Fig. 13

The top four maps show the radial component of the primary ionospheric magnetic field from the CIY4 model at Earth’s surface during vernal equinox centered on noon local time for 06, 12, 18, and \(00\,\hbox {UT}\). The bottom four maps are similar to the top, but from the Swarm L2 Dedicated Ionospheric Field Inversion (DIFI) product (see Chulliat et al. 2016). Solid/dashed contour lines indicate positive/negative contours in increments of \(5\,\hbox {nT}\). A value of \(F_{10.7}=100.0\times 10^{-22}\,\mathrm{W}/\mathrm{m}^2/\mathrm{Hz}\) was used for evaluation