When it comes to testing the predictive secular variation, comparisons between models and observatory data appear to be more discriminant than intercomparisons between models.
Here we report on comparisons between candidate models and observatory and satellite data that were carried out as part of the evaluation process of IGRF-11.
There is also some evidence of periodic, possibly annual, signals in these data, too. Figure 8 Mean and root mean square of the residuals between parent model and input observatory data.
Future authors who are interested in improving the position corresponding to the POGO magnetic field measurements may wish to use more sophisticated magnetic field models and include observatory data, which will allow to solve additionally for the remaining external field component.
An alternative perspective is given in the article by Chulliat and Thebault who describe attempts to compare the candidate models directly with satellite and observatory data.
This shows in black predictions for the rate of change of the axial dipole in units of nT/yr from the GRIMM-2 time-dependent field model (constrained by CHAMP satellite and observatory data between 2001.0 and 2009.5) along with formal error bars, including an extrapolation back to 2000.2 and forward to 2010.8.
Left: 1-D conductivity model obtained from inversion of satellite and observatory data (Püthe et al. 2015).
The main field model for 2015 and the SV model were derived from a parent model built from a combination of Swarm satellites and observatory data.
We derived a core magnetic field model spanning the 2004.87 2005.94 period from CHAMP satellite and observatory data.
These models are extracted from a spherical harmonic 'parent model' derived from vector and scalar magnetic field data from satellite and observatory sources.
