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.
We aim to keep the glossary as comprehensive and accurate as possible. If you identify missing terms or would like to suggest updates or corrections, please feel free to contact us (website admin).
A
- Absolute Gravimetry
- AC - Analysis Center
- ACC - Analysis Center Coordination / Coordinator
- ADT - Absolut Dynamic Topography
- AFREF - African Reference Frame
- AGrav - Absolute Gravity Database
- AGU – American Geophysical Union (AGU)
- Altimetry
- APREF - Asia-Pacific Reference Frame
- ASI – Italian Space Agency
- Atmospheric Loading
- Atomic Clock
B
- Baseline
- Bathymetry
- BCRS – Barycentric Celestial Reference System
- BDS - BeiDou Navigation Satellite System
- Bernese GNSS Software
- BEV - Federal Office of Metrology and Surveying (Austria)
- BGI - International Gravimetric Bureau
- BIPM – Bureau International des Poids et Mesures
- BKG - Bundesamt für Kartographie und Geodäsie
- Bouguer Anomaly
- Bruns’ Formula
C
- Cadastre
- Carrier Phase
- Cartesian Coordinate System
- CATREF – Combination and Analysis of Terrestrial Reference Frames
- CDDIS - NASA’s Crustal Dynamics Data Information System
- Centrifugal Potential
- CEOS – Committee on Earth Observation Satellites
- CHAMP - CHAllenging Minisatellite Payload
- Chandler Wobble
- CIO - Celestial Intermediate Origin
- CIP - Celestial Intermediate Pole
- Clock Bias
- CNES – France National Centre for Space Studies
- COB - Communication and Outreach Branch
- CODATA – Committee on Data for Science and Technology
- Coordinate System
- COPDESS - Coalition on Publishing Data in the Earth, Space and Environmental Sciences
- Copernicus
- CORS - Continuously Operating Reference Stations
- COSPAR – Commission on Space Research of International Science Council (ISC)
- COST-G - International Combination Service for Time-variable Gravity Fields
- CPO - Celestial Pole Offsets
- CRF - Celestial Reference Frame
- CRS - Coordinate Reference System
- CryoSat
- Cryosphere
- CTOH - Centre de Topographie des Océans et de l'Hydrosphère
- Cycle Slip
D
- Datum Transformation
- Deflection of the Vertical
- Degree and Order
- DEM - Digital Elevation Models
- DGFI - Deutsches Geodätisches Forschungsinstitut (DGFI-TUM)
- Digital Twin Earth
- Disturbing Potential
- DLR - German Aerospace Center
- DOI - Digital Object Identifier
- DOP - Dilution of Precision
- DORIS - Doppler Orbitography and Radiopositioning Integrated by Satellite
- DOT - Dynamic Ocean Topography
- DPOD - DORIS extension to the current ITRF for Precise Orbit Determination
- DSM - Digital Surface Models
- DTM - Digital Terrain Models
- DTRF/DTRF2020
- dUT1
- Dynamic Height
E
- Earth flattening
- Earth Observation
- Earth Rotation
- Earth System
- Earth system components
- ECEF - Earth-Centered, Earth-Fixed Coordinates
- Ecliptic
- ECMWF – European Centre for Medium-Range Weather Forecasts
- EGU – European Geoscience Union (EGU)
- EGVs – Essential Geodetic Variables
- Electron Density
- Ellipsoid (Reference Ellipsoid)
- Ellipsoidal Height
- EOP - Earth Orientation Parameter
- EPN - European Permanent Network of EUREF
- EPOS – European Plate Observing System
- Equipotential Surface
- ERA - Earth Rotation Angle
- ESA - European Space Agency
- Etalon – Satellite Mission
- ETRS89 - European Terrestrial Reference System 1989
- EUREF - Reference Frame Sub Commission for Europe
F
- FAGS - Federation of Astronomical and Geophysical Data Analysis Services
- FES2014b - Finite Element Solution 2014b
- FIG – International Federation of Surveyors
- Free-Air Gravity Anomaly
- Fundamental Station
G
- GALILEO
- GAMIT – GNSS Analysis MIT
- GAR19 - Global Assessment Report for 2019
- GATEW - GNSS Augmentation of Tsunami Early Warning
- GCOS – Global Climate Observing System
- GCRS – Geocentric Celestial Reference System
- GENESIS - ESA Satellite Mission
- GEO – Group on Earth Observations
- Geocenter
- Geocenter Motion
- Geodesy
- GeodesyML
- Geodetic CRS
- Geodetic Datum
- Geodetic Network
- Geodetic Observatory
- Geographic Coordinates
- Geoid
- Geoid Undulations
- Geometric Geodesy
- Geometric Height
- Geopotential
- Geopotential Coefficients
- Geopotential Number
- 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 – Geodetic Integrated Navigation Analysis 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
