A Living Reference for Geodesy Terms
This glossary serves as a reference for understanding the many abbreviations and terms used in geodesy. It is directly linked to related content across the website, ensuring an up-to-date and interconnected resource. Each glossary term automatically appears as a link wherever it is used on the site.
A
- A-GPS / A-GNSS - Assisted GPS/GNSS
- AAM - Atmospheric Angular Momentum
- Absolute Gravimetry
- Absolute positioning
- AC - Analysis Center
- ACC - Analysis Center Coordination / Coordinator
- Accuracy
- ADT - Absolute Dynamic Topography
- AFREF - African Reference Frame
- AGGO - Argentine-German Geodetic Observatory
- AGrav - Absolute Gravity Database
- AGU – American Geophysical Union (AGU)
- AIUB - Astronomical Institute, University of Bern, Switzerland
- Almanac
- Altimetry
- Ambiguity resolution
- AOC - Advanced Operational Capability
- APREF - Asia-Pacific Reference Frame
- AROF - Ambiguity Resolution On the Fly
- ARP - Antenna Reference Point
- AS - Anti-spoofing
- ASI – Italian Space Agency
- Atmospheric Delay
- Atmospheric Loading
- Atomic Clock
B
- B1 / B2 / B3 - BeiDou frequencies
- Baseline
- Bathymetry
- BCRS – Barycentric Celestial Reference System
- BDS - BeiDou Navigation Satellite System
- BeiDou
- Bernese GNSS Software
- BEV - Federal Office of Metrology and Surveying (Austria)
- BGI - International Gravimetric Bureau
- Bias (code/phase bias)
- BIPM – Bureau International des Poids et Mesures
- BKG - Bundesamt für Kartographie und Geodäsie
- BOC - Binary Offset Carrier
- Bouguer Anomaly
- BPSK - Binary Phase Shift Keying
- BRD - Broadcast Ephemeris
- Broadcast Ionospheric Model
- Bruns’ Formula
C
- Cadastre
- Carrier Phase
- Cartesian Coordinate System
- Cartographic projections
- CAS - Commercial Authentication Service
- Caster
- CATREF – Combination and Analysis of Terrestrial Reference Frames
- CDDIS - NASA’s Crustal Dynamics Data Information System
- CDMA - Code Division Multiple Access
- CDP - NASA Crustal Dynamics Project
- CEGRN - Central European GPS Geodynamic Reference Network
- Centrifugal Potential
- Centrifugal Potential (Φ)
- CEO - Celestial Ephemeris Origin
- CEOS – Committee on Earth Observation Satellites
- CEP - Celestial Ephemeris Pole
- CGCN - China Geodetic Coordinate Network
- CHAMP - CHAllenging Minisatellite Payload
- Chandler Wobble
- CHIP (GNSS)
- Chronometric levelling
- CIO - Celestial Intermediate Origin
- CIP - Celestial Intermediate Pole
- CIRS - Celestial Intermediate Reference System
- Clock Bias
- CNES – France National Centre for Space Studies
- COB - Communication and Outreach Branch
- CODATA – Committee on Data for Science and Technology
- CODE - Center for Orbit Determination in Europe
- Code C/A
- Code M
- Code P
- Code Y
- Coding (GNSS)
- COMPASS
- Constellation BeiDou
- Constellation GLONASS
- Constellation GNSS
- Constellation GPS
- Control Center (GNSS)
- Convergence time
- Coordinate conversion
- Coordinate System
- COPDESS - Coalition on Publishing Data in the Earth, Space and Environmental Sciences
- Copernicus
- CORS - Continuously Operating Reference Stations
- CORS (GNSS)
- Coseismic deformation
- COSPAR – Commission on Space Research of International Science Council (ISC)
- COST-G - International Combination Service for Time-variable Gravity Fields
- Covariance Function
- Coverage factor
- CPO - Celestial Pole Offsets
- CRF - Celestial Reference Frame
- CRS - Coordinate Reference System
- Crustal loading
- CryoSat
- Cryosphere
- CS - Commercial Service (– Galileo)
- CTOH - Centre de Topographie des Océans et de l'Hydrosphère
- Cut-off Angle
- Cycle Slip
D
- Datum
- Datum Transformation
- DCB - Differential Code Bias
- Decimation (GNSS)
- Deflection of the Vertical
- Degradation (GPS)
- Degree and Order
- DEM - Digital Elevation Models
