Heidelberg 2015 – wissenschaftliches Programm
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UP: Fachverband Umweltphysik
UP 2: Atmosphäre
UP 2.13: Vortrag
Mittwoch, 25. März 2015, 13:45–14:00, G/gHS
A model study of the plasma chemistry of stratospheric Blue Jets — •Holger Winkler and Justus Notholt — Institut für Umweltphysik, Universität Bremen
Stratospheric Blue Jets (BJs) are upward propagating discharges in the altitude range 15–40 km above thunderstorms. They appear as conical bodies of blue light originating at the top of thunderclouds and proceed upward with velocities of the order of 100 km/s. BJs consist of an upward propagating leader which emits a fan of streamers.
Electric discharges in the atmosphere are known to have chemical effects. Reactive nitrogen and oxygen species are produced which initiate rapid ion-neutral reactions. Of particular interest from the atmospheric chemistry point of view is the formation of ozone, and the production of ozone depleting nitrogen radicals.
We have used a numerical plasma chemistry model in order to simulate the chemical processes in stratospheric BJs. It was applied to BJ streamers in the altitude range 18-38 km. Additionally, the chemical processes in the leader part of a BJ have been simulated for the first time. The model results indicate that there is considerable impact on nitrogen species and ozone. The chemical effects of the streamers predicted by our model are by orders of magnitude larger than in previous model studies. In the leader channel, driven by high-temperature reactions, the concentration of N2O and NO increases by several orders of magnitude, and there is a significant depletion of ozone.