- GMT - Generic Mapping Tool
- GNSS - Global Navigation Satellite Systems
- GNSS-A
- GNSS-R - Reflectometry
- GNSS-RO - GNSS Radio Occultation
- GOCE
- GOOS – Global Ocean Observing System
- GPS - Global Positioning System
- 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
- Gravity
- Gravity Anomaly
- Gravity Disturbance
- Gravity Field
- Gravity Measurement
- Gravity Potential
- Gravity Vector
- GRC - Geophysical Risk and Sustainability
- Groundwater
- GRS - Geodetic Reference System
- GSI – Geospatial Information Authority of Japan
- GTEWS - GNSS enhancement for Tsunami Early Warning Systems
H
- Height Anomaly
- Height Definition
- 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
- 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
- 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
- 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
- InSAR - Interferometric Synthetic Aperture Radar
- Instrumental Drift
- Integer Ambiguity
- IOC - Intergovernmental Oceanographic Commission
- Ionosphere
- IPCC – Intergovernmental Panel on Climate Change
- IPP - Ionospheric Pierce Point
- IRNSS NavIC - Indian Regional Navigation Satellite System
- ISC - International Science Council
- ISG - International Service for the Geoid
- 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
- 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
M
- Mapping
- MDT - Mean Dynamic Topography
- Mean-Tide System
- MEO - Medium Earth Orbit
- Molodensky Theory
- MSL - Mean Sea Level
- MSS - Mean Sea Surface
- Multipath
N
- NAREF - North American Reference Frame
- NASA - National Aeronautics and Space Administration
- Navigation
- Network Adjustment
- Neutral Atmosphere
- NGS - National Geodetic Survey
- NIST – National Institute of Standards and Technology
- NNR - No-Net-Rotation
- NOAA - National Oceanic and Atmospheric Administration
- NOC - National Oceanography Centre
- Non-Tidal Gravity Variation
- Normal Gravity
- Normal Gravity Field
- Normal Height
- NRCan – Natural Resources Canada
- NRT - Near Real Time
- Nutation
O
- Observation Equation
- Ocean Tides
- Oceanic Loading
- OGC – Open Geospatial Consortium
- OMCT – Ocean Model for Circulation and Tides
- Orthometric Height
- OSGEO – Open Source Geospatial Foundation
- OST - Ocean Surface Topography
P
- PCO/PCV – Phase Center Offset / Phase Center Variation
- 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
- PPP - Precise Point Positioning
- Precession
- Pseudorange
- PSMSL - Permanent Service for Mean Sea Level
Q
R
- Radio Source
- Reference Ellipsoid
- Reference Frame
- Reference Potential (W₀)
- Reference System
- RLG - Ring Laser Gyroscope
- ROB - Royal Observatory of Belgium
- RT - Real Time
S
- S/X
- SARAO - South African Radio Astronomy Observatory
- Satellite Ephemeris
- Satellite Gravimetry
- Scale of the Reference Frame
- SCAR - Scientific Committee on Antarctic Research
- SCoG – Subcommittee on Geodesy (UN-GGIM)
- Sentinel
- SG - Superconducting Gravimeters
- 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
- Space Weather
- Spherical Harmonics
- SSH - Sea Surface Height
- SSTop - Sea Surface Topography
- Statens Kartverk – Norwegian Mapping Authority
- STEC - Slant Total Electron Content
- Stochastic Model
- Stokes’ Formula
- 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
- Thermosphere
- Tidal Gravity Variation
- Tidal Loading
- Tide Gauge
- Tide-Free System
- Tides
- TIGA - Tide Gauge Benchmark Monitoring
- Tiltmeters
- TIO - Terrestrial Intermediate Origin
- TRF - Terrestrial Reference Frame
- Triangulation
- Trilateration
- Troposphere
- TRS - Terrestrial Reference System
- TT – Terrestrial Time
U
- 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
- 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
- VLBI - Very Long Baseline Interferometry
- VTEC - Vertical Total Electron Content
W
Z
IAG as part of the IUGG
IAG Related Organisations
IAG collaborates closely with numerous organizations within geodesy and beyond. See the list for details.
This website is provided by the IAG Secretariat and the GGOS Coordinating Office, which are hosted by the BEV – Federal Office of Metrology and Surveying (Bundesamt für Eich- und Vermessungswesen) in Vienna, Austria.