A lightning discharge producing a beam of relativistic electrons into space

Strong electric fields associated with lightning generate brief (∼1 ms) but intense Terrestrial Gamma‐ray Flashes (TGFs), detected by spacecrafts. A few events are thought to be the signature of a relativistic electron beam escaping the atmosphere, which is distinguishable from a TGF since the lightning discharge is along the geomagnetic field line from the spacecraft, rather than below. We refer to this event herein as a ‘Terrestrial Energetic‐electron Flash’ (TEF), and present the first TEF with associated discharge. The TEF was detected by the Gamma‐ray Burst Monitor aboard the Fermi satellite, and is correlated with a lightning discharge detected by three Stanford University AWESOME ELF/VLF receivers, a Duke University ULF receiver, and by the GLD360 lightning geolocation network. The discharge, nearly simultaneous with the generated electrons, was of intense peak current and of positive polarity, and with a modest total charge transfer, similar to TGF‐associated discharges.