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The Energy Spectra of Electron Microbursts Between 200 keV and 1 MeV
  • +4
  • Arlo Johnson,
  • Mykhaylo Shumko,
  • John Sample,
  • Brady A Griffith,
  • David Klumpar,
  • Harlan E. Spence,
  • J Bernard Blake
Arlo Johnson
Montana State University, Montana State University

Corresponding Author:arlo.johnson@montana.edu

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Mykhaylo Shumko
NASA's Goddard Space Flight Center, NASA's Goddard Space Flight Center
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John Sample
Montana State University, Montana State University
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Brady A Griffith
Montana State University, Montana State University
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David Klumpar
Montana State University, Montana State University
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Harlan E. Spence
University of New Hampshire, University of New Hampshire
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J Bernard Blake
The Aerospace Corporation, The Aerospace Corporation
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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.
Nov 2021Published in Journal of Geophysical Research: Space Physics volume 126 issue 11. 10.1029/2021JA029709