Rapid Loss of Relativistic Electrons by EMIC Waves in the Outer Radiation Belt Observed by Arase, Van Allen Probes, and the PWING Ground Stations

Abstract

There has been increasing evidence for pitch angle scattering of relativistic electrons by electromagnetic ion cyclotron (EMIC) waves. Theoretical studies have predicted that the loss time scale of MeV electrons by EMIC waves can be very fast, suggesting that MeV electron fluxes rapidly decrease in association with the EMIC wave activity. This study reports on a unique event of MeV electron loss induced by EMIC waves based on Arase, Van Allen Probes, and ground‐based network observations. Arase observed a signature of MeV electron loss by EMIC waves, and the satellite and ground‐based observations constrained spatial‐temporal variations of the EMIC wave activity during the loss event. Multisatellite observation of MeV electron fluxes showed that ~2.5‐MeV electron fluxes substantially decreased within a few tens of minutes where the EMIC waves were present. The present study provides an observational estimate of the loss time scale of MeV electrons by EMIC waves.

Radiation Dose During Relativistic Electron Precipitation Events at the International Space Station

“…Recently, REP events have been considered one of the fundamental loss processes of outer radiation belt electrons (Kubota et al, 2015;Kurita et al, 2018;Lorentzen et al, 2000;Millan et al, 2002). A basic understanding of REP events thus contributes to predicting the dynamic variation of the radiation belts, which is a major target of space weather forecasts.…”

Rapid Precipitation of Relativistic Electron by EMIC Rising‐Tone Emissions Observed by the Van Allen Probes

“…There have been many reports of simultaneous observations of EMIC waves and the precipitation of relativistic electrons (Hirai et al, 2018;Kurita et al, 2018;Miyoshi et al, 2008;Rodger et al, 2008Rodger et al, , 2015. There have been many reports of simultaneous observations of EMIC waves and the precipitation of relativistic electrons (Hirai et al, 2018;Kurita et al, 2018;Miyoshi et al, 2008;Rodger et al, 2008Rodger et al, , 2015.…”

“…In recent years, EMIC waves are thought to be more effective on the precipitation of relativistic electrons. There have been many reports of simultaneous observations of EMIC waves and the precipitation of relativistic electrons (Hirai et al, 2018;Kurita et al, 2018;Miyoshi et al, 2008;Rodger et al, 2008Rodger et al, , 2015. The quasi-linear theory is widely used for estimating the influence of the wave-particle interaction (Summers, 2005) and derives the timescale of the interaction as minutes to hours (Li et al, 2014;Ni et al, 2015;Summers et al, 2007;Ukhorskiy et al, 2010;Usanova et al, 2014).…”

Prompt Response of the Dayside Magnetosphere to Discrete Structures Within the Sheath Region of a Coronal Mass Ejection

“…Similar signatures were observed by Zhu et al (2020) and shown to be a result of nonlinear interaction between rising tone EMIC waves and MeV electrons, which can scatter particles toward the loss cone via phase trapping. Kurita et al (2018) also observed scattering of lower pitch angle MeV electrons in association with EMIC wave activity. This event suggests that while short-lived, these structured EMIC wave bursts can have rapid nonlinear scattering effects on energetic electrons, as demonstrated theoretically by Omura and Zhao (2012).…”