An introduction to the physical principles underlying Earth remote sensing
The development of spaceborne remote sensing technology has led to a new understanding of the complexity of our planet by allowing us to observe Earth and its environments on spatial and temporal scales that are unavailable to terrestrial sensors.
Remote Sensing Physics: An Introduction to Observing Earth from Space is a graduate-level text that examines the underlying physical principles and techniques used to make remote measurements, along with the algorithms used to extract geophysical information from those measurements.
Volume highlights include:
- Basis for Earth remote sensing including ocean, land, and atmosphere
- Description of satellite orbits relevant for Earth observations
- Physics of passive sensing, including infrared, optical and microwave imagers
- Physics of active sensing, including radars and lidars
- Overview of current and future Earth observation missions
- Compendium of resources including an extensive bibliography
- Sample problem sets and answers available to instructors
The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Table of Contents:
Acronyms xiii
Preface xix
About the Companion Website xxi
1 Introduction to Remote Sensing 1
1.1 How Remote SensingWorks 4
References 9
2 Satellite Orbits 11
2.1 Computation of Elliptical Orbits 15
2.2 Low Earth Orbits 16
2.3 Geosynchronous Orbits 23
2.4 Molniya Orbit 27
2.5 Satellite Orbit Prediction 29
2.6 Satellite Orbital Trade-offs 29
References 31
3 Infrared Sensing 33
3.1 Introduction 33
3.2 Radiometry 33
3.3 Radiometric Sensor Response 37
3.3.1 Derivation 37
3.3.2 Example Sensor Response Calculations 40
3.3.3 Response of a Sensor with a Partially-Filled FOV 41
3.4 Blackbody Radiation 41
3.4.1 Planck’s Radiation Law 41
3.4.2 Microwave Blackbody 43
3.4.3 Low-Frequency and High-Frequency Limits 44
3.4.4 Stefan–Boltzmann Law 44
3.4.5 Wein’s Displacement Law 44
3.4.6 Emissivity 45
3.4.7 Equivalent Blackbody Temperature 45
3.5 IR Sea Surface Temperature 45
3.5.1 Contributors to Infrared Measurements 45
3.5.2 Correction of Low-Altitude Infrared Measurements 47
3.5.3 Correction of High-Altitude Infrared Measurements 49
3.6 Atmospheric Radiative Transfer 50
3.7 Propagation in Seawater 55
3.8 Smooth Surface Reflectance 58
3.9 Rough Surface Reflectance 61
3.10 Ocean Thermal Boundary Layer 63
3.11 Operational SST Measurements 66
3.11.1 AVHRR Instrument 67
3.11.2 AVHRR Processing 69
3.11.3 AVHRR SST Algorithms 70
3.11.4 Example AVHRR Images 71
3.11.5 VIIRS Instrument 72
3.11.6 SST Accuracy 76
3.11.7 Applications 77
3.12 Land Temperature – Theory 78
3.13 Operational Land Temperature 81
3.14 Terrestrial Evapotranspiration 86
3.15 Geologic Remote Sensing 88
3.15.1 Linear Mixture Theory and Spectral Unmixing 90
3.16 Atmospheric Sounding 92
References 96
4 Optical Sensing – Ocean Color 101
4.1 Introduction to Ocean Color 101
4.2 Fresnel Reflection 105
4.3 Skylight 108
4.4 Water-Leaving Radiance 108
4.5 Water Column Reflectance 111
4.5.1 Pure Seawater 114
