Rebuilding of the Earth’s Outer Electron Belts During the 9 October 2012 and 17 March 2013 Geomagnetic Storms

Abstract:

The build up of ~1 MeV electrons near geosynchronous orbit observed during the recovery period of the 9 October 2012 geomagnetic storm is well modeled by computing test-particle trajectories in MHD magnetospheric model fields. Comparison between data and model results shows that the recovery of ~1 MeV radiation belt electrons near geosynchronous is mainly due to global convection and dipolarization associated injections from the plasma sheet [Kress et al., GRL, 2014]. Energetic particle measurements made with the Van Allen Probes spacecraft during this geomagnetic storm suggest that transport of electrons with energies up to ~2 MeV is driven by convection well inside of geosynchronous orbit, in a region where radiation belt transport is usually treated as diffusive. The general build up of outer belt electrons during the 17 March 2013 geomagnetic storm is also well modeled with test-particle trajectories in global MHD magnetospheric model fields. Rapid transport of plasma sheet electrons may provide a seed population for local acceleration mechanisms, resulting in the observed enhancements in 2-6 MeV outer radiation belt flux.