Author:
Hossaini R.,Chipperfield M. P.,Feng W.,Breider T. J.,Atlas E.,Montzka S. A.,Miller B. R.,Moore F.,Elkins J.
Abstract
Abstract. We have used a global three-dimensional chemical transport model to quantify the impact of the very short-lived substances (VSLS) CHBr3, CH2Br2, CHBr2Cl, CHBrCl2, CH2BrCl and C2H5-Br on the bromine budget of the stratosphere. Atmospheric observations of these gases allow constraints on surface mixing ratios that, when incorporated into our model, contribute ~4.9–5.2 parts per trillion (ppt) of inorganic bromine (Bry) to the stratosphere. Of this total, ~76 % comes from naturally-emitted CHBr3 and CH2Br2. The remaining species individually contribute modest amounts. However, their accumulated total accounts for up to ~1.2 ppt of the supply and thus should not be ignored. We have compared modelled tropical profiles of a range of VSLS with observations from the recent 2009 NSF HIPPO-1 aircraft campaign. Modelled profiles agree reasonably well with observations from the surface to the lower tropical tropopause layer. We have also considered the poorly studied anthropogenic VSLS, C2H5Br, CH2BrCH2Br, n-C3H7Br and i-C3H7Br. We find the local atmospheric lifetime of these species in the tropical tropopause layer are ~183, 603, 39 and 49 days, respectively. These species, particularly C2H5Br and CH2BrCH2Br, would thus be important carriers of bromine to the stratosphere if emissions were to increase substantially. Our model shows ~70–73 % and ~80–85 % of bromine from these species in the tropical boundary layer can reach the lower stratosphere.
Cited by
58 articles.
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