List of Acronyms
| 1D | One-Dimensional |
| 2D | Two-Dimensional |
| ALD | Azimuth Look Direction |
| ALOS | Advanced Land Observing Satellite |
| AMI | Active Microwave Instrument |
| ASI | Agenzia Spaziale Italiana (Italian Space Agency) |
| AVHRR | Advanced Very High Resolution Radiometer |
| BTTB | Block-Toeplitz Toeplitz-Block |
| CFE | Comisión Federal de Electricidad, Mexico |
| CLARA’96 | Clouds and Radiation experiment 1996 |
| CMOD4 | C-band Model 4 (empirically derived model function to relate normalized radar cross-section with wind speed and direction) |
| CNES | Centre National D’Etudes Spatiales |
| CPGF | Cerro Prieto Geothermal Field |
| CSA | Canadian Space Agency |
| CTRS | Conventional Terrestrial Reference System |
| DEM | Digital Elevation Model |
| DEOS | Delft Institute for Earth-Oriented Space Research |
| DFD | Deutsches Fernerkundungsdatenzentrum (German Remote Sensing Data Center) |
| DIAL | Differential Absorption Lidar |
| DLR | Deutsches Zentrum für Luft- und Raumfahrt e.V. (German Aerospace Center) |
| DPWV | Differential Precipitable Water Vapor |
| DUT | Delft University of Technology |
| ERS | European Remote Sensing Satellite |
| ESA | European Space Agency |
| fBm | Fractional Brownian Motion |
| FFA | Far Field Approximation |
| FFT | Fast Fourier Transform |
| FM | Frequency Modulated |
| GISARE | Groningen Interferometric SAR Experiment |
| GNSS | Global Navigation Satellite Systems |
| GPS | Global Positioning System |
| IEEE | Institute of Electrical and Electronics Engineers |
| IERS | International Earth Rotation Service |
| IGS | International GPS Service for Geodynamics |
| InSAR | Interferometric SAR / SAR interferometry |
| IPW | Integrated Precipitable Water |
| I/Q | In-Phase (real), Quadrature (imaginary) |
| IRM | Interferometric Radar Meteorology |
| ITRF | IERS Terrestrial Reference Frame |
| JERS | Japanese Earth-Resources Satellite |
| JPL | Jet Propulsion Laboratory |
| LOS | Line of Sight |
| LT | Local Time |
| MCF | Minimal Cost Flow |
| MIT | Massachusetts Institute of Technology |
| MSC | Mesoscale Shallow Convection |
| NAM | Nederlandse Aardolie Maatschappij B.V. |
| NAP | Normaal Amsterdams Peil (Dutch vertical reference datum) |
| NASA | National Aeronautics and Space Administration |
| NASDA | National Aeronautics and Space Development Agency (Japan) |
| NDVI | Normalized Differential Vegetation Index |
| NOAA | National Oceanic and Atmospheric Administration |
| PAF | Processing and Archiving Center |
| Probability Density function | |
| PLW | Precipitable Liquid Water |
| PRARE | Precise Range and Rate Equipment |
| PRF | Pulse Repetition Frequency |
| PWV | Precipitable Water Vapor |
| radar | Radio detection and ranging |
| RAR | Real Aperture Radar |
| RCS | Radar Cross Section |
| RH | Relative Humidity |
| RMS | Root Mean Square |
| RRF | Range Reference Function |
| SAR | Synthetic Aperture Radar |
| s/c | Spacecraft |
| SIR | Shuttle Imaging Radar, Spaceborne Imaging Radar |
| SLAR | Side Looking Airborne Radar |
| SLC | Single-Look Complex |
| SLR | Satellite Laser Ranging / (Side Looking Radar) |
| SNR | Signal-to-Noise Ratio |
| SPOT | System Probatoire d’Observation de la Terre |
| SRTM | Shuttle Radar Topography Mission |
| SWST | Sampling Window Start Time |
| TEC | Total Electron Content |
| TECU | Total Electron Content Unit |
| TID | Traveling Ionospheric Disturbance |
| UTC | Universal Coordinated Time |
| VLBI | Very Long Baseline Interferometry |
| VTEC | Vertical Total Electron Content |
| WGS84 | World Geodetic Survey 1984 |
| WV | Water Vapor |
| X-SAR | X-band Synthetic Aperture Radar |
List of Symbols
| ∅ | Initialization value, usually determined for reference surface |
| A | Design matrix |
| Aκ | Part of the design matrix corresponding to observation κ |
| B | Baseline |
| B∥ | Parallel baseline |
| B⊥ | Perpendicular baseline |
| B°⊥ | Perpendicular baseline for range to resolution cell on the reference surface |
| B⊥crit | Critical (perpendicular) baseline |
| Bℎ | Horizontal baseline |
| Bᵛ | Vertical baseline |
| Bᴬ | Azimuth time bandwidth |
| Bᴿ | Range bandwidth |
| Bᴰᵒᵖ | Doppler bandwidth |
| ᶜ | Speed of light = 299792458 m/s |
| C | Structure function coefficient |
| C ẋ | Variance-covariance matrix of the estimated parameters |
| Cφ | Variance-covariance matrix |
| Cs | Variance-covariance matrix of atmospheric delay |
| Dᵃ | Antenna width (m) |
| D{.} | Dispersion operator, second moment, or variance-covariance matrix |
| Dᵢ | Fractal dimension for a signal |
| Dᵏ | Slant deformation for observation ᵏ |
