1,1,1,- 1University of Bergen, Department of Physics and Technology, Norway (rabeah.khan@student.uib.no)
- 2NASA Marshall Space Flight Center, Huntsville, AL, USA
Recent data from the ALOFT flight campaign have confirmed the lightning activity and high energy particle acceleration interconnection. The results comprised the discovery of a large fraction of low-brightness Terrestrial Gamma-ray Flashes (TGFs), signifying that the bright flashes observed from space account for only a small fraction of these events. Many of these weak TGFs, undetectable from space, are associated with a prominent 337.1 nm optical pulse and differ from those detected from space by the lack of 777.4 nm dominated lightning discharges [Mezentsev et al. 2025]. Brightness down to 1012 photons at a source reference altitude of 15 km have been observed and there is no theoretical reason that opposes the existence of dimmer TGFs [Bjørge-Engeland et al. 2024; Fuglestad et al. 2025].
Although detection of individual events would be prevented due to instrument sensitivity, this project aims to tackle this obstacle by stacking the gamma-ray signals in timeframes prior to the emergence of blue dominated lightning discharges. If a substantial population of dim TGFs below the sensitivity threshold for ALOFT exists, it should appear as an enhancement in the cumulated gamma-ray signal.
This presentation focus on the stacking analysis of the gamma-ray data detected by ALOFT in association with the blue dominated lightning discharges. We will present the methodology, the data selection strategy and the preliminary results.
References:
A. Mezentsev et al. (2025). New Class of Gamma-Ray Flashes Indicate Gamma Glow Rest through Fast Streamer Discharge. https://doi.org/10.5194/egusphere-egu25-15838
I. Bjørge-Engeland et al. (2024). Evidence of a New Population of Weak Terrestrial Gamma—Ray Flashes Observed from Aircraft Altitude. Geophysical Research Letters, 51, https://doi.org/10.1029/2024GL110395
A. Fuglestad et al. (2025). The source brightness distribution of Terrestrial Gamma-ray Flashes from the ALOFT flight campaign. Submitted to JGR: Atmospheres
How to cite: Khan, R., Marisaldi, M., Bjørge-Engeland, I., Østgaard, N., and Quick, M.: Gamma-ray production associated with blue dominated lightning discharges in glowing thunderclouds observed by ALOFT, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21097, https://doi.org/10.5194/egusphere-egu26-21097, 2026.
