Simulations of Plasmasphere Refilling Observed by the Van Allen Probes

We present four cases of plasmasphere refilling observed by the Van Allen Probes under ideal conditions. Two strong storms during 15 - 19 March 2013 (7- peak Kp-index) and 1 - 6 October 2013 (8- peak Kp-index) produce severe erosion of the plasmasphere in the midnight and dusk MLT sectors respectively. Two moderate storms during 18 - 25 November 2015 (5 peak Kp-index) and 16 - 20 April 2016 (4 peak Kp-index) diminish the extent of the plasmasphere in the noon and dawn MLT sectors respectively. In each case, geomagnetic activity peaks and subsides over the course of 24 hours followed by a long quiet period of several days. Measurements of magnetospheric equatorial electron density by the Van Allen Probes show a two-stage increase in density at apogee near L = 6 for early-times in the first 48 hours after the storm and late-times in the next 48 hours during refilling. A semi-empirical treatment of the contributing rate of ionospheric outflow into the plasmasphere performs best after significant erosion but reduces in efficacy at the end of the recovery period. We simulate the location of the plasmapause with a physics-based model of E x B transport to provide global context for the local changes in density observed by the Van Allen Probes along each spacecraft's trajectory.