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Abstract Energetic electron precipitation into Earth's atmosphere is an important process for radiation belt dynamics and magnetosphere‐ionosphere coupling. The most intense form of such precipitation is microbursts—short‐lived bursts of precipitating fluxes detected on low‐altitude spacecraft. Due to the wide energy range of microbursts (from sub‐relativistic to relativistic energies) and their transient nature, they are thought to be predominantly associated with energetic electron scattering into the loss cone via cyclotron resonance with field‐aligned intense whistler‐mode chorus waves. In this study, we show that intense sub‐relativistic microbursts may be generated via electron nonlinear Landau resonance with very oblique whistler‐mode waves. We combine a theoretical model of nonlinear Landau resonance, equatorial observations of intense very oblique whistler‐mode waves, and conjugate low‐altitude observations of <200 keV electron precipitation. Based on model comparison with observed precipitation, we suggest that such sub‐relativistic microbursts occur by plasma sheet (0.1 − 10 keV) electron trapping in nonlinear Landau resonance, resulting in acceleration to ≲200 keV energies and simultaneous transport into the loss cone. The proposed scenario of intense sub‐relativistic (≲200 keV) microbursts demonstrates the importance of very oblique whistler‐mode waves for radiation belt dynamics.
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Lightning-induced relativistic electron precipitation from the inner radiation belt
Abstract The Earth’s radiation belts are maintained by a number of acceleration, loss and transport mechanisms, and the electron fluxes at any given time are highly variable. Microbursts, which are rapid (sub-second) bursts of energetic electrons entering the atmosphere from the magnetosphere, are one of the key loss mechanisms controlling radiation belt fluxes. Such rapid bursts are typically observed from the outer radiation belt and driven by interactions with whistler mode chorus waves, but they can also occur in the inner belt and slot region, driven by lightning-generated whistlers. This lightning-induced electron precipitation is typically observed at 10s–100s keV, but here we present direct observations of this phenomenon at MeV energies. This unveils a coupling between near-Earth processes, such as lightning, and radiation belt processes, such as relativistic electron microbursts, bridging the gap between Earth weather and space weather.
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- Award ID(s):
- 2123253
- PAR ID:
- 10547837
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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