Working Group: Geomagnetic field modeling

List of the modeling group members:

•  Dr. Seiki Asari
•  Mr. Alban Gebler
•  Mrs. Anne Geese
•  Prof. Mohamed Hamoudi
•  Dr. Monika Korte
•  Mr. Praveen Kunagu
•  Dr. Vincent Lesur (leader)
•  Dr. Martin Rother
•  Dr. Ingo Wardinski

Research

See also Model page.

The section 2.3 magnetic field modeling group aims, through a careful data analysis and robust mathematical approaches, at:

•  modeling and understanding the Earth's core field,
•  mapping the Earth lithospheric field.

The modeling of the core field is done a three different time scales. On time scales of thousand years, the CALSK series of models is produced based on paleo- and archeo-magnetic data. Such models are often used in the geomagnetic community for paleomagnetic study and otherwise in studies of the long-term trends in the Earth's evolution and its magnetic field. Models based on observatory and repeat station data, with time scales of the order of 50 years, are also derived. Such models are essentially used for understanding the magnetic field dynamo. Finally short time scale models -- typically ten years -- are derived form observatory and satellite data. These models, as the GFZ Reference Internal Magnetic Model (GRIMM), have revealed the rapid evolution of the core field on annual time scales. Studies on the implication of these observations on the Earth core dynamics are ongoing. GRIMM model has also been used as parent model to derived the GFZ candidate to the International Geomagnetic Reference Field (IGRF).

The core magnetic field variations, as observed at the Earth's surface, result mainly from an advection of the field lines by the liquid movements at the top of the outer core. A significant part of our research consists in describing and understanding this flow at the core-mantle boundary. In particular we are co-estimating field and flow models in view of approaching the field modeling by assimilation methods.

In mapping of the Earth's lithospheric field two approaches are run in parallel. The first aspect consists in extracting the long wavelength crustal field from CHAMP data with limited data pre-processing in order to avoid as much as possible the introduction of spurious signal in the models. Second, in the framework of the World Digital Anomaly map (WDMAM), we are developing interpolation and correction techniques in order to build a worldwide compilation of aeromagnetic and marine data.

Finally, the group is involved in the project GEOHALO.