Commissions shall promote the advancement of science, technology and international cooperation in their field. They establish the necessary links with sister disciplines and with the relevant Services. Commissions shall represent the Association in all scientific domains related to their field of geodesy. (IAG Bylaw 4)
Current Commissions and their areas of scientific responsibility are (IAG Bylaw 8):
Commission 1: Reference Frames
Establishment, maintenance, improvement of the geodetic reference frames; Advanced terrestrial and space observation technique development for the above purposes; International collaboration for the definition and deployment of networks of terrestrially-based space geodetic observatories; Theory and coordination of astrometric observation for reference frame purposes; Collaboration with space geodesy/reference frame related international services, agencies and organizations.
Commission 2: Gravity Field
Terrestrial, marine, and airborne gravimetry; Satellite gravity field observations; Gravity field modeling; Time-variable gravity field; Geoid determination; Satellite orbit modeling and determination.
Commission 3: Earth Rotation and Geodynamics
Earth orientation (Earth rotation, polar motion, nutation and precession); Earth tides; Tectonics and crustal deformation; Sea surface topography and sea level changes; Planetary and lunar dynamics; Effects of the Earth's fluid layers (e.g., post glacial rebound, loading).
Commission 4: Positioning and Applications
Terrestrial and satellite-based positioning systems development, including sensor and information fusion; Navigation and guidance of platforms; Interferometric laser and radar applications (e.g., Synthetic Aperture Radar); Applications of geodetic positioning using three dimensional geodetic networks (passive and active networks), including monitoring of deformations; Applications of geodesy to engineering; Atmospheric investigations using space geodetic techniques.