Atmos. Chem. Phys. Discuss., 13, 20463-20502, 2013
© Author(s) 2013. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Estimates of tropical bromoform emissions using an inversion method
M. J. Ashfold1, N. R. P. Harris1, A. J. Manning2, A. D. Robinson1, N. J. Warwick1,3, and J. A. Pyle1,3
1Department of Chemistry, University of Cambridge, Cambridge, UK
2Met Office, Exeter, UK
3National Centre for Atmospheric Science, UK

Abstract. Bromine plays an important role in ozone chemistry in both the troposphere and stratosphere. When measured by mass, bromoform (CHBr3) is thought to be the largest organic source of bromine to the atmosphere. While seaweed and phytoplankton are known to be dominant sources, the size and the geographical distribution of CHBr3 emissions remains uncertain. Particularly little is known about emissions from the Maritime Continent, which have usually been assumed to be large, and which appear to be especially likely to reach the stratosphere. In this study we aim to use the first multi-annual set of CHBr3 measurements from this region, and an inversion method, to reduce this uncertainty. We find that local measurements of a short-lived gas like CHBr3 can only be used to constrain emissions from a relatively small, sub-regional domain. We then obtain detailed estimates of both the distribution and magnitude of CHBr3 emissions within this area. Our estimates appear to be relatively insensitive to the assumptions inherent in the inversion process. We extrapolate this information to produce estimated emissions for the entire tropics (defined as 20° S–20° N) of 225 GgCHBr3 y-1. This estimate is consistent with other recent studies, and suggests that CHBr3 emissions in the coastline-rich Maritime Continent may not be stronger than emissions in other parts of the tropics.

Citation: Ashfold, M. J., Harris, N. R. P., Manning, A. J., Robinson, A. D., Warwick, N. J., and Pyle, J. A.: Estimates of tropical bromoform emissions using an inversion method, Atmos. Chem. Phys. Discuss., 13, 20463-20502, doi:10.5194/acpd-13-20463-2013, 2013.
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