Simulations and Theory of Streamer Discharges in Transient Luminous Events

Transient luminous events (TLEs) are large-scale optical events occurring in Earth's stratosphere, mesosphere and lower thermosphere that are directly related to electrical activity in underlying thunderstorms. TLEs impulsively couple the troposphere to the ionosphere and may result in heating, acceleration, and photoionization in the lower thermosphere. TLEs are richly structured phenomena, whose fundamental elements are filamentary plasmas called streamers. TLE studies are critical for understanding the microphysics of streamer discharges, and also represent an important area in the research of the chemistry in the Earth's atmosphere. Field observations of streamers currently outpace theoretical developments, and consequently many aspects of streamer initiation are not well understood. The proposed work consists of theoretical investigations that will close several knowledge gaps. This proposal will also contribute to the education and training of undergraduate and graduate students.

The proposers will build upon an existing model by embedding small-scale phenomena (sprite streamer initiation) within a larger domain, and adding additional chemistry. Specifically the PI will investigate: 1. the role of plasma inhomogeneities in sprite streamer initiation; 2. propagation of streamers over long distances (~10 km) within stratified air density; and 3. the effects of sprites on lower ionospheric chemistry. These studies will inform industrial applications of streamers (including ozone production and pollution control) and TLE-related ionospheric modification.