Commission A2 WG Improving Theories and Models of the Earth’s Rotation (ITMER)


The main purpose of this joint WG (IAU-IAG, International Association of Geodesy) is to propose consistent updates of the Earth rotation theories and models, and their validation. The associated tasks will thus contribute to the implementation of the 2018 IAU Resolution B1 on Geocentric and International Terrestrial Reference Systems and Frames, and the 2019 Resolution 5 of the International Association of Geodesy on Improvement of the Earth’s Rotation Theories and Models.

The last resolution is the most specific for the WG assignment, and mandates :
- to encourage a prompt improvement of the Earth rotation theory regarding its accuracy, consistency, and ability to model and predict the essential EOP,
- that the definition of all the EOP, and related theories, equations, and ancillary models governing their time evolution, must be consistent with the reference frames and the resolutions, conventional models, products, and standards adopted by the IAG and its components,
- that the new models should be closer to the dynamically time-varying, actual Earth, and adaptable as much as possible to future updating of the reference frames and standards.

The work will be performed in close cooperation with IAG components, particularly Commission 3 and the Global Geodetic Observing System (GGOS), as well as the International Earth Rotation and Reference Systems service (IERS) and other current WGs dealing with the Earth rotation and standards from specific perspectives.


Working Group Members (27)


Commission A2 Rotation of the Earth

Jose Manuel Ferrándiz

Universidad de Alicante
Depto de Matematica Aplicada
Escuela Politécnica Superior
Campus de San Vicente. PO Box 99
03080 Alicante

Phone: +34 687562415
Organization website:

NCA adherence: Spain

Last updated:
November 20, 2023

Richard Gross

Jet Propulsion Laboratory
Geodynamics and Space Geodesy Group
Mail Stop 238-600
4800 Oak Grove Drive
Pasadena, CA 91109
California (CA)
United States

Phone: +1 818 354 4010
Organization website:

NCA adherence: United States

Last updated:
November 20, 2023

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