International Gravity Field Service

International Gravity Field Service
Name	International Gravity Field Service
Abbreviation	IGFS
Formation	1990s
Type	Scientific service
Headquarters	Toulouse
Region served	Worldwide
Leader title	Director
Parent organization	International Association of Geodesy

International Gravity Field Service

The International Gravity Field Service coordinates global geodesy efforts to measure the Earth's gravity field, supporting studies in geophysics, oceanography, solid Earth science and climate change. It aggregates gravity, geoid, and gravity anomaly datasets from agencies such as NASA, ESA, CNES, JPL, GFZ German Research Centre for Geosciences and national institutes, enabling integration with satellite missions like GRACE, GOCE, JASON-1, CHAMP and Envisat. The Service provides standards, reference models and validation tools used by institutions including IAG, IUGG, UNESCO, NOAA and USGS.

Overview

The Service functions as a focal point for distributing gravity-related reference frames, models and products employed by organizations such as European Space Agency, National Aeronautics and Space Administration, Centre National d'Études Spatiales, Deutsches GeoForschungsZentrum, Chinese Academy of Sciences and Geological Survey of Japan. Its outputs—geoid models, gravity anomaly grids, and vertical datum realizations—are used by projects like International Terrestrial Reference Frame, Global Geodetic Observing System and World Geodetic System 1984. Stakeholders include universities such as MIT, ETH Zurich, University of Cambridge, Caltech and Peking University.

History and Development

The Service emerged from initiatives in the late 20th century when collaborations among institutions such as IAG, IUGG, CNES, NASA/JPL and GFZ responded to needs created by satellite missions like CHAMP and TOPEX/Poseidon. Early contributors included research groups from Royal Observatory of Belgium, National Geospatial-Intelligence Agency and U.S. Naval Observatory. Milestones include integration of data from GRACE and GOCE, adoption of geoid models used alongside EGM96 and EGM2008, and alignment with international efforts such as Global Geodetic Observing System and the International Height Reference System.

Organizational Structure and Membership

The governance structure mirrors frameworks used by bodies like International Association of Geodesy, with scientific advisory boards drawing members from Universität Stuttgart, Ohio State University, University of Bonn, University of Texas at Austin and Tokyo University. Membership spans national mapping agencies such as Ordnance Survey, Institut Géographique National, Geoscience Australia and United States Geological Survey as well as research centers including Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, British Geological Survey and National Institute of Geophysics and Volcanology. Committees coordinate liaison with programs like Copernicus Programme, Committee on Earth Observation Satellites and World Climate Research Programme.

Data Products and Services

Primary products include high-resolution geoid models, gravity anomaly grids, time-variable gravity solutions, and calibration datasets compatible with satellite missions such as GRACE-FO and Sentinel-3. The Service distributes standardized datasets analogous to products from EGM2008 and provides processing tools used in conjunction with software from GIPSY-OASIS, GEOIDLab, GMT and Bernese GNSS Software. Validation exercises involve institutions such as Jet Propulsion Laboratory, European Space Operations Centre and National Center for Atmospheric Research. Data support applications in projects like Sea Level Rise assessments, Glacial Isostatic Adjustment modeling and hydrology studies managed by groups like CryoSat teams and HydroSHEDS partners.

Methods and Instrumentation

The Service integrates measurements from absolute gravimeters (manufactured by firms collaborating with FG5 networks), superconducting gravimeters operated by observatories including Wettzell Observatory and Brussels Gravimetry Observatory, airborne surveys conducted by agencies such as NOAA, and satellite gravimetry from missions like GOCE, GRACE and CHAMP. Processing employs techniques developed at GFZ, CNES, DLR and university laboratories including spectral analysis, least-squares collocation, and spherical harmonic synthesis used in models like EIGEN and ITSG-Grace2018. Calibration and intercomparison campaigns reference standards maintained by BIPM and national metrology institutes such as NIST and PTB.

Applications and Impact

Products from the Service underpin research and operational systems in areas including sea-level monitoring used by Intergovernmental Panel on Climate Change reports, groundwater depletion assessments cited by World Water Assessment Programme, tectonic studies referenced by USGS hazard assessments, and navigation systems that complement GPS and Galileo. The geoid models are crucial for national height systems implemented by mapping agencies like Ordnance Survey and Institut Géographique National and support engineering projects undertaken by firms collaborating with European Investment Bank and infrastructure bodies. Time-variable gravity informs cryosphere research by teams at University of Colorado Boulder, University of Leeds and ITC Enschede.

Collaborations and Partnerships

The Service maintains partnerships with satellite agencies including ESA, NASA, CNES, DLR, and academic consortia such as IGS, GGOS, EUREF and UN-GGIM. Collaborative projects involve international programs like GEOSS, Copernicus, CEOS and the Global Geodetic Observing System, as well as bilateral research with institutions such as ETH Zurich, National Taiwan University, Korea Astronomy and Space Science Institute and Russian Academy of Sciences. Regular workshops and symposia are held in venues like IAG General Assembly meetings, AGU conferences, EGU assemblies and topical sessions organized by COSPAR.

Category:Geodesy