Estimation of Radiation Doses Delivered by Terrestrial Gamma Ray Flashes Within Leader‐Based Production Models

Abstract

AbstractWith a typical production altitude of ∼12 km, Terrestrial Gamma ray Flash (TGF) sources are close to commercial flight altitudes, and these events could potentially be an unforeseen exposure to ionizing radiation for aircraft passengers and crews. Dwyer et al. (2010) estimated the dose that a TGF could produce, and showed that TGFs in principle could be an additional non‐negligible factor to the exposure for aircraft passengers. The regulations for aircrew protection against radiation, only consider the radiation of galactic and solar origin (Bottollier‐Depois et al., 2012; ICRP, 2007). Other possible sources of exposure, such as TGFs, are not yet considered, mainly because of the lack of reliable data on possible dose levels and on the probability for an airplane to be in the vicinity of such an event. In order to improve the evaluation of the TGF exposure level and associated risks, and as there is still a divergence of opinion about the exact source mechanisms, we present calculations of doses produced by high‐energy electrons in TGF sources, within two different lightning leader‐based production models: (1) a pure lightning leader model and (2) considering further avalanches in a homogeneous electric field region. We find that although the doses from photon and secondary electron beams are weak, the dose potentially received by passengers inside the TGF electron source regions may be very high (>20 mSv). The results reported in the present paper call for a need to perform a thorough risk assessment including the probability for an aircraft to be in a TGF source region.