Impact of reactive bromine chemistry in the troposphere

R. von Glasow (1, 2) , R. von Kuhlmann (3) , M. G. Lawrence (3) , U. Platt (2) , P. J. Crutzen (2, 3)

1 IUP - Institute of Environmental Physics [Heidelberg]
2 Center for Atmospheric Sciences [La Jolla]
3 Atmospheric Chemistry Department [MPIC]

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 NO_x 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.

Domaines: Océan, Atmosphère

R. von Glasow, R. von Kuhlmann, M. G. Lawrence, U. Platt, P. J. Crutzen. Impact of reactive bromine chemistry in the troposphere. Atmospheric Chemistry and Physics Discussions, 2004, 4 (4), pp.4877-4913. ⟨hal-00301407⟩