Hossaini, R. and Chipperfield, M. P. and Saiz-Lopez, A. and Harrison, J. J. and von Glasow, R. and Sommariva, R. and Atlas, E. and Navarro, M. and Montzka, S. A. and Feng, W. and Dhomse, S. and Harth, C. and Mühle, J. and Lunder, C. and O'Doherty, S. and Young, D. and Reimann, S. and Vollmer, M. K. and Krummel, P. B. and Bernath, P. F. (2015) Growth in stratospheric chlorine from short-lived chemicals not controlled by the Montreal Protocol. Geophysical Research Letters, 42 (11). pp. 4573-4580. ISSN 0094-8276
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Abstract
We have developed a chemical mechanism describing the tropospheric degradation of chlorine containing very short-lived substances (VSLS). The scheme was included in a global atmospheric model and used to quantify the stratospheric injection of chlorine from anthropogenic VSLS ( inline image) between 2005 and 2013. By constraining the model with surface measurements of chloroform (CHCl3), dichloromethane (CH2Cl2), tetrachloroethene (C2Cl4), trichloroethene (C2HCl3), and 1,2-dichloroethane (CH2ClCH2Cl), we infer a 2013 inline image mixing ratio of 123 parts per trillion (ppt). Stratospheric injection of source gases dominates this supply, accounting for ∼83% of the total. The remainder comes from VSLS-derived organic products, phosgene (COCl2, 7%) and formyl chloride (CHClO, 2%), and also hydrogen chloride (HCl, 8%). Stratospheric inline image increased by ∼52% between 2005 and 2013, with a mean growth rate of 3.7 ppt Cl/yr. This increase is due to recent and ongoing growth in anthropogenic CH2Cl2—the most abundant chlorinated VSLS not controlled by the Montreal Protocol.