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EDITORIAL article
Front. Astron. Space Sci. , 11 February 2025
Sec. Space Physics
Volume 12 - 2025 | https://doi.org/10.3389/fspas.2025.1559238
This article is part of the Research Topic The Loss and Acceleration Mechanisms of Energetic Electrons in the Earth’s Outer Radiation Belt View all 10 articles
Editorial on the Research Topic
The loss and acceleration mechanisms of energetic electrons in the Earth’s outer radiation belt
The Earth’s outer radiation belt is occupied by different energy electrons (10 s keV – 10 s MeV). The outer radiation belt during geomagnetic storms is extremely variable due to different loss and acceleration mechanisms. Losses mechanisms of electrons mainly include magnetopause shadowing with subsequent enhanced outward radial transport and scattering into the atmospheric loss cones (drift or bounce) via wave-particle interactions with electron cyclotron harmonic (ECH) waves, chorus waves, plasmaspheric hiss, and electromagnetic ion cyclotron (EMIC) waves, etc. Acceleration mechanisms of electrons mainly include local acceleration via gyroresonant interactions with whistler mode chorus waves and inward radial diffusion by ultralow-frequency (ULF) waves. The solar wind and magnetospheric processes have important effects on the evolution of electrons in the outer radiation belt. Other magnetized planets with radiation belts also experience above physical mechanisms.
This Research Topic, “The Loss and Acceleration Mechanisms of Energetic Electrons in the Earth’s Outer Radiation Belt,” aims in advancing the understanding of the loss and acceleration mechanisms of radiation belt electrons and improve the capability to model and forecast the evolution of electrons in the outer radiation belt. This Research Topic collected 9 research articles to address a wide range of topics in the loss and acceleration mechanisms of the electrons in the outer radiation belt.
Yu et al. investigated the influences of latitude-dependent wave power spectrum on the scattering effects of chorus waves on electrons. Compared with the latitude-dependent model, traditional latitudinally constant model introduces great errors in the diffusion coefficients, especially for electrons with small to intermediate pitch angles. Their simulations demonstrate that the latitude distribution of wave power spectrum plays an important role in controlling the dynamics of radiation belt electrons.
Foster et al. examined the consequences of an upstream motion of the chorus wave generation region based on Van Allen Probes observations and nonlinear theory. The findings underscore the importance of considering source region motion in models to enhance the accuracy of predictions related to radiation belt electron behavior.
He et al. investigated the long-duration transpolar arcs (TPA) observed by Fengyun-3D and Defense Meteorological Satellite Program (DMSP) satellites on 17 January 2019, an exceptionally quiet period (AE<30 nT). The TPA initially appeared at the poleward boundary of the auroral oval in the dawn sector and gradually migrated towards the dusk sector. The observations underscore the complex field and particle dynamics in the high-latitude reconnection region and the twisted tail plasma sheet.
Chen et al. studied the ultra-relativistic electron dynamics during continuous geomagnetic storm events based on Van Allen Probe observations. Compared to an isolated geomagnetic storm, electrons are accelerated to higher energies and larger flux levels in continuous geomagnetic storm events. These results are helpful to understand the dynamics of ultra-relativistic electrons in the Earth’s outer radiation belt during continuous geomagnetic storm events.
Silva et al. introduced a new method called “Invariant Matching” to quantify adiabatic motions. They presented adiabatic motion at different storm phases using the TS05 magnetic field model. This new method can be applied to both outer radiation belt and ring current populations. To remove the influence of adiabatic motion, the observed electron fluxes are usually transferred to phase space densities. Silva et al. reviewed the calculation steps of phase space densities with different implementation options and showed the calculation results. Their analysis reveals that variations in magnetic field models can lead to significant discrepancies in PSD estimations.
Liu et al. examined how variations in wave normal angles, as well as the velocities and temperatures of proton ring and shell distributions, influence the growth rates of magnetosonic (MS) waves based on a full wave dispersion relation solver, the study. These results provide new insights into the excitation of MS waves in Earth’s magnetosphere.
Hosseini et al. developed a backward test particle numerical model to investigate energetic electrons distribution interacted with coherent whistler mode waves. Nonlinear interaction features are shown in the simulation results, suggesting the important role of nonlinear phase trapping in driving the amplification of whistler mode waves. These results contribute to a more comprehensive understanding of radiation belt dynamics.
Chakraborty et al. investigated the near-equatorial pitch angle distributions (PADs) of relativistic electrons in the outer belt based on 7 years’ observations of Van Allen Probe B. The distribution of three PADs types (pancake, butterfly, flattop) are presented by calculating a pitch angle anisotropy index (PAI). Their results suggest that a simplified formula can capture PADs of outer radiation belt relativistic electrons.
CT: Writing–review and editing. ZX: Writing–original draft. HZ: Writing–review and editing. XL: Writing–review and editing.
The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.
The authors are grateful to the contributors and reviewers of the papers included in this Frontiers Research Topic. They also thank the Frontiers editorial team for their valuable support and assistance.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
The author(s) declare that no Generative AI was used in the creation of this manuscript.
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
Keywords: outer radiation belt, wave-particle interactions, chorus waves, magnetoionic waves, phase space density
Citation: Tang C, Xiang Z, Zhao H and Liu X (2025) Editorial: The loss and acceleration mechanisms of energetic electrons in the Earth’s outer radiation belt. Front. Astron. Space Sci. 12:1559238. doi: 10.3389/fspas.2025.1559238
Received: 12 January 2025; Accepted: 20 January 2025;
Published: 11 February 2025.
Edited and reviewed by:
Joseph E. Borovsky, Space Science Institute (SSI), United StatesCopyright © 2025 Tang, Xiang, Zhao and Liu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Zheng Xiang, eGlhbmd6aGVuZ0B3aHUuZWR1LmNu
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.
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