Global and Seasonal Assessments of Atmosphere-Ionosphere-Magnetosphere Coupling via Lightning-Induced Electron Precipitation

Pitch-angle scattering by radio waves in the VLF ( 3-30kHz) band is thought to be a major loss mechanism for energetic radiation-belt electrons. Resonant interactions with Whistler-mode VLF waves can alter the reflection altitude of trapped electrons 100keV - 1MeV; when a particle reflects at a low enough altitude, it can be removed from the magnetosphere through collisions with ionospheric constituents. Terrestrial lightning provides a natural and constantly-occurring source of VLF waves. Here we present a global assessment of lightning-induced electron precipitation (LEP) due to resonant pitch-angle scattering from whistler-mode waves, which represent a coupling process between the atmosphere, ionosphere, and magnetosphere. Previous efforts have used two-dimensional raytracing combined with analytical expressions of pitch-angle scattering to forward model precipitation from a single stroke as a function of input and output latitude. We expand on this technique by incorporating three-dimensional raytracing through a realistic plasmasphere model, to better capture the longitude-dependence of precipitation. We then combine our end-to-end model of the LEP process with terrestrial lightning activity data from the GLD360 sensor network to construct a realtime geospatial model of LEP-driven energy deposition into the ionosphere. We explore global and seasonal statistics, provide precipitation estimates across a variety of magnetospheric conditions, and compare the total impact to other magnetospheric loss processes.