Seasonal dependence of energetic electron precipitation: Evidence for a global role of lightning

Abstract

Analysis of the DEMETER spacecraft particle data shows that energetic electron precipitation exhibits a seasonal dependence consistent with lighting-induced electron precipitation (LEP). Over the United States, energetic electron fluxes in the slot region (between L = 2 and 3) are significantly higher in the northern summer than in the winter, consistent with the seasonal variation of lightning activity in the Northern Hemisphere. The association of precipitating fluxes with lightning is explored using lightning location data from the National Lightning Detection Network (NLDN) and VLF wave data on DEMETER. The increased precipitation of particles into the drift loss cone over the Northern Hemisphere in summer is consistent with expected pitch-angle scattering by lightning-generated whistler waves, indicating that lightning is a significant contributor to the loss of slot region electrons. Copyright 2009 by the American Geophysical Union.