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
Preface xiii
Acronyms xv
1 Introduction to Remote Sensing 1
1.1 How Remote Sensing Works 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 28
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 34
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 40
3.4 Blackbody Radiation 41
3.4.1 Planck’s Radiation Law 41
3.4.2 Microwave Blackbody 42
3.4.3 Low-Frequency and High-Frequency Limits 43
3.4.4 Stefan-Boltzmann Law 43
3.4.5 Wein’s Displacement Law 44
3.4.6 Emissivity 44
3.4.7 Equivalent Blackbody Temperature 44
3.5 IR Sea Surface Temperature 45
3.5.1 Contributors to Infrared Measurements 45
3.5.2 Correction of Low-Altitude Infrared Measurements 46
3.5.3 Correction of High-Altitude Infrared Measurements 48
3.6 Atmospheric Radiative Transfer 49
3.7 Propagation in Seawater 54
3.8 Smooth Surface Reflectance 58
3.9 Rough Surface Reflectance 60
3.10 Ocean Thermal Boundary Layer 63
3.11 Operational SST Measurements 66
3.11.1 AVHRR Instrument 66
3.11.2 AVHRR Processing 68
3.11.3 AVHRR SST Algorithms 70
3.11.4 Example AVHRR Images 71
3.11.5 VIIRS Instrument 73
3.11.6 SST Accuracy 75
3.11.7 Applications 77
3.12 Land Temperature - Theory 77
3.13 Operational Land Temperature 80
3.14 Terrestrial Evapotranspiration 86
3.15 Geologic Remote Sensing 87
3.15.1 Linear Mixture Theory and Spectral Unmixing 90
3.16 Atmospheric Sounding 91
References 95
4 Optical Sensing - Ocean Color 99
4.1 Introduction to Ocean Color 99
4.2 Fresnel Reflection 103
4.3 Skylight 106
4.4 Water-Leaving Radiance 107
4.5 Water Column Reflectance 110
4.5.1 Pure Seawater 112
4.5.2 Case 1 Waters 113
4.5.3 Case 2 Waters 114
4.6 Remote Sensing Reflectance 115
4.7 Ocean Color Data - Case 1 Water 117
4.7.1 Other Uses of Ocean Color 118
4.8 Atmospheric Corrections 119
4.9 Ocean Color Satellite Sensors 124
4.9.1 General History 124
4.9.2 SeaWiFS 126
4.9.3 MODIS 130
4.9.4 VIIRS 133
4.10 Ocean Chlorophyll Fluorescence 135
References 140
5 Optical Sensing - Land Surfaces 143
5.1 Introduction 143
5.2 Radiation over a Lambertian Surface 143
5.3 Atmospheric Corrections 147
5.4 Scattering from Vegetation 147
5.5 Normalized Difference Vegetation Index 153
5.6 Vegetation Condition and Temperature Condition Indices 158
5.7 Vegetation Indices from Hyperspectral Data 159
5.8 Landsat Satellites 161
5.9 High-resolution EO sensors 164
5.9.1 Introduction 164
5.9.2 First-Generation Systems 164
5.9.3 Second-Generation Systems 168
5.9.4 Third-Generation Systems 172
5.9.5 Commercial Smallsat Systems 174
References 176
6 Microwave Radiometry 179
6.1 Introduction to Microwave Radiometry 179
6.2 Microwave Radiometers 180
6.3 Microwave Radiometry 181
6.3.1 Antenna Pattern 182
6.3.2 Antenna Temperature 184
6.3.3 Examples 185
6.4 Polarization 185
6.4.1 Basic Polarization 185
6.4.2 Jones Vector 187
6.4.3 Stokes Parameters 187
6.5 Passive Microwave Sensing of the Ocean 188
6.5.1 Atmospheric Transmission 189
6.5.2 Seawater Emissivity 189
6.5.3 Fresnel Reflection Coefficients, Emissivity, and Skin Depth 190
6.5.4 Sky Radiometric Temperature 191
6.5.5 Sea Surface Brightness Temperature 193
6.5.6 Wind Direction from Polarization 197
6.6 Satellite Microwave Radiometers 198
6.6.1 SMMR 198
6.6.2 SSM/I and SSMI/S 198
6.6.3 SSM/I Wind Algorithm 200
6.6.4 AMSR-E 203
6.6.5 WindSat 204
6.7 Microwave Radiometry of Sea Ice 207
6.8 Sea Ice Measurements 213
6.9 Microwave Radiometry of Land Surfaces 218
6.10 Atmospheric Sounding 222
References 226
7 Radar 229
7.1 Radar Range Equation 229
7.2 Radar Cross-Section 232
7.3 Radar Resolution 236
7.4 Pulse Compression 239
7.5 Types of Radar 244
7.6 Example Terrestrial Radars 245
7.6.1 Weather Radars 245
7.6.2 HF Surface Wave Radar 248
References 249
8 Altimeters 251
8.1 Introduction to Altimeters 251