| Dχ | Structure function of parameter χ |
| E{.} | Expectation operator, ensemble average, first moment, or mean |
| ℯ | Partial pressure of water vapor (hPa) |
| f | Frequency |
| f o | Carrier (center) frequency |
| fᴰ | Doppler frequency |
| fᴰ c | Doppler centroid frequency |
| fᵖ | Pulse repetition frequency (PRF) (cycles/m) |
| f∮ | Fringe frequency |
| ℎᵖ | Altitude of point ᵖ |
| ℎꜱᵖ | Height of the sub-ionospheric point (m) |
| ℎ ²π | Height ambiguity (m) |
| H | Altitude; Haussdorff measure |
| H κ | Topographic height for observation κ |
| I | Integrated Precipitable Water |
| κ | Wavenumber |
| L | Effective number of looks |
| Lα | Antenna length (m) |
| L1,L2 | GPS carrier phase frequencies (Ll=l.57542 GHz, L2=l.22760 GHz) |
| L3 | GPS ionospheric-free linear combination |
| m | Number of observations |
| n | Number of parameters (unknowns) |
| nᵉ | Electron content (m-3) |
| n∥ | Parallel error baseline |
| n⊥ | Perpendicular error baseline |
| N | Refractivity, Geoid height |
| Probability density function | |
| P | Total atmospheric pressure (hPa) |
| P ᵡ | Power spectrum of parameter ᵡ |
| Qφ | Real positive-semidefinite cofactor matrix |
| R | (Slant) range (m) |
| R1 | Slant range between reference (master) satellite and resolution cell (m) |
| R2 | Slant range between secundary (slave) satellite and resolution cell (m) |
| Sc | Chirp rate or Frequency slope ( S-2) |
| STiK | Slant atmospheric delay for pixel at (m) |
| t | Time (s) |
| T | Temperature (K) |
| υ | Velocity (m/s) |
| υ | Hermitian product γ1γ2* |
| υ s/c | Velocity of spacecraft (m/s) |
| ᵚᵏ | Integer ambiguity number |
| w | Liquid water content (g m-3) |
| w{.} | Wrapping operator |
| wᵃ | Radar footprint width in azimuth (3dB) |
| x | Vector of parameters |
| ẋ | Best linear unbiased estimator of the unknown parameters x |
| Ẋs/c | State vector of spacecraft |
| ỿᵢ | Complex observation (phasor) ᵢ |
| Z(υ,v) | Amplitude spectrum of interferogram υ and v are wavenumbers) |
| Z(υ,v) | Amplitude spectrum of filtered interferogram |
| α | Baseline orientation angle; Spectral exponent |
| β | Error baseline orientation angle; Spectral index |
| βᵣ | Angular beamwidth in range direction (rad) |
| βα | Angular beamwidth in azimuth direction (rad) |
| γ | Coherence (complex) |
| γgeom | Coherence reduction due to geometric (baseline) decorrelation |
| γdc | Coherence reduction due to Doppler centroid decorrelation |
| γtemporal | Coherence reduction due to temporal decorrelation |
| γvol | Coherence reduction due to volume decorrelation |
| γprocessing | Coherence reduction due to processing induced decorrelation |
| γthermal | Coherence reduction due to thermal noise |
| ℾᵪ | Semi-variogram of parameter ᵪ |
| ∂∅ | Change in look angle |
| Δα | Focused azimuth resolution |
| Δᵣ | Slant range resolution |
| ΔR | Slant range difference |
| ΔRdefo,p | Slant range difference due to deformation |
| ℰ | Vector of observation errors |
| ζ | Local terrain slope w.r.t. reference surface (positive towards the radar) ζ =∅inc-∅loc |
| ∅ | Look angle |
| ∅inc | Incidence angle, defined with respect to the global vertical at the scene |
| ∅loc | Local incidence angle, defined with respect to the local vertical at the ∅inc=∅loc-ζ |
| ⱴ | Reference phase (rad) |
| kN | 4π/⋋ |
| ⋋ | Radar wavelength |
| Ʌ | Geographic longitude in WGS84 |
| μ | Mean |
| p | Local earth radius (m); Horizontal distance between two resolution cells. |
| pχ | Autocorrelation function of parameter χ |
| σ2 | a priori variance factor |
| σ0 | “Sigma nought” or Radar Cross Section (RCS). Average power reflectivity or scattering coefficient per unit surface area |
| τ | Pulse length |
| τc | Effective pulse length |
| ∅ | Absolute interferometric phase, including reference phase |
| ∅w | Wrapped interferometric phase, including reference phase |
| ∅ | Geographic latitude in WGS84 |
| ∅r | Off-center beam angle in range direction (rad) |
| ∅a | Off-center beam angle in azimuth direction (rad) |
| ∅s | Squint angle (rad) |
| ∅N | Phase noise (rad) |
| φ | Absolute interferometric phase, reference phase subtracted |
| φw | Wrapped interferometric phase, reference phase subtracted |
| φk | Stochastic phase observation |
| φ | Real stochastic vector of observations |
| ψ | Phase (rad) |
| ψscat | Scattering contribution to the phase value (rad) |
| Ωk | Ratio between of B⊥ deformation pair and of B⊥ topographic pair |
| ℕ | Set of natural numbers |
| ℝ | Set of real numbers |
| ℤ | Set of integer numbers |
| ℂ | Set of complex numbers |
| ℱ | Fourier transform |