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| Titel |
Modelling the ion chemistry of daytime sprite streamers |
| VerfasserIn |
Holger Winkler, Justus Notholt |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250079414
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| Zusammenfassung |
| Mesospheric electric breakdown events (sprites) are mainly nighttime phenomena. Therefore,
the ion chemical impacts of sprites have commonly been studied for nighttime conditions.
However, some daytime sprites have been detected. We present detailed model studies on the
chemical impacts of daytime sprite streamers. For this purpose, a plasma chemistry model
has been developed. It accounts for more than 90 species being relevant for the reactions in
sprite streamers, and several hundreds of reactions. The effects of solar photons
are considered by photolysis and photoelectron detachment processes. The model
simulations indicate that the chemical impacts of daytime sprites differ in some
respects from nighttime events. Due to photo-detachment of electrons from negative
ions, the density of seed electrons during the daytime is significantly larger than at
night. As a result, ionisation, dissociation and excitation rates are higher, and larger
amounts of reactive radicals are produced. The effect of electron photo-detachment
becomes important for the sprite ion chemistry after a few hundred milliseconds.
Furthermore, the changing atmospheric background chemistry between night and
day influence the longer-term effects, in particular in terms of nitrogen radicals. |
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