EGU2020-6808
https://doi.org/10.5194/egusphere-egu2020-6808
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Correlation based snapshot models of the archeomagnetic field

Maximilian Arthus Schanner1, Stefan Mauerberger2, Monika Korte1, and Matthias Holschneider2
Maximilian Arthus Schanner et al.
  • 1Helmholtz Centre Potsdam German Research Centre for Geoscienes GFZ, Section 2.3 Geomagnetism, Germany (arthus@gfz-potsdam.de)
  • 2University of Potsdam, Applied Mathematics, Germany

For the global time stationary geomagnetic core field, a new modeling concept for Holocene archeomagnetic data is presented. Major challenges consist of the uneven data distribution, missing vector field components and non-linear relations between observations and the geomagnetic potential. Instead of a truncated spherical harmonics approach, we propose a fully Bayesian, Gaussian process based model. Inherently, the Bayesian approach provides location dependent uncertainties.

The geomagnetic potential is assumed to be a Gaussian process whose covariance structure is given by an explicit kernel function, including several hyperparameters. For this kind of non-parametric models, the full Bayesian posterior is numerically intractable. Instead, we propose an approximate computation using a Bayesian update system. In a first step, the full vector records are used to obtain, within Laplace approximation, a rough field estimate. This estimate serves as a point of linearization for the non-linear observations. The approximate posterior is then given by a Gaussian mixture. Marginals for all relevant parameters and the field itself can be computed. We are able to quantify the impact of data coverage on uncertainty reduction.

How to cite: Schanner, M. A., Mauerberger, S., Korte, M., and Holschneider, M.: Correlation based snapshot models of the archeomagnetic field, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6808, https://doi.org/10.5194/egusphere-egu2020-6808, 2020

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