Statistical Properties of Electron Curtain Precipitation Estimated with
AeroCube-6
Abstract
Curtain precipitation are a recently discovered stationary, persistent,
and latitudinally narrow electron precipitation phenomenon in low Earth
orbit. Curtains are observed over consecutive passes of the dual
AeroCube-6 CubeSats while their in-track lag varied from a fraction of a
second to 65 seconds, with dosimeters that are sensitive to
> 30 keV electrons. This study uses the AeroCube-6 mission
to quantify the statistical properties of 1,634 curtains observed over
three years. We found that many curtains are narrower than 10 kilometers
in the latitudinal direction with 90\% narrower than 20
kilometers, corresponding to a few hundred kilometer radial size at the
magnetic equator. We examined the magnetic local time and geomagnetic
dependence of curtains. We found that curtains are observed in the
late-morning and pre-midnight magnetic local times, with a higher
occurrence rate at pre-midnight, and curtains are observed more often
during times of enhanced Auroral Electrojet. We found a few curtains in
the bounce loss cone region above the north Atlantic, whose electrons
were continuously scattered for at least 6 seconds. Such observations
suggest that continuous curtain precipitation may be a significant loss
of > 30 keV electrons from the magnetosphere into the
atmosphere, possibly scattered by a parallel direct current electric
field.