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Abstract 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.
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The principal role of chorus ducting for night-side relativistic electron precipitation
Night-side chorus waves are often observed during plasma sheet injections, typically confined around the equator and thus potentially responsible for precipitation of ≲ 100𝑘𝑒𝑉 electrons. However, recent low-altitude observations have revealed the critical role of chorus waves in scattering relativistic electrons on the night-side. This study presents a night-side relativistic electron precipitation event induced by chorus waves at the strong diffusion regime, as observed by the ELFIN CubeSats. Through event-based modeling of wave propagation under ducted or unducted regimes, we show that a density duct is essential for guiding chorus waves to high latitudes with minimal damping, thus enabling the strong night-side relativistic electron precipitation. These findings underline both the existence and the important role of density ducts in facilitating night-side relativistic electron precipitation.
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- Award ID(s):
- 2025706
- PAR ID:
- 10539394
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Geophysical research letters
- ISSN:
- 1944-8007
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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