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Van Allen Probes observations linking radiation belt electrons to chorus waves during 2014 multiple storms
Author(s) -
Liu Si,
Xiao Fuliang,
Yang Chang,
He Yihua,
Zhou Qinghua,
Kletzing C. A.,
Kurth W. S.,
Hospodarsky G. B.,
Spence H. E.,
Reeves G. D.,
Funsten H. O.,
Blake J. B.,
Baker D. N.,
Wygant J. R.
Publication year - 2015
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2014ja020781
Subject(s) - hiss , chorus , van allen radiation belt , van allen probes , physics , electron , geomagnetic storm , computational physics , astrophysics , geophysics , magnetosphere , earth's magnetic field , atomic physics , nuclear physics , magnetic field , plasma , quantum mechanics , art , literature
During 18 February to 2 March 2014, the Van Allen Probes encountered multiple geomagnetic storms and simultaneously observed intensified chorus and hiss waves. During this period, there were substantial enhancements in fluxes of energetic (53.8–108.3 keV) and relativistic (2–3.6 MeV) electrons. Chorus waves were excited at locations L = 4–6.2 after the fluxes of energetic were greatly enhanced, with a lower frequency band and wave amplitudes ∼20–100 pT. Strong hiss waves occurred primarily in the main phases or below the location L = 4 in the recovery phases. Relativistic electron fluxes decreased in the main phases due to the adiabatic (e.g., the magnetopause shadowing) or nonadiabatic (hiss‐induced scattering) processes. In the recovery phases, relativistic electron fluxes either increased in the presence of enhanced chorus or remained unchanged in the absence of strong chorus or hiss. The observed relativistic electron phase space density peaked around L ∗ = 4.5, characteristic of local acceleration. This multiple‐storm period reveals a typical picture that chorus waves are excited by the energetic electrons at first and then produce efficient acceleration of relativistic electrons. This further demonstrates that the interplay between both competing mechanisms of chorus‐driven acceleration and hiss‐driven scattering often occurs in the outer radiation belts.