Introduction to the Physics and Techniques of Remote Sensing
Description
DISCOVER CUTTING EDGE THEORY AND APPLICATIONS OF MODERN REMOTE SENSING IN GEOLOGY, OCEANOGRAPHY, ATMOSPHERIC SCIENCE, IONOSPHERIC STUDIES, AND MORE
The thoroughly revised third edition of the Introduction to the Physics and Techniques of Remote Sensing delivers a comprehensive update to the authoritative textbook, offering readers new sections on radar interferometry, radar stereo, and planetary radar. It explores new techniques in imaging spectroscopy and large optics used in Earth orbiting, planetary, and astrophysics missions. It also describes remote sensing instruments on, as well as data acquired with, the most recent Earth and space missions.
Readers will benefit from the brand new and up-to-date concept examples and full-color photography, 50% of which is new to the series. You'll learn about the basic physics of wave/matter interactions, techniques of remote sensing across the electromagnetic spectrum (from ultraviolet to microwave), and the concepts behind the remote sensing techniques used today and those planned for the future.
The book also discusses the applications of remote sensing for a wide variety of earth and planetary atmosphere and surface sciences, like geology, oceanography, resource observation, atmospheric sciences, and ionospheric studies. This new edition also incorporates:
* A fulsome introduction to the nature and properties of electromagnetic waves
* An exploration of sensing solid surfaces in the visible and near infrared spectrums, as well as thermal infrared, microwave, and radio frequencies
* A treatment of ocean surface sensing, including ocean surface imaging and the mapping of ocean topography
* A discussion of the basic principles of atmospheric sensing and radiative transfer, including the radiative transfer equation
Perfect for senior undergraduate and graduate students in the field of remote sensing instrument development, data analysis, and data utilization, Introduction to the Physics and Techniques of Remote Sensing will also earn a place in the libraries of students, faculty, researchers, engineers, and practitioners in fields like aerospace, electrical engineering, and astronomy.
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Persons
CHARLES ELACHI, PHD, is a Professor of electrical engineering and planetary science at Caltech. He was the Director of NASA's Jet Propulsion Laboratory from 2001 to 2016. He played the leading role in the development of five Earth Orbiting Shuttle Imaging Radar missions and the Cassini Titan Radar mapping instrument. He taught the Physics of Remote Sensing at Caltech from 1982 to 2002.
JAKOB VAN ZYL, PHD, occupied numerous leadership positions at the Jet Propulsion Laboratory including the Radar Section, Planetary Exploration Program, Astronomy and Physics Program and as the Associate Director for advanced missions. He taught the Physics of Remote Sensing at Caltech from 2002 to 2020.
Content
Preface xv
1 Introduction 1
1.1 Types and Classes of Remote Sensing Data 1
1.2 Brief History of Remote Sensing 6
1.3 Remote Sensing Space Platforms 13
1.4 Transmission Through the Earth and Planetary Atmospheres 15
References and Further Reading 18
2 Nature and Properties of Electromagnetic Waves 19
2.1 Fundamental Properties of Electromagnetic Waves 19
2.1.1 Electromagnetic Spectrum 19
2.1.2 Maxwell's Equations 20
2.1.3 Wave Equation and Solution 21
2.1.4 Quantum Properties of Electromagnetic Radiation 21
2.1.5 Polarization 22
2.1.6 Coherency 25
