Radiation belt electron dynamics at low L (<4): Van Allen Probes era versus previous two solar cycles

Long‐term (>2 solar cycles) measurements reveal that MeV electron fluxes, solar wind speed, and geomagnetic activity have been extremely low during this current solar cycle, including years before and during the Van Allen Probes era. This study examines solar wind speed, the geomagnetic storm index (Dst), >2 MeV electrons at geostationary orbit, and ~2 MeV electrons across various L shells measured by Solar Anomalous Magnetospheric Particle Explorer in low Earth orbit (LEO) and by the Van Allen Probes/Relativistic Electron and Proton Telescope (REPT) in a geotransfer‐like orbit; the latter measurements are normalized to LEO based on comparison with Colorado Student Space Weather Experiment/Relativistic Electron and Proton Telescope integrated little experiment (REPTile) measurements in LEO. The average ratio of REPTile/REPT varies in a systematic manner with L, ~16% at L = 2.7, decreasing with L and reaching ~0.7% at L = 4.7, and increasing again with L though with greater uncertainty. We show that there have been no ~2 MeV electron enhancements inside L ~ 2.6 since 2006, prior to which numerous penetrations of ~2 MeV electrons into L