Preface
Contents
Acronyms
Part I: GNSS Theory and Delays
Chapter 1: Introduction to GNSS
1.1 GNSS History
1.1.1 GPS
1.1.2 GLONASS
1.1.3 GALILEO
1.1.4 Beidou/COMPASS
1.1.5 Other Regional Systems
1.2 GNSS Systems and Signals
1.2.1 GNSS Segments
1.2.1.1 Space Segment
1.2.1.2 Control Segment
1.2.1.3 User Segment
1.2.1.4 Augmentation Segment
1.2.2 GNSS Signals
1.3 GNSS Theory and Errors
1.3.1 GNSS Principle
1.3.2 GNSS Error Sources
1.4 GNSS Observations and Applications
1.4.1 GNSS Observation Network
1.4.2 GNSS Applications
1.4.2.1 Positioning, Navigation and Timing
1.4.2.2 GNSS Remote Sensing
References
Chapter 2: GNSS Atmospheric and Multipath Delays
2.1 Atmospheric Refractivity
2.2 GNSS Atmospheric Delays
2.2.1 Neutral Atmospheric Delays
2.2.2 Empirical Tropospheric Models
2.2.2.1 Modified Saastamoinen Model
2.2.2.2 Modified Hopfield Model
2.3 GNSS Ionospheric Delay
2.3.1 The Ionosphere
2.3.2 GNSS Ionospheric Delay
2.3.3 Empirical Ionospheric Models
2.3.3.1 Bent Model
2.3.3.2 IRI Model
2.3.3.3 Klobuchar Model
2.4 GNSS Multipath Delay
2.4.1 Multipath Effects
2.4.2 Multipath Variations
2.4.2.1 Multipath Variations with Elevation Angle
2.4.2.2 Multipath Variations with Antenna Height
2.4.3 Surface Reflection Characteristics
References
Part II: GNSS Atmospheric Sensing and Applications
Chapter 3: Ground GNSS Atmospheric Sensing
3.1 Introduction
3.2 Theory and Methods
3.2.1 Estimates of GNSS ZTD
3.2.1.1 Double Difference
3.2.1.2 Non-difference Observation
3.2.2 Mapping Functions
3.2.2.1 Herring Mapping Function
3.2.2.2 Niell Mapping Function
3.2.2.3 Vienna Mapping Functions 1 (VMF1)
3.2.2.4 Global Mapping Function
3.3 ZTD Estimate and Variations
3.3.1 ZTD Estimates from IGS Observations
3.3.2 Multi-Scale ZTD Variations
3.3.2.1 Secular ZTD Variations
3.3.2.2 Seasonal ZTD Variations
3.3.2.3 Diurnal and Semidiurnal ZTD Cycles
3.4 GNSS Precipitable Water Vapor
3.4.1 GNSS PWV Estimate
3.4.2 Comparison with Independent Observations
3.4.3 Mean PWV Characteristics
3.4.4 Seasonal PWV Variations
3.4.5 Diurnal PWV Variations
3.5 3-D Water Vapor Topography
3.6 Summary
References
Chapter 4: Ground GNSS Ionosphere Sounding
4.1 History
4.2 GNSS Ionospheric Sounding
4.2.1 DCB Determination
4.2.1.1 Test Results of Multi-stations
4.2.1.2 Test Results of Single Station
4.2.2 TEC Estimate
4.3 2-D Ionopspheric Mapping
4.3.1 Method of 2-D Ionospheric Mapping
4.3.1.1 Surface Fitting Method
4.3.1.2 Distance-Weighted Method
4.3.1.3 Hardy Function Interpolation (HFI) Method
4.3.1.4 Spherical Harmonics Functions
4.3.1.5 Triangular Grid Method
4.3.2 Applications of 2-D GNSS TEC
4.3.2.1 TEC Climatology
4.3.2.2 TEC Responses to Solar Flare and Storms
4.3.2.3 TEC Disturbances Following Earthquakes
4.4 3-D GNSS Ionospheric Mapping
4.4.1 3-D Ionospheric Topography
4.4.2 Validation of GNSS Ionospheric Tomography
4.4.3 Assessment of IRI-2001 Using GNSS Tomography
4.4.4 Ionospheric Slab Thickness
4.4.5 3-D ionospheric Behaviours to Storms
4.4.5.1 Geomagnetic Conditions
4.4.5.2 Disturbance of F2-Layer Parameters
References
Chapter 5: Theory of GNSS Radio Occultation
5.1 Introduction
5.1.1 Radio Occultation in Planetary Sciences
5.1.2 GNSS Radio Occultation in Earth Sciences
5.2 Principle of GNSS Radio Occultation
5.2.1 Atmospheric Refraction
5.2.2 Geometric Optics Approximation
5.2.3 Spherically Symmetric Atmosphere Assumption
5.2.4 Bending Angle and Refractive Index
5.3 GNSS Radio Occultation Processing
5.3.1 Calibrating and Extracting GNSS RO Observables
5.3.1.1 Precision Orbit Determination (POD) Method
5.3.1.2 Differencing Technique to Remove Clock Errors
5.3.2 Bending Angle Retrieval
5.3.2.1 Geometric Optics Method
5.3.2.2 Radio-Holographic (RH) Method
5.3.3 Ionosphere Retrieval
5.3.4 Neutral Atmosphere Retrieval
5.3.4.1 Ionospheric Calibration on Bending
5.3.4.2 Refractivity Retrieval from Abel Inversion
5.3.4.3 Quality Control
References
Chapter 6: Atmospheric Sensing Using GNSS RO
6.1 GNSS RO Atmospheric Sounding
6.1.1 Parameters Retrieval from GNSS RO
6.1.2 Dry Atmosphere Retrieval (Density, Pressure and Temperature)
