GRIMM

GFZ Reference Internal Magnetic Model

The GFZ Reference Internal Magnetic Model (GRIMM) has been derived from nearly six years of CHAMP satellite data and five years of observatory hourly means. At high latitudes, full vector satellite data are used at all local times. By doing so, a separation is possible between, on one hand, the fields generated by the ionosphere and field aligned currents, and, on the other hand, the fields generated in the Earth's core and lithosphere. This selection technique leads to a data set where gaps are avoided during the polar summers allowing the modelling of the core field with an unprecedented time resolution. Order five B-splines are used to model the core field and the mapping of its acceleration is possible from 2001.5 to 2005.5 revealing a rapid and complex evolution over this time period at the Earth's surface. The energy in secular acceleration presents a smooth behaviour in time and is shown to increase continuously from 2003.5. Due to the regularisation technique introduced, the acceleration energy for spherical harmonics 6 to 11 is significantly larger than for other available geomagnetic models. The static core field, its secular variation and the lithospheric field are all in good agreement with previously published magnetic field models.

Map illustration of vertical down component of the modelled core field acceleration (i.e. second derivative in time) from 2002.0 to 2005.5 calculated at the Earth's reference radius (a=6371.2km).
Vertical down component of the modelled core field acceleration (i.e. second derivative in time) from 2002.0 to 2005.5 calculated at the Earth's reference radius (a=6371.2km).

Downloads

FileFormatSizeDateContent
GRIMM_splines.zipZIP36kBJun 2007GRIMM Gauss Coefficients SH degrees 1 to 14.
GRIMM_2003.5.zipZIP147kBAug 2007GRIMM Gauss Coefficients for the static core field, its secular variation and acceleration in 2003.5.
GJI-07-0346-R.pdfPDF5.1MBFeb 2008GRIMM - The GFZ Reference Internal Magnetic Model based on vector satellite and observatory data (GJI, 2008).

Contact

Profile photo of  Dr. Monika Korte

Dr. Monika Korte
Geomagnetism

Behlertstra├če 3a
Building K 3, room 116
14467 Potsdam
tel. +49 331 288-1268