Lightning-Induced Energetic Electron Precipitation Observed in Long-Term DEMETER Spacecraft Measurements

We analyze low-altitude DEMETER spacecraft measurements obtained between 2006 and 2010, complemented by WWLLN lightning location data, to investigate the importance of lightning-generated whistlers for the energetic electron precipitation from the Van Allen radiation belts. We focus, in particular, on the United States region, where a significant seasonal variation in the occurrence of lightning has been observed. We show that both the precipitating electron fluxes and very low frequency wave intensities correlate well with the total lightning occurrence in the region. We further demonstrate that lightning-induced electron precipitation is more significant during periods of low geomagnetic activity compared to periods of high geomagnetic activity and during the nighttime than during the daytime. The energies of precipitating energetic electrons extend up to about 700 keV, roughly in agreement with the cyclotron resonance theory. Precipitating electron fluxes are correlated with the total lightning occurrence in the region Lightning-induced electron precipitation is more pronounced during the nighttime and during periods of low geomagnetic activity The precipitated electron energies range up to a few hundred keV, roughly in agreement with the cyclotron resonance theory