8.2 Specular Scattering 254
8.3 Altimeter Wind Speed 257
8.4 Altimeter Significant Wave Height 260
8.5 Altimeter Sea Surface Height 263
8.5.1 Introduction 263
8.5.2 Pulse-limited vs Beam-limited Altimeter 263
8.5.3 Altimeter Pulse Timing Precision 264
8.5.4 Altimeter Range Corrections 264
8.6 Sea Surface Topography 268
8.7 Measuring Gravity and Bathymetry 274
8.8 Delay-Doppler Altimeter 275
References 278
9 Scatterometers 281
9.1 Ocean Waves 281
9.2 Bragg Scattering 287
9.3 RCS Dependence on Wind 291
9.4 Scatterometer Algorithms 293
9.5 Fan-Beam Scatterometers 297
9.6 Conical-Scan Pencil-Beam Scatterometers 300
9.7 Conical-Scan Fan-Beam Scatterometers 304
References 307
10 Synthetic Aperture Radar 309
10.1 Introduction to SAR 309
10.2 SAR Azimuth Resolution 313
10.2.1 Doppler Time History 313
10.2.2 Azimuth Extent, Integration Time, and Doppler Bandwidth 316
10.2.3 Azimuth Resolution 316
10.2.4 SAR Timing, Resolution, and Swath Limits 318
10.2.5 The Magic of SAR Exposed 319
10.3 SAR Image Formation and Image Quality 320
10.4 SAR Imaging of Moving Scatterers 322
10.5 Multimode SARs 325
10.6 Polarimetric SAR 326
10.6.1 Polarimetric Response of Canonical Targets 327
10.6.2 Decompositions 328
10.6.3 Compact Polarimetry 329
10.7 SAR Systems 330
10.7.1 Radarsat-1 332
10.7.2 Envisat 334
10.7.3 PALSAR 335
10.7.4 Radarsat-2 335
10.7.5 TerraSAR-X 335
10.7.6 COSMO-SkyMed 335
10.7.7 Sentinel-1 336
10.7.8 Radarsat Constellation Mission (RCM) 337
10.7.9 Military SARs 337
10.8 Advanced SARs 339
10.8.1 Cross-Track Interferometry 339
10.8.2 Along-Track Interferometry 341
10.8.3 Differential Interferometry 344
10.8.4 Tomographic Interferometry 344
10.8.5 High-Resolution, Wide-Swath SAR 344
10.9 SAR Applications 346
10.9.1 SAR Ocean Surface Waves 347
10.9.2 SAR Winds 353
10.9.3 SAR Bathymetry 360
10.9.4 SAR Ocean Internal Waves 364
10.9.5 SAR Sea Ice 370
10.9.6 SAR Oil Slicks and Ship Detection 374
10.9.7 SAR Land Mapping Applications and Distortions 380
10.9.8 SAR Agricultural Applications 386
References 388
11 Lidar 393
11.1 Introduction 393
11.2 Types of Lidar 393
11.2.1 Direct vs Coherent Detection 394
11.3 Processes Driving Lidar Returns 395
11.3.1 Elastic Scattering 395
11.3.2 Inelastic Scattering 396
11.3.3 Fluorescence 397
11.4 Lidar Range Equation 397
11.4.1 Point Scattering Target 397
11.4.2 Lambertian Surface 398
11.4.3 Elastic Volume Scattering 398
11.4.4 Bathymetric Lidar 398
11.5 Lidar Receiver Types 400
11.5.1 Linear (full waveform) Lidar 400
11.5.2 Single Photon Lidar 401
11.6 Lidar Altimetry 402
11.6.1 NASA Airborne Topographic Mapper 402
11.6.2 Space-Based Lidar Altimeters (IceSat-1 & 2) 403
11.6.3 Bathymetric Lidar 405
11.7 Lidar Atmospheric Sensing 405
11.7.1 ADM-Aeolus 405
11.7.2 NASA CALIOP 408
References 411
12 Other Remote Sensing and Future Missions 413
12.1 Other Types of Remote Sensing 413
12.1.1 GRACE 413
12.1.2 Limb Sounding 414
12.2 Future Missions 414
12.2.1 NASA Missions 415
12.2.2 ESA Missions 416
12.2.3 Summary 418
References 419
Appendix A Constants 421
Appendix B Definitions of Common Angles 423
Appendix C Example Radiometric Calculations 427
Appendix D Optical Sensors 433
D.1 Example Optical Sensors 435
D.1.1 Photodiodes 435
D.1.2 Charge-Coupled Devices 437
D.1.3 CMOS Image Sensors 439
D.1.4 Bolometers and Microbolometers 440
D.2 Optical Sensor Design Examples 442
D.2.1 Computing Exposure Times 442
D.2.2 Impact of Digitization and Shot Noise on Contrast Detection 444
References 445
Appendix E Radar Design Example 447
Appendix F Remote Sensing Resources on the Internet 455
F.1 Information and Tutorials 455
F.2 Data 455
F.3 Data Processing Tools 456
F.4 Satellite and Sensor Databases 456
F.5 Other 456
Appendix G Useful Trigonometric Identities 457
Index 459
