Night-Side Relativistic Electron Precipitation Bursts in the Outer Radiation Belt: Insights From ELFIN and THEMIS

Electromagnetic whistler-mode waves play a crucial role in the acceleration and precipitation of radiation belt electrons. Statistical surveys of wave characteristics suggest that these waves preferentially scatter and precipitate relativistic electrons on the day side. In contrast, the night-side region has traditionally been associated primarily with electron acceleration. Recent low-altitude observations, however, reveal relativistic electron precipitation in the night-side region. In this paper, we present statistical surveys of nightside relativistic electron losses due to intense precipitation bursts. We demonstrate that such bursts are associated with storm time substorm injections and speculate on the role of injections in creating conditions favorable for relativistic electron precipitation. The exponential decay of the precipitating spectra at high energies is fitted with a model function suitable for evaluating the impact of relativistic precipitation on the ionosphere. We also discuss how the maximum precipitating energies and the correlation with injections indicate that these bursts are likely caused by relativistic electron scattering by ducted whistler-mode waves.