Chorus Acceleration of Relativistic Electrons in Extremely Low L‐Shell During Geomagnetic Storm of August 2018

Abstract

Abstract Based on data from the Van Allen Probes and ZH‐1 satellites, relativistic electron enhancements in extremely low L‐shell regions (reaching L∼3) were observed during August 2018 major geomagnetic storm (minimum Dst≈−190 nT). Contrary to what occurs in the outer belt, such an intense and deep electron penetration event is rare and more interesting. Strong whistler‐mode (chorus and hiss) waves, with amplitudes 81–126 pT, were also observed in the extremely low L‐shell simultaneously (reaching L∼2.5) where the plasmapause was suppressed. The bounce‐averaged diffusion coefficient calculations support that the chorus waves can play a significantly important role in diffusing and accelerating the 1–3 MeV electrons even in such low L‐shells during storms. This is the first time that the electron acceleration induced by chorus waves in the extremely low L‐shell region is reported. This new finding will help to deeply understand the electron acceleration process in radiation belt physics.

Keywords

• relativistic electron flux enhancement
• chorus wave acceleration
• magnetosphere storm
• in extremely low L‐shells
• quasi‐linear diffusion