Cumulative Effects of Lightning Electromagnetic Pulses on the Lower Ionosphere

Lightning strokes emit electromagnetic pulses that interact with the lower ionosphere. One manifestation of this interaction are elves: Ring-shaped light emissions from altitudes around 85 km above ground produced by active thunderstorms. Perturbations to the conductivity at those altitudes relax with time-scales longer than 10 min and therefore one strong pulse may affect the features of subsequent pulses. Here we develop a simplified model to investigate this possibility. We apply this model to thunderstorms with a copious production of high-peak-current strokes, finding changes in the altitude profile of light emissions for elves at different stages of the thunderstorm evolution.