Exploring the potential of aerial and balloon-based observations in the study of terrestrial gamma ray flashes

Abstract

Abstract. Recently presented measurements of terrestrial gamma ray flashes (TGFs) above thunderstorms on board aircraft and weather balloons introduce viable alternatives which could help to overcome limitations inherent in satellite-based observations, such as gamma ray attenuation by the atmosphere and large distance between TGF source and detectors. This study explores the potential and implications of measuring TGFs using aircraft and weather balloons. Utilizing Monte Carlo simulations with the MCNP6 tool, the spatial distributions, fluences, and energy spectra of photons, electrons, and neutrons generated by TGFs are assessed at altitudes of 5 to 50 km. The results indicate that TGFs originating at lower altitudes produce narrower beams compared to those at higher altitudes, suggesting that weather balloons may be more effective for high-altitude TGFs, such as those associated with summer thunderstorms or thunderstorms in tropical regions, whereas staffed aircraft might be more suitable for low-altitude TGFs originating in temperate regions or in winter thunderstorms. Features of the photon and electron energy spectra, such as maximum energy and the presence of 511 keV photons, can help estimate the radial distance from the TGF axis. Expected photon fluences from TGFs reach up to 1000 cm −2 , with electron fluences reaching up to 100 cm −2 , depending on the TGF's brightness. Neutron fluences are notably lower, up to 1 cm −2 . These findings underscore the potential of aerial and balloon-based measurements in providing critical insights into TGFs and their detection, addressing the limitations of current satellite observations.