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Van Allen Probes Measurements of Energetic Particle Deep Penetration Into the Low L Region ( L < 4) During the Storm on 8 April 2016
Author(s) -
Zhao H.,
Baker D. N.,
Califf S.,
Li X.,
Jaynes A. N.,
Leonard T.,
Kanekal S. G.,
Blake J. B.,
Fennell J. F.,
Claudepierre S. G.,
Turner D. L.,
Reeves G. D.,
Spence H. E.
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2017ja024558
Subject(s) - electron , plasma sheet , penetration (warfare) , physics , van allen probes , electric field , convection , proton , atomic physics , geomagnetic storm , electron precipitation , substorm , plasma , magnetosphere , van allen radiation belt , solar wind , nuclear physics , mechanics , operations research , quantum mechanics , engineering
Using measurements from the Van Allen Probes, a penetration event of tens to hundreds of keV electrons and tens of keV protons into the low L shells ( L < 4) is studied. Timing and magnetic local time (MLT) differences of energetic particle deep penetration are unveiled and underlying physical processes are examined. During this event, both proton and electron penetrations are MLT asymmetric. The observed MLT difference of proton penetration is consistent with convection of plasma sheet protons, suggesting enhanced convection during geomagnetic active times to be the cause of energetic proton deep penetration during this event. The observed MLT difference of tens to hundreds of keV electron penetration is completely different from tens of keV protons and cannot be well explained by inward radial diffusion, convection of plasma sheet electrons, or transport of trapped electrons by enhanced convection electric field represented by the Volland‐Stern model or a uniform dawn‐dusk electric field model based on the electric field measurements. It suggests that the underlying physical mechanism responsible for energetic electron deep penetration, which is very important for fully understanding energetic electron dynamics in the low L shells, should be MLT localized.