Fig. 3
From: Sequential modelling of the Earth’s core magnetic field
On the left: maps of the difference (Chaos-6)-(CE), radial comp. of the SV, at the Earth’s Surface, for years 2011.75 (top) and 2013.75 (bottom). On the right: maps of the corresponding SV radial component for the CE model, at the same epochs. Local positive and negative maxima in 2011.75 change sign in 2013.75. This is the signature of a spike of acceleration between these two epochs. Models are truncated at degree 12