Fig. 1

First data group: fragment of Previous dataset. a Plot of the difference \(\Delta F_{\mathrm{P}}\) between the Earth’s magnetic field total intensity measured by the ASM and that reconstructed using the VFM. Local time of the ascending node of the satellite is reported on the right axis in red; b map of LT distribution of \(\Delta F_{\mathrm{P}}\). Previous data are not corrected for the disturbance correlated with Sun incidence angle; values consist of decimated low-resolution magnetic measurements recorded from May 15, 2014, to September 12, 2014, by Swarm A satellite