The overall goal of IGFS is to coordinate the servicing of the geodetic and geophysical community with gravity field-related data, software and information. The combined data of the IGFS entities data will include both satellite-derived global models, terrestrial, airborne, satellite and marine gravity observations, earth tide data, GPS leveling data, digital models of terrain and bathymetry, as well as ocean gravity field and geoid from satellite altimetry. Both the static and the temporal variations of the gravity field will be covered by the IGFS. IGFS will – in cooperation with the services – make a special effort in trying to secure release of data from national and international institutions holding data on the spatial and temporal gravity variations, geoid and the surface heights of the Earth, to make them widely available to the scientific community. IGFS will coordinate regional conferences, tutorials and schools to train young scientists and members of national institutions in the various aspects of the gravity field science, computations, and data collection. IGFS will maintain a publication activity related to the gravity field, especially through “Newtons Bulletin”. see also: http://igfs.topo.auth.gr/

Structure

The Service is organized by means of the following structure:

• Advisory Board
• Central Bureau
• Services and Centres

The Advisory Board is composed of:

• Directors (or their delegates) of each of the Centres of IGFS
• Chairmen of the IGFS working groups
• Presidents (or their delegates) of the IAG Commissions related to the Service work
• A representative of the IAG Executive Committee (IAG-EC)
• Two members appointed among the affiliates.

The Advisory Board

• Coordinate the scientific strategy
• Coordinates the joint activity of the Centres
• Oversees the participation of the Service in international projects
• Presents to the IAG-EC proposals for associating new centres to the Service
• Elects the IGFS affiliates upon nomination by the Centres or affiliates.

The Advisory Board is appointed for four years between IUGG General Assemblies. The existing Advisory Board selects new members as required, and nominates a president for the IGFS. The election is to be confirmed by the IAG Executive Committee. The Advisory Board makes decisions by majority vote; it can also vote by email. The Advisory Board decides the Terms of Reference for IGFS.

IGFS Services and Centres

The IGFS Services and Centres are the “operating arms” of IGFS. The Centres are committed to produce services and products related to the gravity field of the Earth and/or the planets. The Centres within IGFS are approved by the IAG EC. Centres can include bodies of structures external to the IAG (e.g., the BGI which is reporting to FAGS). The Centres will have their own governing bodies, nominated according to internal rules, also taking into account the interests of the supporting entities. In particular, each governing body will have a Director, elected according to internal rules. Centres will maintain a list of data and products, providing them to the general public according to their policy of dissemination; they will deliver services in the form of data archiving, data analysis, dissemation, software, training, initiation of measurement and data compilation campaigns etc. The activities of each Centre will be reviewed annually by the IAG-EC.

COST-G: The International Combination Service for Time-variable Gravity Fields is the Product Center of the International Gravity Field Service (IGFS) for time-variable gravity fields. COST-G provides consolidated monthly global gravity models in terms of spherical harmonic (SH) coefficients and thereof derived grids by combining solutions from individual analysis centers (ACs).

IHRF CC: The International Height Reference Frame Coordination Center is a central coordinating body responsible for managing and maintaining the International Height Reference System (IHRS) & the International Height Reference Frame (IHRF). It operates under the International Gravity Field Service (IGFS) and oversees, through its permanent components (Coordination Center, Conventions’ Coordination, Reference Network Coordination, Associate Analysis Centres, and Combination Coordination), various components involved in realizing and sustaining the IHRS/IHRF.

IGFS Central Bureau

The IGFS Central Bureau will act as the IGFS Technical Centre, and handle the daily communications of the IGFS. The Central Bureau will handle the practical collection and homogenization of gravity field data, including the construction of unified gravity field models, e.g. high-resolution spherical harmonic models, and the practical advice and implementation on definitions on gravity field standards such as tidal correction principles, vertical datums, etc. The Central Bureau will also be responsible for the IGFS web site (to be implemented). The IGFS Central Bureau is presently hosted by the Department of Geodesy and Surveying, Aristotle University of Thessaloniki, Greece. (last update 10.2020)