PHASED ARRAY ANTENNAS......Page 86
4.2.4 ANTENNA SHADING......Page 91
4.2.5 RECEIVE PHASING......Page 94
4.2.6 REFLECTORS......Page 95
4.3 MONOSTATIC AND BISTATIC SODAR SYSTEMS......Page 96
4.4 DOPPLER SHIFT FROM MONOSTATIC AND BISTATIC SODARS......Page 98
4.5 BEAM WIDTH EFFECTS ON DOPPLER SHIFT......Page 107
4.6 CONTINUOUS AND PULSED SYSTEMS......Page 108
4.7 GEOMETRY OF SCATTERING......Page 114
4.8 THE ACOUSTIC RADAR EQUATION......Page 115
4.9 ACOUSTIC BAFFLES......Page 116
4.10 FREQUENCY-DEPENDENT FORM OF THE ACOUSTIC RADAR EQUATION......Page 121
4.11 OBTAINING WIND VECTORS......Page 122
4.13 PULSE CODING METHODS......Page 125
REFERENCES......Page 128
5.1.1 SPEAKERS AND MICROPHONES......Page 130
5.1.2 HORNS......Page 133
5.1.3 PHASED-ARRAY FREQUENCY RANGE......Page 134
5.1.4 DISH DESIGN......Page 135
5.1.5 DESIGNING FOR ABSORPTION AND BACKGROUND NOISE......Page 136
5.1.6 REJECTING RAIN CLUTTER......Page 137
5.1.7 HOW MUCH POWER SHOULD BE TRANSMITTED?......Page 139
5.2.1 PULSE SHAPE, DURATION, AND REPETITION......Page 140
5.2.2 RANGE GATES......Page 142
5.3.2 MICROPHONE ARRAY......Page 145
5.3.3 LOW-NOISE AMPLIFIERS......Page 146
5.3.4 RAMP GAIN......Page 147
5.3.6 MIXING TO LOWER FREQUENCIES (DEMODULATION)......Page 148
5.3.7 SWITCHING FROM TRANSMIT TO RECEIVE, AND ANTENNA RINGING......Page 151
5.4.1 THE HIGHEST USEFUL RANGE......Page 152
5.5 LOSS OF SIGNAL IN NOISE......Page 153
5.5.1 LOSS OF SIGNAL DUE TO BEAM DRIFT......Page 157
5.6.1 WHY ARE CALIBRATIONS REQUIRED?......Page 159
5.6.2 EFFECTIVE BEAM ANGLE......Page 162
5.6.4 CALIBRATIONS AGAINST VARIOUS POTENTIAL STANDARDS......Page 163
5.6.5 THE PIE FIELD CAMPAIGN SETUP......Page 165
5.6.6 RAW SODAR DATA VERSUS MAST......Page 166
5.6.7 NUMERICAL FILTERING OF DATA......Page 168
5.6.8 CORRELATION METHOD......Page 170
5.6.9 DISTRIBUTION OF WIND SPEED DATA......Page 172
5.6.10 REGRESSION SLOPE......Page 174
5.6.11 VARIATIONS WITH HEIGHT......Page 177
5.7 SUMMARY......Page 179
REFERENCES......Page 181
6.1.2 ALIASING......Page 182
6.1.3 MIXING......Page 183
6.1.5 DYNAMIC RANGE......Page 185
6.2.2 CONSTANCY OVER SEVERAL SPECTRA......Page 187
6.2.4 SHAPE......Page 188
6.3 CONSISTENCY METHODS......Page 189
6.4 TURBULENT INTENSITIES......Page 191
6.4.1 SECOND MOMENT DATA......Page 192
6.5.2 METEK......Page 193
6.6.1 FITTING TO THE SPECTRAL PEAK......Page 195
6.6.2 ESTIMATION OF sigmaw......Page 199
6.7 AVERAGING TO IMPROVE SNR......Page 200
6.7.1 VARIANCE IN WIND SPEED AND DIRECTION OVER ONE AVERAGING PERIOD......Page 201
