EMBRACE-AGS-Seed: Powerful Gamma-Ray and Radio-Frequency Emissions from Thunderstorms

Terrestrial Gamma-ray Flashes (TGFs) are high energy emissions related to thunderstorm processes. The scientific community has been able to observe TGFs through satellite and ground-based sensors, but the exact mechanisms by which TGFs are formed and their relationship to lightning are still uncertain. This award will merge large datasets to address several open scientific questions about TGFs. The societal impact of the project is through the better understanding of the production of TGFs and how to detect them, which is especially important for aircraft crew and passengers who are subjected to high-energy radiation. This award also represents a first-time NSF award for an early career PI and will help to establish connections between academia and industry. A graduate student will also be trained and educated under the award. This study will take advantage of the combination of massive datasets from ground-based radio observations of lightning/TGFs and space-based observations of TGFs, which became available recently. Data from the Fermi Gamma-ray Burst Monitor (Fermi-GBM) satellite mission and the Atmosphere-Space Interactions Monitor (ASIM) instrument on the International Space Station will be combined with ground-based lightning network data from the Earth Networks Total Lightning Network (ENTLN) and Vaisala’s Global Lightning Detection Network (GLD360) to address three main questions: 1) What is the relationship of TGF high-energy photons launched to the space and their radio signatures seen from the ground, 2) What are the properties of the radio emissions from multi-pulsed TGFs, and 3) What is the geographical and seasonal variability of TGFs and lightning? This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.