- DGFI - Deutsches Geodätisches Forschungsinstitut (DGFI-TUM)
- DGNSS - Differential GNSS
- DGPS - Differential GPS
- Differential navigation
- Digital Twin Earth
- Disturbing Potential
- DLR - German Aerospace Center
- DOI - Digital Object Identifier
- DOMES - Directory of Observing Stations (DOMES Number)
- DOP - Dilution of Precision
- Doppler Effect
- DORIS - Doppler Orbitography and Radiopositioning Integrated by Satellite
- DOT - Dynamic Ocean Topography
- Double Difference
- DPOD - DORIS extension to the current ITRF for Precise Orbit Determination
- DSM - Digital Surface Models
- DTM - Digital Terrain Models
- DTRF/DTRF2020
- Dual-frequency
- dUT1
- DVLBI - Differential VLBI
- Dynamic Height
- Dynamic positioning
E
- E1 / E5 / E6 (Galileo Frequencies)
- Earth flattening
- Earth Observation
- Earth Rotation
- Earth System
- Earth system components
- Easting (E)
- ECEF - Earth-Centered Earth-Fixed coordinate system
- ECEF - Earth-Centered, Earth-Fixed Coordinates
- Ecliptic
- ECMWF – European Centre for Medium-Range Weather Forecasts
- EGNOS - European Geostationary Navigation Overlay Service
- EGU – European Geoscience Union (EGU)
- EGVs – Essential Geodetic Variables
- Electron Density
- Ellipsoid (Reference Ellipsoid)
- Ellipsoidal Height
- EOAM - Effective Oceanic Angular Momentum
- EOP - Earth Orientation Parameter
- EPN - European Permanent Network of EUREF
- Epoch (GNSS)
- EPOS – European Plate Observing System
- Equipotential Surface
- ERA - Earth Rotation Angle
- ESA - European Space Agency
- ESTB - EGNOS System Test Bed
- Etalon – Satellite Mission
- ETRS89 - European Terrestrial Reference System 1989
- EUREF - Reference Frame Sub Commission for Europe
- EVGA - European VLBI Group for Geodesy and Astrometry
- EVRF - European Vertical Reference Frame
- EVRS - European Vertical Reference System
- EWS - Emergency Warning Service (Galileo)
F
- FAGS - Federation of Astronomical and Geophysical Data Analysis Services
- FCN - Free Core Nutation
- FDMA - Frequency Division Multiple Access
- FES2014b - Finite Element Solution 2014b
- FICN - Free Inner Core Nutation
- FIG – International Federation of Surveyors
- FKP - Area Correction Parameters
- Flattening (f)
- FOC - Full Operational Capability (GNSS)
- Free-Air Gravity Anomaly
- Fundamental Station
G
- GA – Geoscience Australia
- GAGAN - GPS Aided GEO Augmented Navigation System, India
- GALILEO
- GAMIT - GNSS At MIT
- GAMIT – GNSS Analysis MIT
- GAR19 - Global Assessment Report for 2019
- GAST - Greenwich Apparent Sidereal Time
- GATEW - GNSS Augmentation of Tsunami Early Warning
- GBAS – Ground Based Augmentation System
- GCOS – Global Climate Observing System
- GCRS – Geocentric Celestial Reference System
- GDA2020 - Geocentric Datum of Australia 2020
- GDOP - Geometric Dilution of Precision
- GEMSTONE - GEodetic Measurements by the collocation of Space Techniques ON Earth
- GENESIS - ESA Satellite Mission
- GEO – Group on Earth Observations
- Geocenter
- Geocenter Motion
- Geocentric datum
- Geodesy
- GeodesyML
- Geodetic CRS
- Geodetic Datum
- Geodetic Network
- Geodetic Observatory
- Geographic Coordinates
- Geoid
- Geoid Undulations
- Geometric Geodesy
- Geometric Height
- Geometric levelling
- Geopotential
- Geopotential Coefficients
- Geopotential Number
- Geopotential Number (C)
- GEOS - Geodetic and Earth Orbiting Satellite
- GEOSAT - GEOdesy SATellite
- Geosphere
- GEOSS – Global Earth Observation System of Systems
- GET - Géosciences Environment Toulouse
- GFZ - German Research Centre for Geosciences
- GGIM – United Nations Global Geospatial Information Management
- GGM - Global Gravity Model
- GGOS - Global Geodetic Observing System
- GGOS Core Sites
- GGOS Portal
- GGP - Global Geodynamic Project
- GGRF - Global Geodetic Reference Frame
- GGSC - Global Geodesy Supply Chain
- GIA - Glacial Isostatic Adjustment
