A novel view of gamma-ray glows from the ALOFT 2023 flight campaign
- 1University of Bergen, Department of Physics and Technology, Bergen, Norway (martino.marisaldi@uib.no)
- 2NASA Marshall Space Flight Center, Huntsville, USA
- 3Department of Atmospheric Science, Earth System Science Center, University of Alabama in Huntsville, Huntsville, USA
- 4U.S. Naval Research Laboratory, Washington DC, USA
- 6NASA Goddard Space Flight Center, Greenbelt, USA
- *A full list of authors appears at the end of the abstract
The Airborne Lightning Observatory for FEGS and TGFs (ALOFT) was a field campaign targeted at Terrestrial Gamma-ray Flashes (TGFs) and gamma-ray glows from thunderclouds. The campaign was successfully carried out during July 2023, for a total of 60 flight hours in the Gulf of Mexico and the Caribbean. The scientific payload was flown on a NASA ER-2 research aircraft, capable to fly at 20 km altitude above thunderclouds. The payload included a suite of gamma-ray detectors spanning four orders of magnitude dynamic range in flux, and a complete suite of instruments for the characterisation of the electrical and optical activity, and the thundercloud environment. A key asset of the mission was the real-time downlink of gamma-ray count rates, which enabled the immediate identification of gamma-ray glowing regions. The pilot was then instructed to turn and pass over the same glowing region to explore its spatial extension and duration.
ALOFT resulted in the detection of hundreds of gamma-ray glows, anticipating a revolution in our understanding of the phenomenon. Thunderclouds were observed to glow for hours and over several thousands of square kilometers, making glows a much more pervasive phenomenon than previously reported. Glows show significant time variability from seconds down to millisecond time scale, suggesting a relation to short transients such as TGFs more complex than previously thought. Glows are observed in association with the overpass of active convective cores, 20-25 km in size, yet their time variability and intensity modulation suggest a more complex spatial structure.
These observations challenge the current view of glows as quasi-stationary phenomena related to relatively stable electrification conditions. The observed glows show highly dynamic temporal and spatial structures and are closely related to the development phases of active thunderclouds. These observations call for a rethinking of the assumptions at the basis of current modeling efforts.
N. Østgaard1, T. Lang 2, M. Marisaldi1, J. E. Grove4, M. Quick 2, H. Christian 3, C. Schultz2, R. Blakeslee2, I. Adams6, R. Kroodsma6, G. Heymsfield6, A. Mezentsev1, D. Sarria1, I. Bjørg Engeland 1, A. Fuglestad 1, N. Lehtinen1, K. Ullaland1, S. Yang1, B. Hasan Qureshi1, J. Søndergaard1, B. Husa1, D. Walker3, D. Shy4, M. Bateman3, D. Mach13, P. Bitzer3, M. Fullekrug7, M. Cohen8, M. Stanley9, S. Cummer10, J. Montanya11, M. Pazos12, C. Velosa5, O. van der Velde11, Y. Pu10, P. Krehbiel9, J. A. Roncancio11, J. A. Lopez11, M. Urbani 11, A. Santos 5 1 Department of Physics and Technology, University of Bergen, Norway 2 NASA Marshall Space Flight Center, Huntsville, USA 3 Department of Atmospheric Science, Earth System Science Center, University of Alabama in Huntsville, Huntsville, USA 4 U.S. Naval Research Laboratory, Washington DC, USA 5 Universidad Nacional de Colombia, Columbia 6 NASA Goddard Space Flight Center, Greenbelt, USA 7 University of Bath, UK 8 Georgia Institute of Technology, USA 9 New Mexico Institute of Mining and Technology, USA 10 Duke University, USA 11 Polytechnic University of Catalonia, Spain 12 Instituto de Ciencias de la Atmosfera y Cambio Climatico, UNAM, Mexico 13 Universities Space Research Association, Huntsville, Alabama, USA
How to cite: Marisaldi, M., Østgaard, N., Lang, T. J., Grove, J. E., Quick, M., Christian, H., Schultz, C. J., Blakeslee, R., Adams, I. S., Kroodsma, R. A., Heymsfield, G. M., Mezentsev, A., Sarria, D., Bjørge-Engeland, I., Fuglestad, A., Lehtinen, N., Ullaland, K., Yang, S., Qureshi, B. H., and Søndergaard, J. and the ALOFT team: A novel view of gamma-ray glows from the ALOFT 2023 flight campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7927, https://doi.org/10.5194/egusphere-egu24-7927, 2024.
