| Terrestrial gamma-ray flashes (TGFs) are bursts of high-energy photons originating from the
Earth’s atmosphere in association with thunderstorm activity [e.g., Briggs et al., JGR, 118,
3805, 2013]. TGFs are associated with initial propagation stages of intracloud lightning,
which represent the most frequent type of lightning discharges [e.g., Cummer et al., GRL, 42,
7792, 2015, and references therein]. TGFs are known to be produced inside common
thunderclouds [e.g., Splitt et al., JGR, 115, A00E38, 2010] typically at altitudes ranging from
10 to 14 km [e.g., Cummer et al., GRL, 41, 8586, 2014]. The global TGF occurrence rate
is estimated to be 400,000 per year concerning TGFs detectable by Fermi-GBM
(Gamma ray Burst Monitor) [Briggs et al., 2013], but detailed analysis of satellite
measurements [Østgaard et al., JGR, 117, A03327, 2012] and theoretical studies
[Celestin et al., JGR, 120, 10712, 2015] suggest that it cannot be excluded that TGFs
represent a part of a regular process taking place during the propagation of lightning
discharges.
It is important to assess the risk induced by TGFs for airline passengers and crews on
board aircraft approaching thunderstorms. Dwyer et al. [JGR, 115, D09206, 2010] have
estimated that if an aircraft were to find itself in the source electron beam giving rise to a
TGF, passengers and crews might receive effective radiation doses above the regulatory limit
depending on the beam diameter. Moreover, Tavani et al. [Nat. Hazards Earth Syst. Sci., 13,
1127, 2013] concluded that TGF-associated neutrons produced by photonuclear reactions
would cause serious hazard on the aircraft avionics. In this work, we will present detailed
simulation-based estimations of effective doses received by humans that would be
irradiated by TGFs for various production altitudes and distances from the TGF
source. |