1Institute for Climate and Atmospheric Science (ICAS), School of Earth and Environment, University of Leeds, Leeds, UK
2National Oceanic and Atmospheric Administration, Boulder, USA
4GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
5Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, USA
6Institute for Atmospheric and Environmental Sciences, Universität Frankfurt/Main, Germany
7School of Environmental Sciences, University of East Anglia, Norwich, UK
8Met Office, Exeter, UK
9Atmospheric Chemistry and Climate Group, Institute for Physical Chemistry Rocasolano, CSIC, Madrid, Spain
10National Centre for Atmospheric Science (NCAS), University of Cambridge, Cambridge, UK
11Universities Space Research Association, GESTAR, Columbia, Maryland, USA
12Institute for Environmental Physics, University of Heidelberg, Heidelberg, Germany
*now at: Department of Geosciences, University of Oslo, Oslo, Norway
Received: 09 Apr 2013 – Discussion started: 14 May 2013
Abstract. Emissions of halogenated very short-lived substances (VSLS) are poorly constrained. However, their inclusion in global models is required to simulate a realistic inorganic bromine (Bry) loading in both the troposphere, where bromine chemistry perturbs global oxidising capacity, and in the stratosphere, where it is a major sink for ozone (O3). We have performed simulations using a 3-D chemical transport model (CTM) including three top-down and a single bottom-up derived emission inventory of the major brominated VSLS bromoform (CHBr3) and dibromomethane (CH2Br2). We perform the first concerted evaluation of these inventories, comparing both the magnitude and spatial distribution of emissions. For a quantitative evaluation of each inventory, model output is compared with independent long-term observations at National Oceanic and Atmospheric Administration (NOAA) ground-based stations and with aircraft observations made during the NSF (National Science Foundation) HIAPER Pole-to-Pole Observations (HIPPO) project. For CHBr3, the mean absolute deviation between model and surface observation ranges from 0.22 (38%) to 0.78 (115%) parts per trillion (ppt) in the tropics, depending on emission inventory. For CH2Br2, the range is 0.17 (24%) to 1.25 (167%) ppt. We also use aircraft observations made during the 2011 Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere (SHIVA) campaign, in the tropical western Pacific. Here, the performance of the various inventories also varies significantly, but overall the CTM is able to reproduce observed CHBr3 well in the free troposphere using an inventory based on observed sea-to-air fluxes. Finally, we identify the range of uncertainty associated with these VSLS emission inventories on stratospheric bromine loading due to VSLS (BryVSLS). Our simulations show BryVSLS ranges from ~4.0 to 8.0 ppt depending on the inventory. We report an optimised estimate at the lower end of this range (~4 ppt) based on combining the CHBr3 and CH2Br2 inventories which give best agreement with the compilation of observations in the tropics.
Revised: 18 Sep 2013 – Accepted: 04 Nov 2013 – Published: 06 Dec 2013
Hossaini, R., Mantle, H., Chipperfield, M. P., Montzka, S. A., Hamer, P., Ziska, F., Quack, B., Krüger, K., Tegtmeier, S., Atlas, E., Sala, S., Engel, A., Bönisch, H., Keber, T., Oram, D., Mills, G., Ordóñez, C., Saiz-Lopez, A., Warwick, N., Liang, Q., Feng, W., Moore, F., Miller, B. R., Marécal, V., Richards, N. A. D., Dorf, M., and Pfeilsticker, K.: Evaluating global emission inventories of biogenic bromocarbons, Atmos. Chem. Phys., 13, 11819-11838, doi:10.5194/acp-13-11819-2013, 2013.