Data Assimilation activities at GFZ

Figure 1: Uncertainties of modelled tidal oceanic magnetic fields at SWARM satellite height (Saynisch et al., 2018).

GFZ's ongoing sensitivity studies relate to possible ESM observation operators

GFZ's ongoing sensitivity studies related to possible ESM observation operators were presented. This includes the sensitivity of oceanic magnetic fields with respect to oceanic conductance, climate phenomenon, climate change and various oceanic and electromagnetic model assumptions, including errors. As a reminder, sea water is a conducting medium that flows through Earth's core generated magnetic field. The resulting charge separation and induction generate characteristic electric and magnetic signals. Furthermore, altimetry was presented as proxy to improve the detectability of oceanic magnetic fields.

Gravimetry by SMART cable and GRACE satellites was presented as additional possible observation operator. GPS measurements were presented as possible constrains for hydrological load anomalies, ground deformations and Earth's elasticity distribution in an coupled model approach.

Initial assimilation studies using magnetic fields, altimetry and gravimetry observations were presented to quantify the usefulness of the proposed observation operators. The studies mostly use the Parallel Data Assimilation Framework (PDAF) and use artificial as in-situ observations. As a side note, neuronal networks were introduced as a flexible tool to bridge missing parts during ESM development. Possible applications range from model coupling, boundary error propagation, generation of surrogate observations and nonlinear inversion operators.


Irrgang, C., Saynisch, J., Thomas, M. (2017): Utilizing oceanic electromagnetic induction to constrain an ocean general circulation model: A data assimilation twin experiment. - Journal of Advances in Modeling Earth Systems, 9, 3, p. 1703-1720.DOI:

Saynisch, J., Irrgang, C., Thomas, M. (2018): Estimating ocean tide model uncertainties for electromagnetic inversion studies. - Annales Geophysicae, 36, p. 1009-1014. DOI:

Figure 2: RMS improvements in OMCT ocean model due to assimilation of radial magnetic fields (Irrgang et al., 2017).