Superfast precipitation of energetic electrons in the radiation belts of the Earth

• Published in: Nature communications Vol. 13; no. 1; pp. 1611 - 8
• Main Authors: Zhang, Xiao-Jia, Artemyev, Anton, Angelopoulos, Vassilis, Tsai, Ethan, Wilkins, Colin, Kasahara, Satoshi, Mourenas, Didier, Yokota, Shoichiro, Keika, Kunihiro, Hori, Tomoaki, Miyoshi, Yoshizumi, Shinohara, Iku, Matsuoka, Ayako
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25.03.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/525/869; 704/525/868; Altitude; Atmosphere; Atmospheric models; Chemical precipitation; Chemical properties; Coupling; Electron flux; Electron precipitation; High altitude; Humanities and Social Sciences; Jupiter; Low altitude; Magnetic storms; multidisciplinary; Outer radiation belt; Plasma waves; Radiation; Radiation belts; Satellite observation; Science; Science (multidisciplinary); Spacecraft; Storms; Upper atmosphere; Waves
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-29291-8

Energetic electron precipitation from Earth’s outer radiation belt heats the upper atmosphere and alters its chemical properties. The precipitating flux intensity, typically modelled using inputs from high-altitude, equatorial spacecraft, dictates the radiation belt’s energy contribution to the atmosphere and the strength of space-atmosphere coupling. The classical quasi-linear theory of electron precipitation through moderately fast diffusive interactions with plasma waves predicts that precipitating electron fluxes cannot exceed fluxes of electrons trapped in the radiation belt, setting an apparent upper limit for electron precipitation. Here we show from low-altitude satellite observations, that ~100 keV electron precipitation rates often exceed this apparent upper limit. We demonstrate that such superfast precipitation is caused by nonlinear electron interactions with intense plasma waves, which have not been previously incorporated in radiation belt models. The high occurrence rate of superfast precipitation suggests that it is important for modelling both radiation belt fluxes and space-atmosphere coupling. Energetic electron densities in the radiation belt increases during geomagnetic storms. Here, the authors show oblique whistler mode waves enhance electron losses and create strong fluxes of about 100 keV electrons precipitating into the atmosphere, that should be considered in radiation belt models.