Flickering gamma-ray flashes, the missing link between gamma glows and TGFs

N Østgaard; A Mezentsev; M Marisaldi; J E Grove; M Quick; H Christian; S Cummer; M Pazos; Y Pu; M Stanley; D Sarria; T Lang; C Schultz; R Blakeslee; I Adams; R Kroodsma; G Heymsfield; N Lehtinen; K Ullaland; S Yang; B Hasan Qureshi; J Søndergaard; B Husa; D Walker; D Shy; M Bateman; P Bitzer; M Fullekrug; M Cohen; J Montanya; C Younes; O van der Velde; P Krehbiel; J A Roncancio; J A Lopez; M Urbani; A Santos; D Mach

doi:10.1038/s41586-024-07893-0

Flickering gamma-ray flashes, the missing link between gamma glows and TGFs

Nature. 2024 Oct;634(8032):53-56. doi: 10.1038/s41586-024-07893-0. Epub 2024 Oct 2.

Authors

N Østgaard¹, A Mezentsev², M Marisaldi^{3

4}, J E Grove⁵, M Quick⁶, H Christian⁷, S Cummer⁸, M Pazos⁹, Y Pu⁸, M Stanley¹⁰, D Sarria¹¹, T Lang⁶, C Schultz⁶, R Blakeslee⁶, I Adams¹², R Kroodsma¹², G Heymsfield¹², N Lehtinen¹¹, K Ullaland¹¹, S Yang¹¹, B Hasan Qureshi¹¹, J Søndergaard¹¹, B Husa¹¹, D Walker⁷, D Shy⁵, M Bateman⁷, P Bitzer⁷, M Fullekrug¹³, M Cohen¹⁴, J Montanya¹⁵, C Younes¹⁶, O van der Velde¹⁵, P Krehbiel¹⁰, J A Roncancio¹⁵, J A Lopez¹⁵, M Urbani¹⁵, A Santos¹⁶, D Mach¹⁷

Affiliations

¹ Department of Physics and Technology, University of Bergen, Bergen, Norway. Nikolai.Ostgaard@uib.no.
² Department of Physics and Technology, University of Bergen, Bergen, Norway. Andrey.Mezentsev@uib.no.
³ Department of Physics and Technology, University of Bergen, Bergen, Norway. Martino.Marisaldi@uib.no.
⁴ Astrophysics and Space Science Observatory, National Institute for Astrophysics, Bologna, Italy. Martino.Marisaldi@uib.no.
⁵ US Naval Research Laboratory, Washington, DC, USA.
⁶ NASA Marshall Space Flight Center, Huntsville, AL, USA.
⁷ Department of Atmospheric Science, Earth System Science Center, University of Alabama in Huntsville, Huntsville, AL, USA.
⁸ Duke University, Durham, NC, USA.
⁹ Instituto de Ciencias de la Atmosfera y Cambio Climático, UNAM, Mexico City, Mexico.
¹⁰ New Mexico Institute of Mining and Technology, Socorro, NM, USA.
¹¹ Department of Physics and Technology, University of Bergen, Bergen, Norway.
¹² NASA Goddard Space Flight Center, Greenbelt, MD, USA.
¹³ University of Bath, Bath, UK.
¹⁴ Georgia Institute of Technology, Atlanta, GA, USA.
¹⁵ Polytechnic University of Catalonia, Barcelona, Spain.
¹⁶ Universidad Nacional de Colombia, Bogota, Colombia.
¹⁷ Universities Space Research Association, Huntsville, AL, USA.

PMID: 39358523
DOI: 10.1038/s41586-024-07893-0

Abstract

Two different hard-radiation phenomena are known to originate from thunderclouds: terrestrial gamma-ray flashes (TGFs)¹ and gamma-ray glows². Both involve an avalanche of electrons accelerated to relativistic energies but are otherwise different. Glows are known to last for one to hundreds of seconds, have moderate intensities and originate from quasi-stationary thundercloud fields^2-5. TGFs exhibit high intensities and have characteristic durations of tens to hundreds of microseconds^6-9. TGFs often show a close association with an emission of strong radio signals^10-17 and optical pulses^18-21, which indicates the involvement of lightning leaders in their generation. Here we report unique observations of a different phenomenon, which we call flickering gamma-ray flashes (FGFs). FGFs resemble the usual multi-pulse TGFs^22-24 but have more pulses and each pulse has a longer duration than ordinary TGFs. FGF durations span from 20 to 250 ms, which reaches the lower boundary of the gamma-ray glow duration. FGFs are radio and optically silent, which makes them distinct from normal TGFs. An FGF starts as an ordinary gamma-ray glow, then suddenly increases exponentially in intensity and turns into an unstable, 'flickering' mode with a sequence of pulses. FGFs could be the missing link between the gamma-ray glows and conventional TGFs, whose absence has been puzzling the atmospheric electricity community for two decades.