Geolocation of terrestrial gamma-ray flash source lightning

Abstract

Terrestrial gamma-ray flashes (TGFs) are impulsive (similar to 1 ms) but intense sources of gamma-rays associated with lightning activity and typically detected via low orbiting spacecrafts. We present the first catalog of precise (< 30 km error) TGF source locations, determined via ground-based detection of ELF/VLF radio atmospherics (or sferics) from lightning discharges, which enables precise geolocation of lightning locations. We present the distribution of source-tonadir distances, established due to effects of Compton scattering on the escaping photons. We find that TGFs occur in coincidence with the lightning discharge, but with a few ms variance, and that a detectable sferic at long distances is nearly always present. The properties of TGF-associated sferics and their connection to multiple-peak TGFs are highly variable and inconsistent, and are classified into two categories.