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
Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA, 90095, USA.
Department of Earth and Planetary Science, School of Science, The University of Tokyo, Tokyo, Japan.
Nat Commun. 2022 Mar 25;13(1):1611. 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.
来自地球外辐射带的高能电子沉降加热高层大气并改变其化学性质。沉降通量强度通常使用来自高空赤道航天器的输入进行建模，它决定了辐射带对大气的能量贡献以及空间 - 大气耦合的强度。通过与等离子体波的适度快速扩散相互作用产生电子沉降的经典准线性理论预测，沉降电子通量不能超过被困在辐射带中的电子通量，这为电子沉降设定了一个明显的上限。在此，我们从低空卫星观测结果表明，约100 keV的电子沉降率常常超过这个明显的上限。我们证明，这种超快沉降是由电子与强等离子体波的非线性相互作用引起的，而这种相互作用此前并未纳入辐射带模型。超快沉降的高发生率表明，它对于辐射带通量建模和空间 - 大气耦合建模都很重要。