2.1.7 Group and Phase Velocity 26
2.1.8 Doppler Effect 27
2.2 Nomenclature and Definition of Radiation Quantities 30
2.2.1 Radiation Quantities 30
2.2.2 Spectral Quantities 31
2.2.3 Luminous Quantities 32
2.3 Generation of Electromagnetic Radiation 32
2.4 Detection of Electromagnetic Radiation 34
2.5 Interaction of Electromagnetic Waves with Matter: Quick Overview 35
2.6 Interaction Mechanisms Throughout the Electromagnetic Spectrum 38
Exercises 42
References and Further Reading 43
3 Solid Surfaces Sensing in the Visible and Near Infrared 44
3.1 Source Spectral Characteristics 44
3.2 Wave-Surface Interaction Mechanisms 47
3.2.1 Reflection, Transmission, and Scattering 48
3.2.2 Vibrational Processes 51
3.2.3 Electronic Processes 54
3.2.4 Fluorescence 59
3.3 Signature of Solid Surface Materials 61
3.3.1 Signature of Geologic Materials 61
3.3.2 Signature of Biologic Materials 62
3.3.3 Depth of Penetration 67
3.4 Passive Imaging Sensors 70
3.4.1 Imaging Basics 70
3.4.2 Sensor Elements 71
3.4.3 Detectors 76
3.5 Types of Imaging Systems 81
3.6 Description of Some Visible/Infrared Imaging Sensors 84
3.6.1 Landsat Enhanced Thematic Mapper Plus (ETM+) 84
3.6.2 Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) 87
3.6.3 Mars Orbiter Camera (MOC) 89
3.6.4 Mars Exploration Rover Panchromatic Camera (Pancam) 90
3.6.5 Cassini Imaging Instrument 91
3.6.6 Juno Imaging System 93
3.6.7 Europa Imaging System 93
3.6.8 Cassini Visual and Infrared Mapping Spectrometer (VIMS) 94
3.6.9 Chandrayaan Imaging Spectrometer M3 95
3.6.10 Sentinel Multispectral Imager 95
3.6.11 Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) 95
3.7 Active Sensors 96
3.8 Surface Sensing at Very Short Wavelengths 97
3.8.1 Radiation Sources 98
3.8.2 Detection 98
3.9 Image Data Analysis 99
3.9.1 Detection and Delineation 100
3.9.2 Classification 107
3.9.3 Identification 110
Exercises 113
References and Further Reading 117
4 Solid-Surface Sensing: Thermal Infrared 121
4.1 Thermal Radiation Laws 121
4.1.1 Emissivity of Natural Terrain 123
4.1.2 Emissivity from the Sun and Planetary Surfaces 124
4.2 Heat Conduction Theory 126
4.3 Effect of Periodic Heating 128
4.4 Use of Thermal Emission in Surface Remote Sensing 131
4.4.1 Surface Heating by the Sun 131
4.4.2 Effect of Surface Cover 133
4.4.3 Separation of Surface Units Based on Their Thermal Signature 135
4.4.4 Example of Application in Geology 135
4.4.5 Effects of Clouds on Thermal Infrared Sensing 135
4.5 Use of Thermal Infrared Spectral Signature in Sensing 137
4.6 Thermal Infrared Sensors 141
4.6.1 Heat Capacity Mapping Radiometer 143
4.6.2 Thermal Infrared Multispectral Scanner 145
4.6.3 ASTER Thermal Infrared Imager 145
4.6.4 Spitzer Space Telescope 149
4.6.5 2001 Mars Odyssey Thermal Emission Imaging System (THEMIS) 150
4.6.6 Advanced Very High Resolution Radiometer (AVHRR) 151
Exercises 154
References and Further Reading 156
5 Solid-Surface Sensing: Microwave Emission 159
5.1 Power-Temperature Correspondence 160
5.2 Simple Microwave Radiometry Models 161
5.2.1 Effects of Polarization 163
5.2.2 Effects of the Observation Angle 163
5.2.3 Effects of the Atmosphere 164
5.2.4 Effects of Surface Roughness 164
5.3 Applications and Use in Surface Sensing 165
5.3.1 Application in Polar Ice Mapping 165
5.3.2 Application in Soil Moisture Mapping 166
5.3.3 Measurement Ambiguity 170
5.4 Description of Microwave Radiometers 170
5.4.1 Antenna and Scanning Configuration for Real-Aperture Radiometers 171
5.4.2 Synthetic Aperture Radiometers 172
5.4.3 Receiver Subsystems 177
5.4.4 Data Processing 179