- GIM - Global Ionosphere Maps
- Ginan - GNSS Analysis Centre Software
- GipsyX - GNSS Software
- GIS - Geographic Information Systems
- Global Water Cycle
- GLONASS - Global'naya Navigatsionnaya Sputnikovaya Sistema
- GLOSS - Global Sea Level Observing System
- GMSL - Global Mean Sea Level
- GMST - Greenwich Mean Sidereal Time
- GMT - Generic Mapping Tool
- GNSS - Global Navigation Satellite Systems
- GNSS Frequencies
- GNSS-A
- GNSS-R - Reflectometry
- GNSS-RO - GNSS Radio Occultation
- GNSS-Spoofing
- GNSS/Levelling
- GOCE
- GOOS – Global Ocean Observing System
- GPS - Global Positioning System
- GPT - Global Pressure and Temperature model
- GRACE - Gravity Recovery And Climate Experiment
- GRACE Follow-On
- GRACE-FO - Gravity Recovery And Climate Experiment Follow-On
- Gradiometry
- Gravimeter
- Gravimetry
- Gravitational Acceleration
- Gravitational Potential
- Gravitational Potential (V)
- Gravity
- Gravity Anomaly
- Gravity Disturbance
- Gravity Field
- Gravity Gradient
- Gravity Measurement
- Gravity Potential
- Gravity Vector
- GRC - Geophysical Risk and Sustainability
- Greenwich meridian
- Groundwater
- GRS - Geodetic Reference System
- GSC - Geological Survey of Canada
- GSI – Geospatial Information Authority of Japan
- GTEWS - GNSS enhancement for Tsunami Early Warning Systems
- GTRF - Galileo terrestrial reference frame
- GUM - Guide to the Expression of Uncertainty in Measurement
H
- HAM - Hydrological Angular Momentum
- HAS - High Accuracy Service
- HDOP - Horizontal Dilution of Precision
- Height Anomaly
- Height Definition
- Height system (physical vs geometric)
- Helmert Transformation (7-Parameter Transformation)
- Hydrological Loading
- Hydrosphere
I
- IAAC - Ionosphere Associate Analysis Centers
- IACS - International Union of Geodesy and Geophysics
- IAG - International Association of Geodesy
- IAG Commissions
- IAG Services
- IAGA - International Association of Geomagnetism and Aeronomy
- IAGBN - International Absolute Gravity Basestation Network
- IAHS - International Association of Hydrological Sciences
- IAMAS - International Association of Meteorology and Atmospheric Sciences
- IAPSO - International Association for the Physical Sciences of the Oceans
- IAU - International Astronomical Union
- IAVCEI - International Association of Volcanology and Chemistry of the Earth's Interior
- ICC - Inter Commission Committee's of IAG
- ICCC - IAG ICC on Climate Research for Geodesy
- ICCM - IAG ICC on Marine Geodesy
- ICCT - IAG ICC on Theory
- ICESat - Ice, Cloud and land Elevation Satellite
- ICET - International Center for Earth Tides
- ICET - International Center for Earth Tides, ROB, Brussels, Belgium
- ICG – International Committee on Global Navigation Satellite Systems of UNOOSA
- ICGEM - International Centre for Global Earth Models
- ICRF - International Celestial Reference Frame
- ICRF3
- ICRS - International Celestial Reference System
- IDEMS - International Digital Elevation Model Service
- IDS - International DORIS Service
- IERS - International Earth Rotation and Reference Systems Service
- IGETS - International Geodynamics and Earth Tide Service
- IGFS - International Gravity Field Service
- IGiK - Institute of Geodesy and Cartography, Poland
- IGN France - National Institute of Geographic and Forest Information
- IGN Spain - National Geographical Institute of Spain (Instituto Geográfico Nacional de Espania)
- IGRF - International Gravity Reference Frame
- IGRS - International Gravity Reference System
- IGS - International GNSS Service
- IGS-RTS
- IGSN71 - International Gravity Standardization Net 1971
- IGSO – International Geodetic Student Organisation
- IHRF - International Height Reference Frame
- IHRF CC - Coordination Centre
- IHRS - International Height Reference System
- ILRS - International Laser Ranging Service
