Study of a TGF Associated With an Elve Using Extremely Low Frequency Electromagnetic Waves.

A terrestrial gamma‐ray flash (TGF) associated with an Elve was recently reported by the Atmosphere‐Space Interactions Monitor (ASIM) (Neubert et al., 2020, https://doi.org/10.1126/science.aax3872). An extremely low frequency electromagnetic field pulse coinciding with this event was detected by two stations of our World Extremely Low Frequency (ELF) Radiolocation Array (WERA) project from a distance of more than 10,000 km. The recorded signal allowed us to radiolocate the source, determine its polarity, and calculate the charge moment of the associated atmospheric discharge. Our analysis shows that this TGF was associated with a powerful discharge that had a positive polarity and the charge moment p ≈ 125 C·km. Plain Language Summary: Observation of a terrestrial gamma‐ray flash (TGF, a flash of high‐energy X‐rays and gamma rays from a thunderstorm region into space) and an associated Elve phenomenon in the lower ionosphere was reported by the Atmosphere‐Space Interactions Monitor onboard the International Space Station. An extremely low frequency (below 300 Hz) electromagnetic field pulse from the TGF‐associated lightning was detected with magnetic antennas from a distance of more than 10,000 km by the Hylaty and Patagonia extremely low frequency (ELF) stations of our World ELF Radiolocation Array (WERA) project. In this paper we use these measurements to determine the charge moment of the TGF source lightning discharge, not provided by higher frequency measurements. Key Points: WERA radiolocation system uses magnetic antennas to detect ELF radio waves from powerful lightning discharges occurring all over the worldASIM registered the first Terrestrial Gamma‐ray Flash associated with an Elve. We provide fundamental physical parameters of the sourceELF impulses can be used to radiolocate lightning discharges associated with TGFs and estimate their polarity and charge moment [ABSTRACT FROM AUTHOR]