DEMETER Satellite Observations of Lightning-Induced Electron Precipitation Events

Electromagnetic (EM) waves generated by lightning strokes in the Earth’s atmosphere are important phenomena regarding the loss of energetic electrons from the Van Allen radiation belts. During lightning-induced electron precipitation (LEP) events, these EM waves interact with trapped radiation belt electrons, decreasing their pitch angle, and causing their eventual loss in the atmosphere. LEP events in satellite data are characterized by a sudden increase in wave intensity over a wide range of frequencies, accompanied by an increase in the precipitating electron flux. We develop a semi-automatic procedure to detect LEP events in the wave and particle burst mode data measured by the DEMETER satellite between 2004 and 2010. In total, we detected more than 400 events, mostly above the U.S. East Coast. The identified events occurred mainly at L-shells between approximately 2 and 3.75, and extended up to energies of about 200 keV. We show an annual variation in VLF wave intensities and precipitating energetic electron fluxes comparable with the annual variation of lightning occurrence. Finally, we estimated total precipitating electron fluxes and wave intensities based on the average LEP properties and lightning occurrence rate, showing that the individual isolated LEP events appear to be insufficient to explain the observed summer-winter differences in the precipitating electron fluxes above the U.S. region.