Fig. 5

Geographical differences between 2015.0 epoch models. Differences in the B r components, when comparing the following: a the ASM-V 2015.0 IGRF candidate and VFM 2015.0 auxiliary models, b the VFM 2015.0 and N-VFM 2015.0 auxiliary models, c the ASM-V 2015.0 IGRF candidate and official 2015.0 IGRF models, and d the VFM 2015.0 auxiliary and official 2015.0 IGRF models; all at Earth’s surface (i.e., at reference radius a = 6371.2 km)