5.5 Examples of Developed Radiometers 180
5.5.1 Scanning Multichannel Microwave Radiometer (SMMR) 180
5.5.2 Special Sensor Microwave Imager (SSM/I) 181
5.5.3 Tropical Rainfall Mapping Mission Microwave Imager (TMI) 183
5.5.4 AMSR-E 184
5.5.5 SMAP Radiometer 185
Exercises 185
References and Further Reading 187
6 Solid-Surface Sensing: Microwave and Radio Frequencies 190
6.1 Surface Interaction Mechanism 190
6.1.1 Surface Scattering Models 192
6.1.2 Absorption Losses and Volume Scattering 197
6.1.3 Effects of Polarization 200
6.1.4 Effects of the Frequency 202
6.1.5 Effects of the Incidence Angle 205
6.1.6 Scattering from Natural Terrain 206
6.2 Basic Principles of Radar Sensors 209
6.2.1 Antenna Beam Characteristics 209
6.2.2 Signal Properties: Spectrum 213
6.2.3 Signal Properties: Modulation 216
6.2.4 Range Measurements and Discrimination 218
6.2.5 Doppler (Velocity) Measurement and Discrimination 221
6.2.6 High-Frequency Signal Generation 222
6.3 Imaging Sensors: Real Aperture Radars 224
6.3.1 Imaging Geometry 224
6.3.2 Range Resolution 225
6.3.3 Azimuth Resolution 225
6.3.4 Radar Equation 226
6.3.5 Signal Fading 227
6.3.6 Fading Statistics 229
6.3.7 Geometric Distortion 232
6.4 Imaging Sensors: Synthetic Aperture Radars 234
6.4.1 Synthetic Array Approach 234
6.4.2 Focused vs. Unfocused SAR 235
6.4.3 Doppler Synthesis Approach 237
6.4.4 SAR Imaging Coordinate System 239
6.4.5 Ambiguities and Artifacts 240
6.4.6 Point Target Response 243
6.4.7 Correlation with Point Target Response 246
6.4.8 Advanced SAR Techniques 248
6.4.9 Description of SAR Sensors and Missions 265
6.4.10 Applications of Imaging Radars 278
6.5 Nonimaging Radar Sensors: Scatterometers 295
6.5.1 Examples of Scatterometer Instruments 295
6.5.2 Examples of Scatterometer Data 303
6.6 Nonimaging Radar Sensors: Altimeters 304
6.6.1 Examples of Altimeter Instruments 307
6.6.2 Altimeter Applications 310
6.6.3 Imaging Altimetry 312
6.6.4 Wide Swath Ocean Altimeter 314
6.7 Nonconventional Radar Sensors 317
6.8 Subsurface Sounding 317
Exercises 320
References and Further Reading 323
7 Ocean Surface Sensing 334
7.1 Physical Properties of the Ocean Surface 334
7.1.1 Tides and Currents 335
7.1.2 Surface Waves 336
7.2 Mapping of the Ocean Topography 339
7.2.1 Geoid Measurement 339
7.2.2 Surface Wave Effects 343
7.2.3 Surface Wind Effects 345
7.2.4 Dynamic Ocean Topography 345
7.2.5 Ancillary Measurements 349
7.3 Surface Wind Mapping 351
7.3.1 Observations Required 352
7.3.2 Nadir Observations 355
7.4 Ocean Surface Imaging 356
7.4.1 Radar Imaging Mechanisms 356
7.4.2 Examples of Ocean Features on Radar Images 359
7.4.3 Imaging of Sea Ice 361
7.4.4 Ocean Color Mapping 363
7.4.5 Ocean Surface Temperature Mapping 365
7.4.6 Ocean Salinity Mapping 370
Exercises 371
References and Further Reading 372
8 Basic Principles of Atmospheric Sensing and Radiative Transfer 377
8.1 Physical Properties of the Atmosphere 377
8.2 Atmospheric Composition 380
8.3 Particulates and Clouds 381
8.4 Wave Interaction Mechanisms in Planetary Atmospheres 383
8.4.1 Resonant Interactions 383
8.4.2 Spectral Line Shape 387
8.4.3 Nonresonant Absorption 389
8.4.4 Nonresonant Emission 391
8.4.5 Wave Particle Interaction, Scattering 391
8.4.6 Wave Refraction 392
8.5 Optical Thickness 392
8.6 Radiative Transfer Equation 393
8.7 Case of a Nonscattering Plane Parallel Atmosphere 395
8.8 Basic Concepts of Atmospheric Remote Sounding 396
8.8.1 Basic Concept of Temperature Sounding 397
8.8.2 Basic Concept for Composition Sounding 399
8.8.3 Basic Concept for Pressure Sounding 399
