Commission 3: Earth Rotation and Geodynamics

President: Rebekka Steffen (Sweden)
Vice-President: José M. Ferrándiz (Spain)

Program of Activities

The Earth is a dynamic planet that can be explored through the analysis of geodetic data. Both space-based and terrestrial geodetic techniques offer invaluable observations, owing to their high accuracy, precision, and reliable georeferencing capabilities, for investigating a wide array of geophysical (geodynamic) processes. Spatial variations in the Earth's global static and temporal gravity field as well as global and local deformation (displacement) of the Earth's surface are used to learn more about the Earth's internal structure and dynamics. Phenomena associated with the Earth's rotation and orientation in space, such as polar motion, Universal Time (UT), Length of Day (LOD), precession/nutation, and (oceanic) pole tides, reveal insights into the dynamic behaviour of our planet. Precise measurements of these phenomena are pivotal for establishing the transformation between terrestrial and celestial reference frames. Commission 3 studies the entire range of physical processes associated with the movement and deformation of the Earth in response to both external and internal forces.

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, while others will have a broader commission-wide focus.


Commission 3 will:
  • Promote cooperation and collaboration on the theory, modelling and observation of Earth rotation and geodynamics;
  • support research into how geodesy contributes to studying natural hazards by maintaining interdisciplinary groups on volcanic deformations (with IAVCEI), present-day ice mass changes (with IACS), and phases of the seismic cycle (with IASPEI);
  • identify uncertainties in geodetic time series introduced by local to regional background processes (e.g., due to glacial isostatic adjustment models and hydrological models);
  • approach as close as possible the new models of Earth Orientation Parameters (EOPs) and other related parameters to the dynamically time-varying, actual Earth, to be adaptable to future updating of reference frames and standards;
  • foster the development of increasingly consistent and accurate geodetic multi-technique solutions;
  • encourage the exchange of ideas and data as well as the comparison of methods and results with the goal of improving accuracy, content, methods, theories, and understanding of Earth rotation and geodynamics;
  • serve the geophysical community by facilitating interactions with organizations that provide the data needed to study Earth rotation and geodynamics.To promote cooperation and collaboration on the theory, modelling and observation of Earth rotation and geodynamics.

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