Spectral Observations of Optical Emissions Associated with Terrestrial Gamma‐Ray Flashes

Matthias Heumesser*, Olivier Chanrion, Torsten Neubert, Hugh Christian, Krystallia Dimitriadou, Francisco J. Gordillo‐Vazquez, Alejandro Luque, Francisco Javier Pérez‐Invernón, Richard J. Blakeslee, Nikolai Østgaard, Victor Reglero, Christoph Köhn

*Corresponding author for this work

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    Abstract

    The Atmosphere-Space Interactions Monitor measures Terrestrial Gamma-Ray Flashes (TGFs) simultaneously with optical emissions from associated lightning activity. We analyzed optical measurements at 180–230, 337, and 777.4 nm related to 69 TGFs observed between June 2018 and October 2019. All TGFs are associated with optical emissions and 90% of them are at the onset of a large optical pulse, suggesting that they are connected with the initiation of current surges. A model of photon delay induced by cloud scattering suggests that the sources of the optical pulses are from 0.7 ms before to 4.4 ms after the TGFs, with a median of −10 ± 80 µs, and 1–5 km below the cloud top. The pulses have rise times comparable to lightning but longer durations. Pulse amplitudes at 337 nm are ∼3 times larger than at 777.4 nm. The results support the leader-streamer mechanism for TGF generation.
    Original languageEnglish
    Article number2020GL090700
    JournalGeophysical Research Letters
    Volume48
    Issue number4
    Number of pages10
    ISSN0094-8276
    DOIs
    Publication statusPublished - 2021

    Bibliographical note

    This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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