8.8.4 Basic Concept of Density Measurement 399
8.8.5 Basic Concept of Wind Measurement 399
Exercises 400
References and Further Reading 401
9 Atmospheric Remote Sensing in the Microwave Region 403
9.1 Microwave Interactions with Atmospheric Gases 403
9.2 Basic Concept of Downlooking Sensors 404
9.2.1 Temperature Sounding 406
9.2.2 Constituent Density Profile: Case of Water Vapor 408
9.3 Basic Concept for Uplooking Sensors 411
9.4 Basic Concept for Limblooking Sensors 412
9.5 Inversion Concepts 415
9.6 Basic Elements of Passive Microwave Sensors 418
9.7 Surface Pressure Sensing 420
9.8 Atmospheric Sounding by Occultation 420
9.9 Microwave Scattering by Atmospheric Particles 424
9.10 Radar Sounding of Rain 424
9.11 Radar Equation for Precipitation Measurement 427
9.12 The Tropical Rainfall Measuring Mission (TRMM) 428
9.13 Rain Cube 429
9.14 CloudSat 429
9.15 Cassini Microwave Radiometer 433
9.16 Juno Microwave Radiometer (MWR) 433
Exercises 433
References and Further Reading 434
10 Millimeter and Submillimeter Sensing of Atmospheres 440
10.1 Interaction with Atmospheric Constituents 440
10.2 Downlooking Sounding 442
10.3 Limb Sounding 444
10.4 Elements of a Millimeter Sounder 447
10.5 Submillimeter Atmospheric Sounder 453
Exercises 455
References and Further Reading 456
11 Atmospheric Remote Sensing in the Visible and Infrared 458
11.1 Interaction of Visible and Infrared Radiation with the Atmosphere 458
11.1.1 Visible and Near-Infrared Radiation 458
11.1.2 Thermal Infrared Radiation 461
11.1.3 Resonant Interactions 463
11.1.4 Effects of Scattering by Particulates 463
11.2 Downlooking Sounding 466
11.2.1 General Formulation for Emitted Radiation 466
11.2.2 Temperature Profile Sounding 467
11.2.3 Simple Case Weighting Functions 469
11.2.4 Weighting Functions for Off-Nadir Observations 470
11.2.5 Composition Profile Sounding 471
11.3 Limb Sounding 472
11.3.1 Limb Sounding by Emission 472
11.3.2 Limb Sounding by Absorption 474
11.3.3 Illustrative Example: Pressure Modulator Radiometer 474
11.3.4 Illustrative Example: Fourier Transform Spectroscopy 476
11.4 Sounding of Atmospheric Motion 479
11.4.1 Passive Techniques 479
11.4.2 Passive Imaging of Velocity Field: Helioseismology 482
11.4.3 Multi-Angle Imaging SpectroRadiometer (MISR) 484
11.4.4 Multi-Angle Imager for Aerosols (MAIA) 488
11.4.5 Active Techniques 489
11.5 Laser Measurement of Wind 489
11.6 Atmospheric Sensing at Very Short Wavelengths 490
Exercises 491
References and Further Reading 492
12 Ionospheric Sensing 497
12.1 Properties of Planetary Ionospheres 497
12.2 Wave Propagation in Ionized Media 498
12.3 Ionospheric Profile Sensing by Topside Sounding 501
12.4 Ionospheric Profile by Radio Occultation 503
Exercises 505
References and Further Reading 506
Appendix A: Use of Multiple Sensors for Surface Observations 507
Appendix B: Summary of Orbital Mechanics Relevant to Remote Sensing 511
Appendix C: Simplified Weighting Functions 521
Appendix D: Compression of a Linear FM Chirp Signal 524
Index 528
1
Introduction
Remote sensing is defined as the acquisition of information about an object without being in physical contact with it. Information is acquired by detecting and measuring changes that the object imposes on the surrounding field, be it an electromagnetic, acoustic, or potential field. This could include an electromagnetic field emitted or reflected by the object, acoustic waves reflected or perturbed by the object, or perturbations of the surrounding gravity or magnetic potential field due to the presence of the object.
