Press release from AGU highlights new Birkelandsenter discoveries about gamma rays from thunderstorms
A host of new discoveries about the mysterious gamma rays emanating from thunderclouds were unveiled by Birkeland Center leader Nikolai Østgaard during his talk on Tuesday, December 10 at the American Geophysical Union (AGU) Fall Meeting 2019 in San Francisco. AGU's fall meeting is the largest of its kind in the world and attracts about 25,000 participants from around the world each year. Prof. Østgaard presented findings based on observations made by the ASIM instrument – an ESA project with IFT/UiB and several European partners – which was sent to the International Space Station in April 2018.
Scientists accidentally discovered terrestrial gamma rays (TGFs) in 1994. Subsequent research found that TGFs occur within milliseconds of lightning, but their cause remained a mystery. Researchers working with ASIM now report that they have identified where the powerful gamma rays originate. They also report the first ASIM detection of an electron beam created by a TGF, the time of occurrence of TGFs relative to lightning, and the first detection of a TGF and an elf – a fast, expanding ring of light produced during thunderstorms at an altitude of 90 to 100 kilometers.
AGUs press release gives more details on the research results.
The new disoveries are also presented in three new publications in the scientific journals Science and Journal of Geophysical Research:
- Nikolai Østgaard et al.: First ten months of TGF observations by ASIM. Journal of Geophysical Research: Atmospheres, 2019.
- David Sarria et al.: The First Terrestrial Electron Beam Observed by The Atmosphere-Space Interactions Monitor. Journal of Geophysical Research: Space Physics, 2019.
- Torsten Neubert et al.: A Terrestrial Gamma-ray Flash and Ionospheric Ultraviolet Emissions Powered by Lightning. Science, 2019.