4.5.2 Case 1Waters 114
4.5.3 Case 2Waters 115
4.6 Remote Sensing Reflectance 116
4.7 Ocean Color Data – Case 1Water 119
4.7.1 Other Uses of Ocean Color 120
4.8 Atmospheric Corrections 121
4.9 Ocean Color Satellite Sensors 125
4.9.1 General History 125
4.9.2 SeaWiFS 132
4.9.3 MODIS 133
4.9.4 VIIRS 136
4.10 Ocean Chlorophyll Fluorescence 139
References 145
5 Optical Sensing – Land Surfaces 149
5.1 Introduction 149
5.2 Radiation over a Lambertian Surface 149
5.3 Atmospheric Corrections 153
5.4 Scattering from Vegetation 154
5.5 Normalized Difference Vegetation Index 158
5.6 Vegetation Condition and Temperature Condition Indices 164
5.7 Vegetation Indices from Hyperspectral Data 165
5.8 Landsat Satellites 166
5.9 High-resolution EO sensors 170
5.9.1 Introduction 170
5.9.2 First Generation Systems 170
5.9.3 Second Generation Systems 172
5.9.4 Third Generation Systems 172
5.9.5 Commercial Smallsat Systems 173
References 182
6 Microwave Radiometry 185
6.1 Introduction to Microwave Radiometry 185
6.2 Microwave Radiometers 185
6.3 Microwave Radiometry 187
6.3.1 Antenna Pattern 188
6.3.2 Antenna Temperature 189
6.3.3 Examples 190
6.4 Polarization 191
6.4.1 Basic Polarization 191
6.4.2 Jones Vector 192
6.4.3 Stokes Parameters 193
6.5 Passive Microwave Sensing of the Ocean 194
6.5.1 Atmospheric Transmission 195
6.5.2 Seawater Emissivity 195
6.5.3 Fresnel Reflection Coefficients, Emissivity, and Skin Depth 196
6.5.4 Sky Radiometric Temperature 197
6.5.5 Sea Surface Brightness Temperature 199
6.5.6 Wind Direction from Polarization 202
6.6 Satellite Microwave Radiometers 203
6.6.1 SMMR 204
6.6.2 SSM/I and SSMI/S 205
6.6.3 SSM/I Wind Algorithm 207
6.6.4 AMSR-E 208
6.6.5 WindSat 210
6.7 Microwave Radiometry of Sea Ice 213
6.8 Sea Ice Measurements 219
6.9 Microwave Radiometry of Land Surfaces 224
6.10 Atmospheric Sounding 229
References 232
7 Radar 235
7.1 Radar Range Equation 235
7.2 Radar Cross-Section 239
7.3 Radar Resolution 242
7.4 Pulse Compression 246
7.5 Types of Radar 250
7.6 Example Terrestrial Radars 251
7.6.1 Weather Radars 251
7.6.2 HF SurfaceWave Radar 254
References 255
8 Altimeters 257
8.1 Introduction to Altimeters 257
8.2 Specular Scattering 260
8.3 Altimeter Wind Speed 263
8.4 Altimeter SignificantWave Height 266
8.5 Altimeter Sea Surface Height 269
8.5.1 Introduction 269
8.5.2 Pulse-limited vs Beam-limited Altimeter 269
8.5.3 Altimeter Pulse Timing Precision 270
8.5.4 Altimeter Range Corrections 270
8.6 Sea Surface Topography 274
8.7 Measuring Gravity and Bathymetry 280
8.8 Delay-Doppler Altimeter 281
References 284
9 Scatterometers 287
9.1 OceanWaves 287
9.2 Bragg Scattering 293
9.3 RCS Dependence on Wind 297
9.4 Scatterometer Algorithms 300
9.5 Fan-Beam Scatterometers 303
9.6 Conical-Scan Pencil Beam Scatterometers 306
9.7 Conical-Scan Fan-Beam Scatterometers 311
References 313
10 Synthetic Aperture Radar 315
10.1 Introduction to SAR 315
10.2 SAR Azimuth Resolution 319
10.2.1 Doppler Time History 319
10.2.2 Azimuth Extent, Integration Time, and Doppler Bandwidth 322
