Abstract
This study investigates the energy spectrum of electron microbursts
observed by the Fo-
cused Investigation of Relativistic Electron Burst: Intensity, Range,
and Dynamics II (FIREBIRD-
II) CubeSats. FIREBIRD-II is a pair of CubeSats, launched in January
2015 into a low
Earth orbit, that focus on studying electron microbursts. High
resolution electron data
from FIREBIRD-II consists of 5 differential energy channels between 200
keV and 1 MeV
and a >1 MeV integral channel. This covers an energy range
that has not been well stud-
ied from low Earth orbit with good energy and time resolution. This
study aims to im-
prove understanding of the scattering mechanism behind electron
microbursts by inves-
tigating their spectral properties and their relationship to the
equatorial electron pop-
ulation under different geomagnetic conditions. Microbursts are
identified in the region
of the North Atlantic where FIREBIRD only observes electrons in the
bounce loss cone.
The electron flux and exponential energy spectrum of each microburst is
calculated us-
ing a FIREBIRD instrument response modeled in GEANT4 (GEometry ANd
Tracking)
and compared with the near equatorial electron spectra measured by the
Van Allen Probes.
Microbursts occurring when the AE index is enhanced tend to carry more
electrons with
relatively higher energies. The microburst scattering mechanism is more
efficient at scat-
tering electrons with lower energies, however the difference in
scattering efficiency be-
tween low and high energy is reduced during periods of enhanced AE.