A simulation study on the electric field spectral dependence of thunderstorm ground enhancements and gamma ray glows

Abstract : We have done a thorough simulation analysis on the variability of the photon spectra produced with (due to Relativistic Runaway Electron Avalanche—RREA) and without (Modification of Spectra) the avalanche multiplication process. Despite some measurements obviously showing a variability of the spectra, numerous theoretical studies consider RREA spectrum independent on the electric field. However, analytical calculations by Cramer et al. (2014) have shown that RREA spectrum under low electric fields is not constant and stops being exponential. Using the Relativistic Electron Avalanche Model code, we model various layouts of the electric field configuration and study the predicted photon spectra. The primary focus of the present paper is to study the photon energy spectra, as gamma rays are more often observed by ground-based detectors. The simulation analysis of photon spectra potentially can help to deduce electric fields in thunderclouds.