The term "remote sensing" is most commonly used in connection with electromagnetic techniques of information acquisition. These techniques cover the whole electromagnetic spectrum from the low-frequency radio waves through the microwave, submillimeter, far infrared, near infrared, visible, ultraviolet, x-ray, and gamma-ray regions of the spectrum.
The advent of satellites is allowing the acquisition of global and synoptic detailed information about the planets (including the Earth) and their environments. Sensors on Earth-orbiting satellites provide information about global patterns and dynamics of clouds, surface vegetation cover and its seasonal variations, surface morphologic structures, ocean surface temperature, and near-surface wind. The rapid wide coverage capability of satellite platforms allows monitoring of rapidly changing phenomena, particularly in the atmosphere. The long duration and repetitive capability allows the observation of seasonal, annual, and longer term changes such as polar ice cover, desert expansion, solid surface motion, and subsidence and tropical deforestation. The wide-scale synoptic coverage allows the observation and study of regional and continental scale features such as plate boundaries and mountain chains.
Sensors on planetary probes (orbiters, flybys, surface stations, and rovers) are providing similar information about the planets and objects in the solar system. By now all the planets in the solar system have been visited by one or more spacecraft. The comparative study of the properties of the planets is providing new insight into the formation and evolution of the solar system.
1.1 Types and Classes of Remote Sensing Data
The type of remote sensing data acquired is dependent on the type of information being sought, as well as on the size and dynamics of the object or phenomena being studied. The different types of remote sensing data and their characteristics are summarized in Table 1.1. The corresponding sensors and their role in acquiring different types of information are illustrated in Figure 1.1.
Two-dimensional images are usually required when high-resolution spatial information is needed, such as in the case of surface cover and structural mapping (Figs. 1.2 and 1.3), or when a global synoptic view is instantaneously required, such as in the case of meteorological and weather observations (Fig. 1.4). Two-dimensional images can be acquired over wide regions of the electromagnetic spectrum (Fig. 1.5) and with a wide selection of spectral bandwidths. Imaging sensors are available in the microwave, infrared (IR), visible, and ultraviolet parts of the spectrum using electronic and photographic detectors. Images are acquired by using active illumination, such as radars or lasers; solar illumination, such as in the ultraviolet, visible, and near infrared; or emission from the surface, such as in thermal infrared, microwave emission (Fig. 1.6), and x- and gamma-rays.
Table 1.1 Types of remote sensing data.
