Library of simulated gamma-ray glows and application to previous
Gamma-Ray Glows (GRGs) are high energy radiation originating from
thunderclouds, in the MeV energy regime, with typical duration of
seconds to minutes, and sources extended over several to tens of square
kilometers. GRGs have been observed from detectors placed on ground,
inside aircraft and on balloons. In this paper, we present a general
purpose Monte-Carlo model of GRG production and propagation. This model
is first compared to a model from Zhou et al. (2016) relying on another
Monte-Carlo framework, and small differences are observed. We then have
built an extensive simulation library, made available to the community.
This library is used to reproduce five previous gamma-ray glow
observations, from five airborne campaigns: balloons from Eack et al.
(1996b), Eack et al. (2000); and aircrafts from ADELE (Kelley et al.,
2015), ILDAS (Kochkin et al., 2017) and ALOFT (Østgaard et al., 2019).
Our simulation results confirm that fluxes of cosmic-ray secondary
particles present in the background at a given altitude can be enhanced
by several percent (MOS process), and up to several orders of magnitude
(RREA process) due to the effect of thunderstorms’ electric fields, and
explain the five observations. While some GRG can be explained purely by
the MOS process, E-fields significantly larger than E_th (the RREA
threshold) are required to explain the strongest GRGs observed. Some of
the observations also came with in-situ electric field measurements,
that were always lower than E_th , but may not have been obtained from
regions where the glows are produced. This study supports the claim that
kilometer-scale E-fields magnitudes of at least the level of E_th must
be present inside some thunderstorms.