EGU21-7235, updated on 11 Apr 2024
EGU General Assembly 2021
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

A First Assessment of the interconnection between celestial pole offset and geomagnetic field variations

Sadegh Modiri1,2, Robert Heinkelmann1, Santiago Belda3,4, Mostafa Hoseini5, Monika Korte1, Zinovy Malkin6,7, José M. Ferrándiz3, and Harald Schuh1,2
Sadegh Modiri et al.
  • 1GFZ German Research Centre for Geosciences, Potsdam, Germany (
  • 2Technische Universitat Berlin, Institute for Geodesy and Geoinformation Science, Berlin, Germany
  • 3Universidad de Alicante, Space Geodesy Group, Applied Mathematics, EPS, Alicante, Spain
  • 4Image Processing Laboratory (IPL) - Laboratory of Earth Observation (LEO), University of Valencia, Valencia, Spain
  • 5Department of Civil and Environmental Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
  • 6Pulkovo Observatory- St. Petersburg, Astronomical Observatory, St. Petersburg, Russian Federation
  • 7Kazan Federal University, Kazan, Russian Federation

The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) provides the geodetic infrastructure needed to monitor the Earth system.. The understanding of forced temporal variations of celestial pole motion (CPM) could bring us significantly closer to meeting the GGOS goals (i.e. 1 mm accuracy and 0.1 mm/year stability on global scales in terms of the ITRF defining parameters). Besides astronomical forcing, CPM excitation depends on the processes in the fluid core and the core-mantle boundary. The same processes are responsible for the variations of the geomagnetic field (GMF). This study investigates the interconnection between the celestial pole offset (CPO) and effective geophysical processes that contribute to the Earth's rotational variation. We use the CPO time series obtained from very long baseline interferometry (VLBI) observations together with the latest GMF data such as geomagnetic jerk and magnetic dipole moment, and a state-of-the-art geomagnetic field model to explore the correlation between CPM and GMF. 
Our results confirm the findings of previous studies, revealing that  substantial free core nutation (FCN) disturbance occurred at the epochs close to the GMJ events. The results also reveal some common features in the FCN and GMF variation, which show the potential to improve knowledge regarding the GMF's contribution to the Earth's rotation.

How to cite: Modiri, S., Heinkelmann, R., Belda, S., Hoseini, M., Korte, M., Malkin, Z., Ferrándiz, J. M., and Schuh, H.: A First Assessment of the interconnection between celestial pole offset and geomagnetic field variations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7235,, 2021.


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