Commission 3: Earth Rotation and Geodynamics

President: Rebekka Steffen (Sweden)
Vice-President: TBD

The Terms of Reference and the structure was valid for the 2019-2023 term. Updated information will be published as soon as the structure of the commission is approved by the Executive Committee.

Program of Activities

The Earth must be considered as a dynamic system through the study of the global gravity field and its temporal variations, and the global and local deformation at the surface in order to define the Earth’s internal structure and dynamics. Consequently, geodynamics is the science that studies how the Earth moves and deforms in response to forces acting on the Earth, whether they derive from outside or inside of our planet. This includes the entire range of phenomena associated with Earth rotation and Earth orientation in space such as polar motion, Universal Time (UT) or Length Of Day (LOD), precession and nutation, the observation and understanding of which are critical to the transformation between terrestrial and celestial reference frames. Commission 3 fosters and encourages research in the areas of its sub-entities by facilitating the exchange of information and organizing symposia, either independently or at major conferences in geodesy or geophysics. Some events will be focused narrowly on the interests of the Sub-Commissions and other entities listed above, and others will have a broader commission-wide focus.


  • To promote cooperation and collaboration on the theory, modelling and observation of Earth rotation and geodynamics. 
  • To ensure development of research in Earth rotation and geodynamics by organizing meetings, symposia, and sessions at conferences and general assemblies, by creating working groups on specific topics, and by encouraging the exchange of ideas and data and the comparison of methods and results with the goal of improving accuracy, content, methods, theories, and understanding of Earth rotation and geodynamics. 
  • To serve the geophysical community by facilitating interactions with organizations that provide the data needed to study Earth rotation and geodynamics.

IAG Events