Observation of a Terrestrial Electron Beam during the tropical cyclone Joaninha in March 2019
Abstract
Terrestrial Gamma-ray Flashes (TGFs) are short (~10 us to ~2 ms) flashes of high energy (< 40 MeV) photons, produced by thunderstorms, between 10 and 16 km altitude (at least for TGFs detectable from space). When interacting with the atmosphere, the photons produce electrons (through Compton scattering and pair production) and positrons (through pair production), of which a small fraction is able to escape the atmosphere [1,2]. The escaping electrons/positrons are then bounded to Earth's magnetic field lines and can travel large distances inside the ionosphere and the magnetosphere. This phenomenon is called a Terrestrial Electron Beam (TEB).
The Atmosphere-Space Interactions Monitor (ASIM), dedicated to the study of TGF and associated events, started to operate in June 2018. ASIM contains an optical instrument (MMIA) made of micro-cameras and photometers, as well the Modular X and Gamma-ray Sensor (MXGS) for high energy radiation. MXGS is composed of two detectors : the low energy detector (LED, 50 keV to 400 keV) and the High Energy detector (HED, 300 keV to 40 MeV). ASIM could detect several TEB events, and this presentation will be focused on the March 24th, 2019 event. The TEB originated from rainbands produced by the tropical cyclone Joaninha, in the Indian Ocean, close to Madagascar. The LED instrument was turned on, which permitted to detect the low energy part (<400 keV) of a TEB spectrum for the first time. References: [1] J. R., Dwyer, B. W., Grefenstette and D. M. Smith High-energy electron beams launched into space by thunderstorms Geophysical Research Letters, 2008. [2] B. E. Carlson T. Gjesteland N. Østgaard Terrestrial gamma-ray flash electron beam geometry, fluence, and detection frequency Journal of Geophysical Research (Space Physics), 2011.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMAE33A3130K
- Keywords:
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- 3304 Atmospheric electricity;
- ATMOSPHERIC PROCESSES;
- 3324 Lightning;
- ATMOSPHERIC PROCESSES;
- 4301 Atmospheric;
- NATURAL HAZARDS