Fig. 5

Field intensity (top), its rate of change (middle) and its acceleration (bottom) at Earth’s surface in 2015. Units are \(\mu T=10^3\hbox {nT}\), nT/year and \(\hbox {nT/year}^2\) , respectively. Map projection is Hammer-Aitoff
Field intensity (top), its rate of change (middle) and its acceleration (bottom) at Earth’s surface in 2015. Units are \(\mu T=10^3\hbox {nT}\), nT/year and \(\hbox {nT/year}^2\) , respectively. Map projection is Hammer-Aitoff