Dependence of Relativistic Electron Precipitation in the Ionosphere on EMIC Wave Minimum Resonant Energy at the Conjugate Equator

Abstract

Electromagnetic ion cyclotron (EMIC) waves are mostly left-hand-polarized waves observed in the 0.1-5 Hz range in the inner magnetosphere. These waves are generated near the equator by the temperature anisotropy of ring current ions either injected from the plasma sheet during geomagnetic storms or substorms or transversely heated by dayside magnetopause compression (Anderson et al., 1992;McCollough et al., 2010;Usanova et al., 2010). In a plasma containing H + and He + ions, EMIC waves can be generated in two distinctive bands below and above the helium gyrofrequency (Stix, 1962;Summers & Thorne, 2003;Zhang et al., 2016).Electron pitch-angle scattering by EMIC waves has been proposed as an important mechanism of relativistic electron precipitation (REP) into the atmosphere (

Hot Plasma Effects on Electron Resonant Scattering by Electromagnetic Ion Cyclotron Waves

“…The EMIC wave intensity is often sufficiently high to provide fast electron scattering in quasi‐linear diffusion or (Drozdov et al., 2017; Ni et al., 2015) nonlinear resonant interactions (Albert & Bortnik, 2009; Grach & Demekhov, 2020; Kubota et al., 2015). The good correlation between low‐altitude measurements of relativistic electron precipitation and near‐equatorial EMIC wave measurements supports the hypothesis that EMIC waves play a key role in relativistic electron losses from the Earth’s radiation belts (Blum et al., 2015; Capannolo, Li, Ma, Shen, et al., 2019; Zhang et al., 2021).…”

“…It has been reported, however, that hot plasma effects for observed EMIC waves only result in an increase in the energy of resonant electrons (J. Cao et al., 2017; Chen et al., 2019). But these estimates were focused on EMIC wave frequencies corresponding to the peak wave intensity, whereas low‐intensity higher‐frequency part of EMIC waves may be more promising to scatter sub‐MeV electrons (Bashir et al., 2022; Denton et al., 2019; Zhang et al., 2021). This study aims to reveal and model the hot plasma effects for relativistic electron scattering by observed EMIC waves.…”

Role of Ducting in Relativistic Electron Loss by Whistler‐Mode Wave Scattering

“…manuscript submitted to JGR: Space Physics al., 2012; Gao et al, 2015;Sorathia et al, 2017) or cyclotron resonance with electromagnetic ion cyclotron waves (Thorne & Kennel, 1971;Usanova et al, 2014;Blum et al, 2015;Ma et al, 2015;Mourenas et al, 2016;Shprits et al, 2016;Grach & Demekhov, 2020;Zhang et al, 2021).…”

“…Thus, although dayside waves can occasionally (during geomagnetically active times) attain wave-normal angles near the resonance cone and scatter  1 E MeV electrons toward the loss cone (Agapitov et al, 2018;Artemyev et al, 2015Artemyev et al, , 2016, the predominant low-intensity and mildly oblique character of dayside chorus renders it, on average, ineffective in relativistic electron scattering. Thus, up to now relativistic electron loss is typically attributed to two other mechanisms: magnetopause shadowing (Gao et al, 2015;Sorathia et al, 2017;Turner et al, 2012) or cyclotron resonance with electromagnetic ion cyclotron waves (Blum et al, 2015;Grach & Demekhov, 2020;Ma et al, 2015;Mourenas et al, 2016;Shprits et al, 2016;Thorne & Kennel, 1971;Usanova et al, 2014;Zhang et al, 2021).…”

Weak Turbulence and Quasilinear Diffusion for Relativistic Wave-Particle Interactions Via a Markov Approach

“…Numerous observations have shown the prevalence of high-amplitude electromagnetic whistler-mode and ion-cyclotron waves in the Earth's inner magnetosphere (Cattell et al, 2008;Cully et al, 2008;Breneman et al, 2011;Kellogg et al, 2011;Wilson et al, 2011;Hendry et al, 2019;Tyler et al, 2019;Zhang et al, 2019;Zhang et al, 2021), such as are responsible for local changes in the energy and pitch-angle of radiation belt electrons. These high "nonlinear" wave amplitudes cast some doubt on the applicability of the quasilinear theory in such cases.…”