Fig. 1.

Measured and simulated ultra-relativistic electron flux from September 2012 to May 2014. The time series of Kp during this interval is shown in a. b The 3.4 MeV electron flux measured with the REPT instrument on Probes A and B during this time interval. c, d The simulated electron flux at a fixed energy of 3.4 MeV produced using a radial diffusion model applying the empirical radial diffusion coefficients from D_LL[B & A]²⁴ and D_LL[Ozeke]⁴, respectively. Both these radial diffusion coefficient models are functions of the Kp values shown in a. Similar measured and simulated electron flux results are also shown at a fixed energy of 4.2 MeV in e, f, and g, and at a fixed energy of 5.2 MeV in h, i, and j. The location of the plasmapause derived from the Carpenter and Anderson²¹ model is also over-plotted on the measured electron flux illustrated by the white curve in b, e, and h