Important type of information needed Type of sensor Examples of sensors High spatial resolution and wide coverage Imaging sensors, cameras Large-format camera (1984), Seasat imaging radar (1978), Magellan radar mapper (1989), Mars Global Surveyor Camera (1996), Mars Rover Camera (2004 and 2014), Cassini Camera (2006) High spectral resolution over limited areas or along track lines Spectrometers, spectroradiometers Shuttle multispectral imaging radiometer (1981), Hyperion (2000) Limited spectral resolution with high spatial resolution Multispectral mappers Landsat multispectral mapper and thematic mapper (1972-1999), SPOT (1986-2002), Galileo NIMS (1989) High spectral and spatial resolution Imaging spectrometer Spaceborne imaging spectrometer (1991), ASTER (1999), Hyperion (2000) High accuracy intensity measurement along line tracks or wide swath Radiometers, scatterometers Seasat (1978), ERS-1/2 (1991, 1997), NSCAT (1996), QuikSCAT (1999), SeaWinds (2002) scatterometers High accuracy intensity measurement with moderate imaging resolution and wide coverage Imaging radiometers Electronically scanned microwave radiometer (1975), SMOS (2007) High accuracy measurement of location and profile Altimeters, sounders Seasat (1978), GEOSAT (1985), TOPEX/Poseidon (1992), and Jason (2001) altimeter, Pioneer Venus orbiter radar (1979), Mars orbiter altimeter (1990) Three-dimensional topographic mapping Scanning altimeters and interferometers Shuttle Radar Topography Mission (2000) Surface displacement mapping Radar interferometer Sentinel (2012, 2016), SkyMed (2007), ALOS (2006), TANDEMX (2010), ALOS-2 (2014)Spectrometers are used to detect, measure, and chart the spectral content of the incident electromagnetic field (Figs. 1.7 and 1.8). This type of information plays a key role in identifying the chemical composition of the object being sensed, be it a planetary surface or atmosphere. In the case of atmospheric studies, the spatial aspect is less critical than the spectral aspect due to the slow spatial variation in the chemical composition. In the case of surface studies, both spatial and spectral information are essential, leading to the need for imaging spectrometers (Figs. 1.9 and 1.10). The selection of the number of spectral bands, the bandwidth of each band, the imaging spatial resolution, and the instantaneous field of view leads to trade-offs based on the object being sensed, the sensor data-handling capability, and the detector technological limits.
Figure 1.1 Diagram illustrating the different types of information sought after and the type of sensor used to acquire this information. For instance, spectral information is acquired with a spectrometer. Two-dimensional surface spatial information is acquired with an imager such as a camera. An imaging spectrometer also acquires for each pixel in the image the spectral information.
Figure 1.2 Landsat MSS visible/near IR image of the Imperial Valley area in California.
Figure 1.3 Folded mountains in the Sierra Madre region, Mexico (Landsat MSS).
Figure 1.4 Infrared image of the western hemisphere acquired from a meteorological satellite.
In a number of applications, both the spectral and spatial aspects are less important, and the information needed is contained mainly in the accurate measurement of the intensity of the electromagnetic wave over a wide spectral region. The corresponding sensors, called radiometers, are used in measuring atmospheric temperature profiles and ocean surface temperature. Imaging radiometers are used to spatially map the variation of these parameters (Fig. 1.11). In active microwave remote sensing, scatterometers are used to accurately measure the backscattered field when the surface is illuminated by a signal with a narrow spectral bandwidth (Fig. 1.12). One special type of radiometer, or scatterometer, is the polarimeter, in which the key information is embedded in the polarization state of the transmitted, reflected, or scattered wave. The polarization characteristic of reflected or scattered sunlight provides information about the physical properties of planetary atmospheres.
Figure 1.5 Multispectral satellite images of the Los Angeles basin acquired in the visible, infrared, and microwave regions of the spectrum. See color section.
Figure 1.6 Passive microwave image of Antarctic ice cover acquired with a spaceborne radiometer. The color chart corresponds to the surface brightness temperature. See color section.
In a number of applications, the information required is strongly related to the three-dimensional spatial characteristics and location of the object. In this case, stereo imagers, altimeters, and interferometric radars are used to map the surface topography (Figs. 1.13-1.16), and sounders are used to map subsurface structures (Fig. 1.17) or to map atmospheric parameters (such as temperature, composition, and pressure) as a function of altitude (Fig. 1.18).
1.2 Brief History of Remote Sensing
The early development...
