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UP: Umweltphysik

UP 15: Poster: Atmosph
äre und Klima

UP 15.1: Poster

Tuesday, March 14, 2006, 14:00–16:00, C

Ozone Depletion Events, in the Polar Boundary Layer in Spring: A Model Study — •Matthias Piot and Roland von Glasow — Institut fuer Umweltphysik 69120 Heidelberg

Reactive halogens play a major role in ozone depletion events (ODE). The reaction of bromine atoms with ozone, followed by the self-reaction of bromine oxides (BrO) represents a catalytic loss mechanism for ozone in the polar boundary layer (PBL). However, the triggering of the so-called No-dqbromine explosionNo-dq remains unclear. We used the chemical and microphysical model MISTRA to study the mechanisms leading to these observed depletions in the boundary layer. We will present model results where we used prescribed bromine or chlorine fluxes as responsible for ODEs. Our sensitivity study consisted in a set of four-day runs where we changed initial mixing ratios or fluxes (or both) of 19 different species (including halogens, NOx, NOy, DMS, H2O2, HCHO... ) and compared the results with base runs. Temperature and humidity has also been examined. We investigated the importance of these compounds for the chemistry of the PBL and focused on species which influence the occurrence of an ODE. In addition to the sensitivity study, we are now examining the role that frost flowers play in the bromine explosion, using MISTRA in the lagrangian 1D mode. The considered column passes over a field of frost flowers, followed by an area of open lead. We observed that all the bromide from sea salt aerosols is released to the gas phase. Our results indicate that aerosols from frost flowers are probably not directly responsible for the bromine explosion and that additional cycles have to been taken into account.