Chemical Activity of Low Altitude (50 km) Sprite Streamers

Abstract

AbstractA three‐stage simulation is used to explore the chemical influence of low altitude (50 km) sprite streamers on the atmosphere, including the chemical trail after the streamer has faded away. In the first stage (streamer phase) a 2D electrodynamical streamer model quantifies the generation of NOx and N2O, and the removal of ozone (O3) by a downward propagating streamer during Δtstreamer = 80 μs. This streamer propagation leads to a distinctive region in the streamer channel, the glow, where the electric field is enhanced. In the second stage (glow phase), the computed densities of the first stage are used as initial conditions for a 0D model to study the chemical evolution of the streamer channel, where we assume a remanent field of 100 Td for the glow and 0 Td elsewhere. This stage lasts Δtglow = 85 μs, the typical glow lifetime at 50 km. Finally, in the third stage (post‐streamer phase), we use the same 0D model, switch off the field in the glow region and let the whole streamer wake evolve roughly 100 s (100 s − Δtglow). Results show a key species such as O3 is mainly depleted during the streamer phase while NOx and N2O are predominantly produced during the same phase. We also compute the local increase of NO2 by sprite streamers at ∼50 km and find out that it could account for the measurable NO2 anomaly over thunderstorms reported from satellite‐based measurements.