Upper panel: validation of the modeled GCR-induced ion-pair production rates (solid line) against balloon measurements performed by Neher (1971) (dots, see Banjac et al. 2019a, for further validation). Lower panel: CR-induced atmospheric ionization for scenario 1 (quiescent Sun) and scenario 2 (GLE05) displayed as black and green curves, respectively. As can be seen, differences of up to three orders of magnitude occur.