Global Geodetic Observing System

Global Geodetic Observing System
Name	Global Geodetic Observing System
Abbreviation	GGOS
Formation	2003
Purpose	"Integrate geodetic observations to monitor Earth's shape, rotation, gravity field, and associated changes"
Parent organization	International Association of Geodesy
Headquarters	International Astronomical Union

Contents

Global Geodetic Observing System is an integrated observing system that coordinates global International Association of Geodesy activities to provide the geodetic reference frames and time-variable information required by United Nations conventions, World Meteorological Organization applications, and Earth system science. It delivers precise products used by European Space Agency, National Aeronautics and Space Administration, Japan Aerospace Exploration Agency, National Oceanic and Atmospheric Administration, and national mapping agencies for positioning, navigation, and monitoring of geodynamic processes. GGOS underpins international initiatives such as the Global Climate Observing System, Group on Earth Observations, and contributes to studies relevant to Intergovernmental Panel on Climate Change assessments.

Overview

GGOS combines observations from space geodetic techniques and terrestrial networks to realize the terrestrial reference frame and time-variable Earth system parameters required by International Terrestrial Reference Frame, International Celestial Reference Frame, and global timekeeping standards like Coordinated Universal Time. It synthesizes contributions from programs such as the International GNSS Service, International VLBI Service for Geodesy and Astrometry, International Laser Ranging Service, and International DORIS Service. GGOS products support operations by agencies including the European Commission, Federal Aviation Administration, European Space Operations Centre, and scientific projects like GRACE and GOCE mission analyses.

GGOS was established under the auspices of the International Association of Geodesy in response to recommendations from panels involving experts associated with Committee on Space Research, International Astronomical Union, and the World Geodetic System. Its early development paralleled milestones set by the release of WGS84 updates, the realization of successive International Terrestrial Reference Frame versions, and the deployment of satellite missions such as TOPEX/Poseidon and Jason-1. Institutional coordination drew on heritage from the International GPS Service and cooperative frameworks used by the Intergovernmental Oceanographic Commission and United Nations Educational, Scientific and Cultural Organization.

GGOS has principal objectives aligned with sustaining the global International Terrestrial Reference System, monitoring mass redistribution related to Greenland ice sheet and Antarctic ice sheet changes, and providing geodetic inputs for sea level rise and crustal deformation studies relevant to United Nations Framework Convention on Climate Change reporting. Core components include networks and services: International GNSS Service, International VLBI Service for Geodesy and Astrometry, International Laser Ranging Service, International DORIS Service and related collocated sites tied to space missions such as Sentinel-3, ICESat-2, and Landsat for synergy.

GGOS integrates space-based techniques: Global Positioning System, Very Long Baseline Interferometry, Satellite Laser Ranging, and DORIS tracking, together with airborne and terrestrial sensors deployed by institutions like National Geospatial-Intelligence Agency, Bundesamt für Kartographie und Geodäsie, and national cadastral agencies. Collocation of instruments at fundamental geodetic sites enables tie measurements among systems used by missions such as GRACE Follow-On and the Jason series. Ground infrastructure includes fiducial markers maintained in networks associated with European Reference Frame, North American Datum, and regional reference frames employed by Ordnance Survey and Geoscience Australia.

GGOS aggregates heterogeneous data streams into standardized products: realizations of the International Terrestrial Reference Frame, Earth orientation parameters used by International Earth Rotation and Reference Systems Service, gravity field models employed in analyses by Ducks Unlimited and hydrology groups, and time series for crustal motion used in hazard assessments by agencies such as United States Geological Survey and British Geological Survey. Data stewardship follows interoperability principles promoted by Group on Earth Observations and infrastructure guidelines from Committee on Earth Observation Satellites. Product distribution interfaces support operational consumers like European Centre for Medium-Range Weather Forecasts and scientific users publishing in outlets including Nature and Journal of Geophysical Research.

GGOS outputs enable precise positioning for International Space Station operations, geohazard monitoring important to United Nations Office for Disaster Risk Reduction, and climate research informing Intergovernmental Panel on Climate Change assessments. Applications include monitoring of sea level rise for coastal management by agencies such as UNESCO and National Oceanic and Atmospheric Administration, glacial mass balance studies impacting World Bank resilience planning, and support for navigation systems used by International Maritime Organization and aviation regulators like International Civil Aviation Organization.

GGOS is coordinated through the International Association of Geodesy governance structure with advisory input from bodies including the International Astronomical Union, Committee on Space Research, and the World Meteorological Organization. Collaboration spans national mapping agencies, space agencies such as NASA, ESA, JAXA, and research institutions including Scripps Institution of Oceanography and GFZ German Research Centre for Geosciences. Funding and programmatic decisions often involve multinational consortia, intergovernmental agreements and partnerships with organizations like the Group on Earth Observations and United Nations entities.