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The Dynamics of the Inner Boundary of the Outer Radiation Belt During Geomagnetic Storms
Author(s) -
Shi Xiaofei,
Ren Jie,
Zong Q. G.
Publication year - 2020
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2019ja027309
Subject(s) - van allen radiation belt , plasmasphere , geomagnetic storm , van allen probes , physics , electron , earth's magnetic field , atomic physics , flux (metallurgy) , computational physics , magnetosphere , magnetic field , plasma , nuclear physics , chemistry , quantum mechanics , organic chemistry
We investigate the shapes of the inner boundary of the outer radiation belt during different geomagnetic storm phases using energetic electron observations from Van Allen Probes. The case of two consecutive but isolated storms in April 2016 shows that (a) the inner boundary, as a function of L shell and energy, exhibits a “V‐shaped” form with the energetic electrons showing a kappa‐like energy spectrum (electron flux steeply falling with increasing energies), whereas it is in a “S‐shaped” form as the energetic electrons show a reversed energy spectrum (electron flux going up with increasing energies from hundreds of keV to ∼1 MeV); (b) the boundary is abruptly transformed from S to V shape during the storm main phase and retains in V shape for several days until it evolves into S shape during the late recovery phase. The main statistical results from 37 isolated geomagnetic storms between 2013 and 2017 present that (a) the more SYM‐H drops, the closest to Earth the transition from V to S shape starts, with a linear correlation coefficient of ∼0.7; (b) the minimum energy at which the transition starts is between 100 and 550 keV (typically, less than 250 keV); (c) the transition from V to S shape typically occurs in the plasmasphere.