- ILS - International Latitude Service
- Initial RTK
- InSAR - Interferometric Synthetic Aperture Radar
- Instrumental Drift
- Integer Ambiguity
- Integrity (GNSS)
- IOC - Intergovernmental Oceanographic Commission
- IONEX - IONospheric map EXchange format
- Ionosphere
- Ionosphere
- IPCC – Intergovernmental Panel on Climate Change
- IPP - Ionospheric Pierce Point
- IRI - International Reference Ionosphere
- IRM - IERS/International Reference Meridian
- IRNSS NavIC - Indian Regional Navigation Satellite System
- IRP
- IRS - Inertial Reference System
- ISC - International Science Council
- ISG - International Service for the Geoid
- ISGN - International Space Geodetic Network
- ISO – International Organization for Standardization and its Technical Committee ISO/TC 211
- Isostatic Gravity Anomaly
- ISPRS – International Society of Photogrammetry and Remote Sensing
- ITGRF - International Terrestrial Gravity Reference Frame
- ITGRS International Terrestrial Gravity Reference System
- ITRF - International Terrestrial Reference Frame
- ITRF2014
- ITRF2020 – International Terrestrial Reference Frame 2020
- ITRFxxxx Realisations
- ITRS – International Terrestrial Reference System
- ITU – International Telecommunication Union
- IUGG - International Union of Geodesy and Geophysics
- IVS - International VLBI Service for Geodesy and Astrometry
J
- JAXA - Japan Aerospace Exploration Agency
- JpGU – Japan Geoscience Union
- JPL - Jet Propulsion Laboratory
- JTRF - JPL Terrestrial Reference Frame
K
L
- L1 / L2 / L5 (GPS Frequencies)
- L2C
- LAGEOS - Laser Geodynamics Satellites
- Lantmäteriet – Swedish Mapping, Cadastral and Land Registration Authority
- LARES - Laser Relativity Satellite
- Least Squares Adjustment
- LEO - Low Earth Orbiter
- Level Surface
- Levelling
- LiDAR - Light Detection and Ranging
- LLR - Lunar Laser Ranging
- Local Tie
- LOD - Length of Day
- Love Numbers
- Lower Neutral Atmosphere
- LSC - Least Squares Collocation
M
- Mapping
- MCS - Master Control Station
- MDT - Mean Dynamic Topography
- Mean Tide (MT) system
- Mean-Tide System
- MEO - Medium Earth Orbit
- MGEX - Multi-GNSS Experiment
- Molodensky Theory
- Monofrequency
- MSAS
- MSL - Mean Sea Level
- MSS - Mean Sea Surface
- Multifrequency
- Multipath
- Multiplexing
N
- NAGU - (Notice Advisory to Galileo Users)
- NANU - Notice Advisory to Navstar Users
- NAREF - North American Reference Frame
- NASA - National Aeronautics and Space Administration
- Navigation
- Navigation
- Navigation Data
- Navigation Message
- NAVSTAR - NAVigation System by Timing And Ranging
- Network Adjustment
- Neutral Atmosphere
- NGS - National Geodetic Survey
- NIMA - National Imagery and Mapping Agency
- NIST – National Institute of Standards and Technology
- NMEA - National Marine Electronics Association
- NNR - No-Net-Rotation
- NNT - No-Net-Translation
- NOAA - National Oceanic and Atmospheric Administration
- NOC - National Oceanography Centre
- Non-Tidal Gravity Variation
- Normal Gravity
- Normal Gravity Field
- Normal Height
- NPPK - Network Post Processing Kinematic
- NRCan – Natural Resources Canada
- NRO - Non-Rotating Origin
- NRT - Near Real Time
- NRTK - Network Real Time Kinematic
- NTRIP - Networked Transport of RTCM via Internet Protocol
- Nutation
O
- Observation Equation
- Ocean Tides
- Oceanic Loading
- OGC – Open Geospatial Consortium
- OMCT – Ocean Model for Circulation and Tides
- Orbitography
- Orthometric Height
- OS - Open Service (Galileo)
- OSGEO – Open Source Geospatial Foundation
- OSNMA - Open Service Navigation Message Authentication
- OSR - Observation Space Representation
- OST - Ocean Surface Topography
- OTF - On The Fly ambiguity resolution
P
- Path Delay
- PCO/PCV – Phase Center Offset / Phase Center Variation
- PDOP - Position Dilution of Precision
- Phase Center
- Photogrammetry
