HR: 16:00h
AN: A14A-01 INVITED     [Abstracts]
TI: Modeling halogen chemistry: A first global assessment of the impact on the troposphere and processes in volcanic plumes
AU: * von Glasow, R
EM: Roland.von.Glasow@iup.uni-heidelberg.de
AF: Institute for Environmental Physics, University of Heidelberg, Im Neuenheimer Feld 229, Heidelberg, 69120 Germany
AB: An increasing number of measurements indicate the presence of a few tenths to 2 pmol~mol^-1 of bromine oxide in the free troposphere. Using a three-dimensional chemistry transport model we made a first global assessment of the potential effects of reactive bromine chemistry on the troposphere. We found a reduction in the zonal mean O₃ mixing ratio of up to 18% in widespread areas and regionally up to 40% compared to a model run without bromine chemistry. A lower limit approach for the marine boundary layer that does not explicitly include the release of halogens from sea salt aerosol, shows that for dimethyl sulfide (DMS) the effect is even larger, with up to 60% reduction of its tropospheric column. This is accompanied by dramatic changes in DMS oxidation pathways, reducing its cooling effect on climate. These results imply that potentially significant strong sinks for O₃ and DMS have so far been ignored in many studies of the chemistry of the troposphere. Bromine oxide has been measured in the plumes of several slowly erupting volcanoes. We will showpresent results from a one-dimensional model that includes a parameterization for the horizontal entrainment of background air as well as a detailed set of gas-phase and aerosol-phase reactions. We will show a comparison with data and discuss the results and possible implications of this for the chemistry of the troposphere.
DE: 0365 Troposphere: composition and chemistry
DE: 0370 Volcanic effects (8409)
DE: 0545 Modeling (4255)
DE: 8409 Atmospheric effects (0370)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005