A candidate secular variation model for IGRF-12 based on Swarm data and inverse geodynamo modelling

Earth, Planets and Space

Table 2 Statistics of the Swarm data used in this study

Data type	Number	Mean residual (nT)	rms misfit (nT)
ASM F mid-lat.	307885	0.17	3.12
ASM F high-lat.	197411	-0.67	4.26
total F			3.61
VFM B _r	307885	-0.04	4.14
VFM B _θ	307885	-0.14	6.02
VFM B _φ	307885	2.80	6.85
total B			5.78
total	1428951		5.11

All data are Level-1b products (National Space Institute, T.U.o.D. 2013). On the third column from the left, the mean residual refers to the average difference between a given measurement and its prediction by the initial model centered at epoch t _c=2014.3 (see text for details). The mean aims at detecting a possible bias between measurements and model predictions. The rightmost column is the root-mean-squared misfit of the initial model predictions to the data. The overall root-mean-squared misfit σ ^o is equal to 5.11 nT