6.1.3 Moist Atmosphere Retrieval
6.1.4 1D-Var (Variational Method)
6.2 Characteristics of GNSS RO Observations
6.2.1 Spatial Resolution (Vertical and Horizontal Resolution)
6.2.2 Accuracy and Precision Analysis
6.2.3 Measurement Errors
6.2.3.1 Thermal Noise
6.2.3.2 Clock Instability
6.2.3.3 Local Multipath
6.2.3.4 Receiver Tracking (Open Loop vs. Close Loop)
6.2.4 Calibration Errors
6.2.5 Retrieval Errors
6.2.5.1 Upper Boundary Condition
6.2.5.2 Spherically Symmetric Atmosphere Assumption
6.2.5.3 Atmospheric Multipath
6.2.5.4 Ducting (or Super-Refraction)
6.2.5.5 Refractivity Constant Uncertainty
6.2.5.6 Water Vapor Ambiguity
6.2.6 Experimental Validation of RO Accuracy and Precision
6.3 Dynamic Processes Studies with GNSS RO
6.3.1 Tropopause and Stratospheric Waves
6.3.2 Tropical Tidal Waves
6.3.3 Weather Front
6.3.4 Tropical Cyclones (TC)
6.3.5 Atmospheric Boundary Layer (ABL)
6.4 Weather Prediction Applications
6.4.1 GNSS RO Data Assimilation
6.4.2 Operational Assimilation of GNSS RO in NWP Models
6.5 Climate Applications
6.6 Future Application of Radio Occultation
6.6.1 Future GNSS and GNSS RO Missions
6.6.2 Airborne and Mountain-Top GNSS RO
6.6.3 LEO-to-LEO Occultation
References
Chapter 7: Ionospheric Sounding Using GNSS-RO
7.1 Introduction
7.2 Ionospheric Inversion
7.2.1 Ionosphere Inversion Based on Doppler
7.2.2 Ionosphere Inversion Based on TEC
7.2.3 Recursive Inversion of TEC
7.2.4 Amplitude Inversion
7.3 Error Analysis
7.3.1 Measurement Errors
7.3.1.1 Carrier Phase Measuring Errors
7.3.1.2 Orbit Errors
7.3.2 Data Processing Errors
7.4 Ionospheric Products
7.5 GNSS-RO Ionospheric Applications
7.5.1 Establishing Ionospheric Models
7.5.2 Ionospheric Tomography
7.5.3 Monitoring Ionospheric Anomalies
7.5.4 Ionospheric Scintillation
References
Part III: GNSS Reflectometry and Remote Sensing
Chapter 8: Theory of GNSS Reflectometry
8.1 Introduction
8.2 Multi-static System: Geometry and Coverage
8.3 Specular and Diffuse Scattering
8.4 Delay and Doppler
8.5 Reflectivity Levels and Polarization Issues
8.6 Scattering Theories
8.6.1 Kirchhoff or Tangent Plane Approximation (KA)
8.6.1.1 KA in Stationary-Phase Approximation (Kirchhoff Geometrical Optics, KGO)
8.6.1.2 KA in Physical Optics Approximation (KPO)
8.6.1.3 Alternative Formulations of KA
8.6.1.4 Validity Limits of Kirchhoff Approximations
8.6.2 Summary of Other Methods
8.6.3 Received GNSS Scattered Fields
8.6.4 The Bi-static Radar Equation for GNSS Modulated Signals
8.7 Noise and Coherence Issues
8.8 Systematic Errors
8.9 PARIS Interferometric Technique (PIT)
8.10 Observables
References
Chapter 9: Ocean Remote Sensing Using GNSS-R
9.1 Altimetry
9.1.1 Group Delay Altimetry
9.1.2 Atmospheric Corrections
9.1.3 GNSS-R Ocean Altimetric Performance
9.2 Ocean Surface Roughness
9.2.1 Surface Modelling
9.2.1.1 Ocean Wave Spectra
9.2.1.2 Surface Slopes Probability
9.2.1.3 Surface Generation
9.2.2 Retrieval Approaches
References
Chapter 10: Hydrology and Vegetation Remote Sensing
10.1 Introduction
10.2 Hydrology GNSS-Reflectometry
10.3 Hydrology Sensing from GNSS-R
10.3.1 Waveform Correlation
10.3.2 Interference Pattern Technique (IPT)
10.3.3 Hydrology Sensing from GNSS
10.3.4 GNSS-R Scattering Properties
10.3.5 GNSS-R Polarization
10.4 GNSS-R Forest Biomass Monitoring
10.5 Summary
References
Chapter 11: Cryospheric Sensing Using GNSS-R
11.1 Dry Snow Monitoring
11.1.1 Dry Snow Reflection Model: Multiple-Ray Single-Reflection
11.1.2 Dry Snow Observable: Lag-Hologram
11.2 Wet Snow Monitoring
11.2.1 Observations from Space-Borne GNSS-R
11.2.2 Observations from Ground GNSS-R
11.3 Sounding the Sea Ice Conditions
References
Chapter 12: Summary and Future Chances
12.1 Status of GNSS Remote Sensing
12.1.1 Atmospheric Sensing
12.1.2 Ocean Sensing
12.1.3 Hydrology Sensing
12.1.4 Cryosphere Mapping
12.2 Future Developments and Chances
12.2.1 More GNSS Networks and Constellations
12.2.2 Advanced GNSS Receivers
12.2.3 New Missions and Systems
12.2.4 New and Emerging Applications
12.3 Summary
References
Index