Formation of Energetic Electron Butterfly Distributions by Magnetosonic Waves via Landau Resonance

TitleFormation of Energetic Electron Butterfly Distributions by Magnetosonic Waves via Landau Resonance
Publication TypeJournal Article
Year of Publication2016
AuthorsLi, J, Ni, B, Ma, Q, Xie, L, Pu, Z, Fu, S, Thorne, RM, Bortnik, J, Chen, L, Li, W, Baker, DN, Kletzing, CA, Kurth, WS, Hospodarsky, GB, Fennell, JF, Reeves, GD, Spence, HE, Funsten, HO, Summers, D
JournalGeophysical Research Letters
Paginationn/a - n/a
Date Published04/2016
Keywordsbutterfly distributions; energetic electrons; Landau resonance; magnetosonic waves; Radiation belt; Van Allen Probes
AbstractRadiation belt electrons can exhibit different types of pitch angle distributions in response to various magnetospheric processes. Butterfly distributions, characterized by flux minima at pitch angles around 90°, are broadly observed in both the outer and inner belts and the slot region. Butterfly distributions close to the outer magnetospheric boundary have been attributed to drift shell splitting and losses to the magnetopause. However, their occurrence in the inner belt and the slot region has hitherto not been resolved. By analyzing the particle and wave data collected by the Van Allen Probes during a geomagnetic storm, we combine test particle calculations and Fokker-Planck simulations to reveal that scattering by equatorial magnetosonic waves is a significant cause for the formation of energetic electron butterfly distributions in the inner magnetosphere. Another event shows that a large-amplitude magnetosonic wave in the outer belt can create electron butterfly distributions in just a few minutes.
URLhttp://doi.wiley.com/10.1002/2016GL067853http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2016GL067853
DOI10.1002/2016GL067853
Short TitleGeophys. Res. Lett.


Page Last Modified: April 13, 2016