HR: 12:05h
AN: AE42A-08    [Abstracts]
TI: Plasma Chemistry of Sprite Streamers
AU: * Sentman, D
EM: dsentman@gi.alaska.edu
AF: University of Alaska, Geophysical Institute, Fairbanks, AK 99775, United States
AU: Stenbaek-Nielsen, H
EM: hnielsen@gi.alaska.edu
AF: University of Alaska, Geophysical Institute, Fairbanks, AK 99775, United States
AU: McHarg, M
EM: Matthew.Mcharg@usafa.af.mil
AF: U.S. Air Force Academy, 2354 Fairchild Dr., Colorado Springs, CO 80840,
AU: Morrill, J
EM: morrill@shogun.nrl.navy.mil
AF: Naval Research Laboratory, Solar Physics Branch, Washington, DC 20375,
AB: The expected chemical effects of passage of a sprite streamer through the mesosphere at an altitude of 70 km are described using a nonlinear coupled chemistry model of 80+ species and 500+ reactions. The transient ionization and chemical response of the atmosphere are computed for a streamer descending at high speed ~10⁷ m s^-1. The streamer head impulsively (τ~10 μs) ionizes the gas (fractional ionization density ~10^-9) and creates large populations of dissociated and excited neutral byproducts. Electrons created by ionization within the head persist for about 1 s, with losses occurring approximately equally by dissociative attachment with ambient O₃, and by dissociative recombination with the positive ion dimer N₂O₂⁺ created in the sprite channel by a two-step process involving O₂⁺ creation via N₂⁺ charge exchange. Large amounts (fractional densities ~10^-9) of metastables are created, with most of them persisting for less than 1 second. These include a possibly detectable (~1 kR) enhancement of O₂ Atmospheric airglow emissions from metastable O₂(b¹Σ_g⁺) populations. Electron impact- dissociated N(²D) interacts with O₂ to create a long lived (>100 s) increase (fractional enhancement >50%) of the ambient NO density within the streamer channel. Other long lived (>100 s) effects are weak O₂ Infrared Atmospheric emissions from metastable O₂(a¹Δ_g), and OH Meinel emissions produced by O(³P) perturbations to the catalytic cycle of hydroxyl chemistry.
DE: 0310 Airglow and aurora
DE: 0317 Chemical kinetic and photochemical properties
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
SC: Atmospheric and Space Electricity [AE]
MN: 2007 Fall Meeting