Figure 3. RBSPICE observations of proton fluxes during 2015 and the corresponding distributions of reversed proton energy spectra. (a) Dst and AE indices, (b-d) 90° pitch angle proton fluxes at energies of ~44.7 keV, ~81.6 keV, and ~268.9 keV, respectively, (e) occurrence rate of the reversed proton energy spectrum, (f) the proton energy of flux maximum, (g) the proton energy of flux minimum, and (h) the ratio of proton flux maximum to minimum. The white solid lines in (b-e) indicate the plasmapause location.