Rebuilding of the Earth\textquoterights outer electron belt during 8-10 October 2012

Geomagnetic storms often include strong magnetospheric convection caused by sustained periods of southward interplanetary magnetic field. During periods of strong convection, the Alfv\ en layer, which separates the region of sunward convection from closed drift shells, is displaced earthward allowing plasma sheet particles with energies in the hundreds of keV direct access inside of geosynchronous. Subsequent outward motion of the Alfv\ en boundary and adiabatic energization during storm recovery traps plasma sheet electrons on closed drift shells providing a seed population for the outer radiation belts. In situ observations of the 8\textendash10 October 2012 geomagnetic storm and MHD test particle simulations illustrate the morphology of this process. Data and modeling results support the conclusion that recovery of ~ 1 MeV electrons at geosynchronous is mainly due to global convection and dipolarization associated injections from the plasma sheet.