EGU General Assembly 2021
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Fast (non-)diffusive Quasi-Geostrophic Magneto-Coriolis Modes in the Earth's core

Felix Gerick1,2,3, Dominique Jault2, and Jerome Noir3
Felix Gerick et al.
  • 1Royal Observatory of Belgium, Brussels, Belgium
  • 2ISTerre, University of Grenoble, Grenoble, France
  • 3Institute of Geophysics, ETH Zurich, Zurich, Switzerland

 Fast changes of Earth's magnetic field could be explained by inviscid and diffusion-less quasi-geostrophic (QG) Magneto-Coriolis modes. We present a hybrid QG model with columnar flows and three-dimensional magnetic fields and find modes with periods of a few years at parameters relevant to Earth's core. These fast Magneto-Coriolis modes show strong focusing of their kinetic and magnetic energy in the equatorial region, while maintaining a relatively large spatial structure along the azimuthal direction. Their properties agree with some of the observations and inferred core flows. We find additionally, in contrast to what has been assumed previously, that these modes are not affected significantly by magnetic diffusion. The model opens a new way of inverting geomagnetic observations to the flow and magnetic field deep within the Earth's outer core.

How to cite: Gerick, F., Jault, D., and Noir, J.: Fast (non-)diffusive Quasi-Geostrophic Magneto-Coriolis Modes in the Earth's core, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2176,, 2021.

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