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| Main Authors: | , |
|---|---|
| Format: | Recurso digital |
| Language: | English |
| Published: |
Zenodo
2026
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| Subjects: | |
| Online Access: | https://doi.org/10.5281/zenodo.19425537 |
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Table of Contents:
- <p>We analyze the temporal distribution of 4,130 Terrestrial Gamma-ray Flashes (TGFs)<br>detected by the Fermi Gamma-ray Burst Monitor (2008–2018) as a function of Local<br>Solar Time (LST). The distribution is highly non-uniform (χ² = 579.6, df = 23, p ≈<br>0). TGF occurrence peaks at 16–17h LST (pre-dusk), with a rate of 256.7 events/hour<br>at dusk (17–20h) versus 87.2 events/hour during midday (10–14h) — a ratio of 2.9×.<br>A secondary enhancement occurs at dawn (4–7h, 174.3 events/hour). This temporal<br>pattern correlates with the passage of the solar terminator, the boundary between<br>the sunlit and shadowed hemispheres. We examine concurrent data from ionospheric<br>soundings (Juliusruh foF2, 2023), geomagnetic indices (Kp, 94-year record), and tran-<br>sient luminous events (Eurosprite catalog, 2009–2013). The ionospheric electron den-<br>sity gradient (dfoF2/dt) peaks at dawn and dusk transitions. We propose that the<br>enhanced TGF rate at the solar terminator reflects a systematic variation in upper-<br>atmosphere electromagnetic permeability at the day-night boundary, and discuss im-<br>plications for future measurements of local spacetime curvature oscillations.</p>