- Physical Geodesy
- Physical Height
- Planetary Geodesy
- Plate Motion Model
- Plate Tectonics
- Plumb Line
- PNT - Positioning, Navigation and Timing
- POD - Precise Orbit Determination
- Polar Motion
- Positioning
- Post-glacial rebound
- PPP - Precise Point Positioning
- Precession
- Precise Ephemeris
- Prime Meridian
- Pseudo-kinematic positioning
- Pseudorange
- PSMSL - Permanent Service for Mean Sea Level
Q
R
- Radio Source
- Rapid static positioning
- Reference Ellipsoid
- Reference Frame
- Reference Potential (W₀)
- Reference System
- Relative positioning
- REM - Reference Earth Model
- RINEX - Receiver INdependent EXchange format
- RLG - Ring Laser Gyroscope
- ROB - Royal Observatory of Belgium
- RT - Real Time
- RTK - Real‑Time Kinematic
- RTPPP - Real-Time Precise Point Positioning
S
- S/X
- SARAO - South African Radio Astronomy Observatory
- Satellite Ephemeris
- Satellite geodesy
- Satellite Gravimetry
- SBAS - Satellite‑Based Augmentation System
- Scale of the Reference Frame
- SCAR - Scientific Committee on Antarctic Research
- SCoG – Subcommittee on Geodesy (UN-GGIM)
- Sentinel
- SG - Superconducting Gravimeters
- SHAO - Shanghai Astronomical Observatory, China
- SINEX - Solution INdependent EXchange format
- SIRGAS - Geocentric Reference System for the Americas
- SLA - Sea Level Anomalies
- SLR - Satellite Laser Ranging
- SMAP - Soil Moisture Active Passive (SMAP) Microwave Radiometer Mission
- SMOS - Soil Moisture and Ocean Salinity
- Solid Earth Tides
- SONEL - Système d’Observation du Niveau des Eaux Littorales
- SouthPAN - Southern Positioning Augmentation Network
- Space geodesy
- Space Weather
- Spherical Harmonics
- Splicing (GNSS)
- SSH - Sea Surface Height
- SSR - State Space Representation
- SSTop - Sea Surface Topography
- Statens Kartverk – Norwegian Mapping Authority
- Static positioning
- STEC - Slant Total Electron Content
- Stochastic Model
- Stokes’ Formula
- Stop-and-go positioning
- Strainmeters
- Stratosphere
- Subduction
- swisstopo – Federal Office of Topography (Switzerland)
T
- TAI-International Atomic Time
- TCG – Terrestrial Coordinated Time (Fr. Temps-Coordonnee Geocentrique)
- TEC - Total Electron Content
- Tectonic Plates
- Telluroid
- TGP - Tide-Generating Potential
- Thermosphere
- Tidal Gravity Variation
- Tidal Loading
- Tide Free (TF) system
- Tide Gauge
- Tide-Free System
- Tides
- TIGA - Tide Gauge Benchmark Monitoring
- Tiltmeters
- Time Scales
- TIO - Terrestrial Intermediate Origin
- TIRS - Terrestrial Intermediate Reference System
- TLRS - Transportable Laser Ranging System
- TOPEX - Ocean TOPography EXperiment
- Topographic mapping
- TRF - Terrestrial Reference Frame
- Triangulation
- Trilateration
- Troposphere
- TRS - Terrestrial Reference System
- TT – Terrestrial Time
- TUJJB - Turkish Union of Geodesy and Geophysics
- TZD - Tropospheric Zenith Delay
U
- UELN - United European Levelling Network
- UN - United Nations
- UN-GGCE – United Nations Global Geodetic Center of Excellence
- UN-GGIM – United Nations Initiative on Global Geospatial Information Management
- UN-SPIDER – Space-based Information for Disaster Management and Emergency Response of UNOOSA
- UNAVCO
- Uncertainty
- UNDRR – United Nations Office for Disaster Risk Reduction
- UNESCO - United Nations Educational, Scientific and Cultural Organization
- UNOOSA – United Nations Office for Outer Space Affairs
- USNO - United States Naval Observatory
- UT1 - Universal Time 1
- UTC - Coordinated Universal Time
V
- Variance–Covariance Matrix
- Vertical Gradient of Gravity
- VGOS - VLBI Global Observing System
- VieVS - Vienna VLBI Software, TU Wien, Austria
- VLBI - Very Long Baseline Interferometry
- VTEC - Vertical Total Electron Content
- VTRF - VLBI Terrestrial Reference Frame
W
Z
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