6.7.2 COMBINING WIND DATA FROM A NUMBER OF AVERAGING PERIODS......Page 202
6.7.3 DIFFERENT AVERAGING SCHEMES FOR SODAR AND STANDARD CUP ANEMOMETERS......Page 205
6.7.4 CALCULATING WIND COMPONENTS FROM INCOMPLETE BEAM DATA......Page 207
6.7.5 WHICH GIVES LESS UNCERTAINTY: A 3-BEAM OR A 5-BEAM SYSTEM?......Page 208
6.8 SPATIAL AND TEMPORAL SEPARATION OF SAMPLING VOLUMES......Page 210
6.9.1 HEIGHT ESTIMATION ERRORS......Page 213
6.9.2 ERRORS IN BEAM ANGLE......Page 214
6.9.5 BEAM DRIFT EFFECTS......Page 215
6.10 A MODEL FOR SODAR RESPONSE TO A PRESCRIBED ATMOSPHERE......Page 218
REFERENCES......Page 220
7.1 RADAR FUNDAMENTALS......Page 222
7.2 REFLECTION OF RADAR SIGNALS FROM SOUND WAVES......Page 223
7.3 ESTIMATION OF MEASURED HEIGHT......Page 226
7.4.1 DOPPLER-RASS......Page 227
7.4.2 BRAGG-RASS......Page 228
7.7 RASS DESIGNS......Page 229
7.8 ANTENNAS......Page 231
7.9 LIMITATIONS......Page 232
7.9.2 TEMPERATURE......Page 233
REFERENCES......Page 236
8.1.1 ENVIRONMENTAL RESEARCH......Page 237
8.1.2 BOUNDARY LAYER RESEARCH......Page 239
8.1.4 COMPLEX TERRAIN......Page 241
8.1.5 SOUND SPEED PROFILES......Page 244
8.1.6 HAZARDS......Page 246
8.2 SUMMARY......Page 247
REFERENCES......Page 248
A1.1 COMPLEX EXPONENTIALS......Page 250
A1.2 FOURIER TRANSFORMS......Page 251
A1.3 AUTOCORRELATION AND CONVOLUTION......Page 253
A1.4 LEAST-SQUARES FITTING......Page 255
Appendix 2: Sample Data Sets and Matlab Code......Page 257
A3.2.1 AQ500 SODAR......Page 258
A3.3 ATMOSPHERIC RESEARCH PTY. INC. [CANBERRA, AUSTRALIA]......Page 259
A3.5 ATMOSPHERIC SYSTEMS CORPORATION (ASC) [CALIFORNIA, USA]......Page 260
A3.6 METEK GMBH [ELMSHORN, GERMANY]......Page 261
A3.7 REMTECH SA [FRANCE]......Page 262
A3.8 SCINTEC GMBH [TÜBINGEN, GERMANY]......Page 263
Appendix 4: Acoustic Travel Time Tomography......Page 267
A5.1.1 CALIBRATION AND TESTING......Page 269
A5.1.2 OPERATING REQUIREMENTS......Page 270
A5.1.2.3 Vertical Range and Resolution......Page 271
A5.1.2.4 Reliability Criteria......Page 272
A5.1.3.1 ACOUSTIC NOISE (PASSIVE AND ACTIVE)......Page 273
A5.1.4 POWER SUPPLY AND SITE DOCUMENTATION......Page 274
A5.1.5.2 Calculation of Wind Shear......Page 275
A5.1.5.3 Measurement Period......Page 276
A5.1.6 COMPARISONS WITH MECHANICAL ANEMOMETRY......Page 277
A5.1.7 OTHER CONSIDERATIONS FOR INCORPORATING SODAR INFORMATION INTO A RESOURCE ASSESSMENT PROGRAM......Page 278
A5.2.2 INTERRELATIONS OF PARAMETERS AND CONDITIONS FOR PARAMETER VALUES......Page 280
A5.2.3 USE OF AN ARTIFICIAL SIGNAL TO VERIFY PERFORMANCE......Page 281
REFERENCES......Page 285