Impact of reactive bromine chemistry in the troposphere
1Institute for Environmental Physics, Universität Heidelberg, Germany
2Center for Atmospheric Sciences, Scripps Institution of Oceanography, University of California, San Diego, USA
3Atmospheric Chemistry Division, Max-Planck-Institut für Chemie, Mainz, Germany
Abstract. Recently several field campaigns and satellite observations found strong indications for bromine oxide (BrO) in the free troposphere. Using a global atmospheric chemistry transport model we show that BrO measurements mixing ratios of a few tenths to 2 pmol mol−1 lead to a reduction in the zonal mean O3 mixing ratio of up to 18% in widespread areas and locally even up to 40% compared to a model run without bromine chemistry. For dimethyl sulfide (DMS) the effect is even larger with up to 60% decreases. This is accompanied by dramatic changes in DMS oxidation pathways, reducing its cooling effect on climate. Changes in the HO2:OH ratio also cause changes for NOx and PAN. These results imply that a very strong sink for O3 and DMS has so far been ignored in many studies of the chemistry of the troposphere.