10.2.3 Azimuth Resolution 322
10.2.4 SAR Timing, Resolution, and Swath Limits 324
10.2.5 The Magic of SAR Exposed 325
10.3 SAR Image Formation and Image Quality 326
10.4 SAR Imaging of Moving Scatterers 329
10.5 Multimode SARs 332
10.6 Polarimetric SAR 333
10.6.1 Polarimetric Response of Canonical Targets 333
10.6.2 Decompositions 334
10.6.3 Compact Polarimetry 336
10.7 SAR Systems 337
10.7.1 Radarsat-1 339
10.7.2 Envisat 339
10.7.3 PALSAR 339
10.7.4 Radarsat-2 339
10.7.5 TerraSAR-X 339
10.7.6 COSMO-SkyMed 341
10.7.7 Sentinel-1 343
10.7.8 Radar Constellation Mission (RCM) 343
10.7.9 Military SARs 343
10.8 Advanced SARs 346
10.8.1 Cross-Track Interferometry 346
10.8.2 Along-Track Interferometry 347
10.8.3 Differential Interferometry 350
10.8.4 Tomographic Interferometry 351
10.8.5 High-Resolution, Wide-Swath SAR 351
10.9 SAR Applications 353
10.9.1 SAR Ocean SurfaceWaves 353
10.9.2 SAR Winds 359
10.9.3 SAR Bathymetry 365
10.9.4 SAR Ocean InternalWaves 371
10.9.5 SAR Sea Ice 376
10.9.6 SAR Oil Slicks and Ship Detection 378
10.9.7 SAR Land Mapping Applications and Distortions 386
10.9.8 SAR Agricultural Applications 392
References 395
11 Lidar 399
11.1 Introduction 399
11.2 Types of Lidar 399
11.2.1 Direct vs Coherent Detection 400
11.3 Processes Driving Lidar Returns 401
11.3.1 Elastic Scattering 401
11.3.2 Inelastic Scattering 402
11.3.3 Fluorescence 403
11.4 Lidar Range Equation 403
11.4.1 Point Scattering Target 403
11.4.2 Lambertian Surface 404
11.4.3 Elastic Volume Scattering 404
11.4.4 Bathymetric Lidar 404
11.5 Lidar Receiver Types 406
11.5.1 Linear (full waveform) Lidar 406
11.5.2 Single Photon Lidar 407
11.6 Lidar Altimetry 408
11.6.1 NASA Airborne Topographic Mapper 408
11.6.2 Space-Based Lidar Altimeters (IceSat-1 & 2) 409
11.6.3 Bathymetric Lidar 410
11.7 Lidar Atmospheric Sensing 410
11.7.1 ADM-Aeolus 411
11.7.2 NASA CALIOP 414
References 417
12 Other Remote Sensing and Future Missions 419
12.1 Other Types of Remote Sensing 419
12.1.1 GRACE 419
12.1.2 Limb Sounding 419
12.2 Future Missions 420
12.2.1 NASA Missions 421
12.2.2 ESA Missions 422
12.2.3 Summary 423
References 424
Appendix A Constants 425
Appendix B Definitions of Common Angles 427
Appendix C Example Radiometric Calculations 431
Appendix D Optical Sensors 437
D.1 Example Optical Sensors 439
D.1.1 Photodiodes 440
D.1.2 Charge-Coupled Devices 442
D.1.3 CMOS Image Sensors 444
D.1.4 Bolometers and Microbolometers 444
D.2 Optical Sensor Design Examples 446
D.2.1 Computing Exposure Times 446
D.2.2 Impact of Digitization and Shot Noise on Contrast Detection 448
References 449
Appendix E Radar Design Example 451
Appendix F Remote Sensing Resources on the Internet 459
F.1 Information and Tutorials 459
F.2 Data 459
F.3 Data Processing Tools 460
F.4 Satellite and Sensor Databases 460
F.5 Other 460
Appendix G Useful Trigonometric Identities 461
Index 463
About the Author :
Rick Chapman, The Johns Hopkins University Applied Physics Laboratory, USA
Richard Gasparovic, The Johns Hopkins University Applied Physics Laboratory (Ret.), USA
