ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-4-2481-2004 Impact of reactive bromine chemistry in the troposphere von Glasow R. 2 1 von Kuhlmann R. 3 4 Lawrence M. G. 3 Platt U. 2 Crutzen P. J. 3 2 Institute for Environmental Physics, Universität Heidelberg, Germany Center for Atmospheric Sciences, Scripps Institution of Oceanography, University of California, San Diego, USA Atmospheric Chemistry Division, Max-Planck-Institut für Chemie, Mainz, Germany now at: German Aerospace Center (DLR), Bonn-Oberkassel, Germany 08 12 2004 4 11/12 2481 2497 Copyright: © 2004 R. von Glasow et al. 2004 This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/ This article is available from https://acp.copernicus.org/articles/4/2481/2004/acp-4-2481-2004.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/4/2481/2004/acp-4-2481-2004.pdf

Recently several field campaigns and satellite observations have found strong indications for the presence of bromine oxide (BrO) in the free troposphere. Using a global atmospheric chemistry transport model we show that BrO mixing ratios of a few tenths to 2 pmol mol<sup>-1</sup> lead to a reduction in the zonal mean O<sub>3</sub> 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. In addition there are changes in the HO<sub>2</sub>:OH ratio that also affect NO<sub>x</sub> and PAN. These results imply that potentially significant strong sinks for O<sub>3</sub> and DMS have so far been ignored in many studies of the chemistry of the troposphere.