Electron dropout echoes induced by interplanetaryshock: Van Allen Probes observations

Abstract:

On 23 November 2012, the responses of energetic particles at around geosynchronous
orbit have been recorded by both Van Allen Probes and GOES satellites
when an interplanetary shock interacts with the Earth’s magnetosphere.
A sudden dropout event of high-energy (> 300keV ) electron flux, associated
with a typical substorm-like electron injection with energy less than 300
keV, have been observed. The electron flux dropout peaks at 500keV-1MeV,
in which more than 80% of the electrons disappeared from the drift shell.
Both Van Allen Probes A and B observed sharp electron flux dropout with
clear energy dispersion signitures. The repeating flux dropout and recovery
signitures, or “dropout echoes”, indicate a drifting electron “dropout” with
a limited initial spatial range. The azimuthal range of the dropout region is
estimated to be counterclockwise from LT  1300 to LT  0100 according
to the dispersion signitures observed. Based on both the Van Allen Probes
and GOES observations, we conclude that the shock induced electron dropout
is probably not caused by the magnetopause shadowing effect. Further, we

suggested that the electron dropout can be produced by inward or outward
drift shell splitting due to the interplanetary shock related magnetospheric
reconfiguration.