The Mag.num core field model as a parent for IGRF-13, and the recent evolution of the South Atlantic Anomaly

Earth, Planets and Space

Table 2 Statistics of the satellite and observatory data used to obtain the Mag.num model

Type	Latitudes	Coordinates	N	Mean (nT)	rms (nT)
Satellite
X	LM	SM	266258	0.023	2.936
Y	LM	SM	266258	\(-\)0.045	3.091
Z	LM	SM	266258	0.215	3.215
X	HL	NEC	773163	\(-\)1.892	37.740
Y	HL	NEC	773163	1.380	44.129
Z	HL	NEC	773163	\(-\)0.727	14.084
Additional for Euler angle estimation
X	LM	SM	226619	0.173	3.989
Y	LM	SM	226619	\(-\)0.125	3.695
Z	LM	SM	226619	\(-\)0.186	3.784
Observatories
X	LM	SM	516072	0.184	3.634
Y	LM	SM	516072	\(-\)0.136	3.737
Z	LM	SM	516072	\(-\)0.038	5.107
X	HL	NEC	114321	\(-\)0.541	10.432
Y	HL	NEC	114321	0.220	9.098
Z	HL	NEC	114321	\(-\)0.408	12.923

N is the number of input data after data selection. The mean of the residuals and the rms misfit are given separately for the X, Y and Z field components. LM stands for low and mid latitudes, HL for high latitudes. SM stands for solar magnetic and NEC for geocentric North East Centre