Radial Evolution of Multi-MeV Relativistic Electrons during Enhancement Events at Geostationary Orbit

In this work, we utilized a dataset of 60 relativistic electron enhancement events measured at geostationary orbit (GEO) to compare against in situ
measurements from the Van Allen Probes mission and study the radial response of outer belt fluxes and the correlation between the fluxes at GEO
and those at lower L-shells closer to the Earth. The enhancement events occurred between 1 October 2012 and 31 December 2017 and were identified
using Geostationary Operational Environmental Satellite (GOES) 15 > 2 MeV.  We compare the events with fluxes measured by the Van Allen probes Energetic Particle, Composition and Thermal Plasma Suite Relativistic Electron-Proton Telescope (ECT-REPT) between 2.5 < L < 6.0 at the entire range of
energies between E = 1.8 MeV through E = 7.6 MeV. We found that the response of the radiation belts during enhancement events is very homogeneous for L > 4.0 and extremely similar for L > 5.0 at all studied energies. Post-enhancement maximum fluxes show a remarkable correlation for all L > 4.0 for all energy channels, with a maximum correlation at 4.2 MeV. We further studied the characteristic solar wind forcing leading to those relativistic electron enhancement events and characterized the L-dependent response according to the geomagnetic driver of the event.