Quantifying the size and duration of a microburst-producing chorus
region on 5 December 2017
Abstract
Microbursts are impulsive (<1s) injections of electrons (few
keV to >MeV) from the outer radiation belt into the
atmosphere, primarily caused by nonlinear scattering by chorus waves.
Although attempts have been made to quantify their contribution to outer
belt electron loss, the uncertainty in the overall size and duration of
the microburst region is typically large, so that their contribution to
outer belt loss is uncertain. We combine datasets that measure chorus
waves (Van Allen Probes (RBSP), Arase, ground-based VLF stations) and
microburst (>30 keV) precipitation (FIREBIRD II and AC6
CubeSats, POES/MetOp) to determine the size of the microburst-producing
chorus source region beginning on 5 December 2017. We show that the
lower/upper limits on the long-lasting (~30 hours)
microburst precipitation region is 4 to 8 MLT and 2 to 8.5 L. We
conclude that microbursts likely represent a major loss source of outer
radiation belt electrons for this event.