Southern hemispheric halon trends and global halon emissions, 1978–2011

Newland, M. J., Reeves, C. E., Oram, D. E., Laube, J. C., Sturges, W. T., Hogan, C., Begley, P. and Fraser, P. J. (2013) Southern hemispheric halon trends and global halon emissions, 1978–2011. Atmospheric Chemistry and Physics, 13 (11). pp. 5551-5565.

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    Abstract

    The atmospheric records of four halons, H-1211 (CBrClF2), H-1301 (CBrF3), H-2402 (CBrF2CBrF2) and H-1202 (CBr2F2), measured from air collected at Cape Grim, Tasmania, between 1978 and 2011, are reported. Mixing ratios of H-1211, H-2402 and H-1202 began to decline in the early to mid-2000s, but those of H-1301 continue to increase up to mid-2011. These trends are compared to those reported by NOAA (National Oceanic and Atmospheric Administration) and AGAGE (Advanced Global Atmospheric Experiment). The observations suggest that the contribution of the halons to total tropospheric bromine at Cape Grim has begun to decline from a peak in 2008 of about 8.1 ppt. An extrapolation of halon mixing ratios to 2060, based on reported banks and predicted release factors, shows this decline becoming more rapid in the coming decades, with a contribution to total tropospheric bromine of about 3 ppt in 2060. Top-down global annual emissions of the halons were derived using a two-dimensional atmospheric model. The emissions of all four have decreased since peaking in the late 1980s–mid-1990s, but this decline has slowed recently, particularly for H-1301 and H-2402 which have shown no decrease in emissions over the past five years. The UEA (University of East Anglia) top-down model-derived emissions are compared to those reported using a top-down approach by NOAA and AGAGE and the bottom-up estimates of HTOC (Halons Technical Options Committee). The implications of an alternative set of steady-state atmospheric lifetimes are discussed. Using a lifetime of 14 yr or less for H-1211 to calculate top-down emissions estimates would lead to small, or even negative, estimated banks given reported production data. Finally emissions of H-1202, a product of over-bromination during the production process of H-1211, have continued despite reported production of H-1211 ceasing in 2010. This raises questions as to the source of these H-1202 emissions.

    Item Type: Article
    Additional Information: The modelling work in this paper has been funded through a PhD studentship (Newland) tied to the NERC project “A Century-long Record of Trace Gases in the Northern Hemisphere from the NEEM Ice Core Drilling Project in Greenland” (NE/F021194/1). The measurements were supported by the European Commission (Project No. 226224: SHIVA) and the UK’s Natural Environment Research Council (NERC), the latter through the National Centre for Atmospheric Science (NCAS, Oram) and an Advanced Research Fellowship (NE/I021918/1, Laube).
    Faculty \ School: Faculty of Science > School of Environmental Sciences
    Related URLs:
    Depositing User: Pure Connector
    Date Deposited: 04 Nov 2013 22:10
    Last Modified: 24 May 2019 11:30
    URI: https://ueaeprints.uea.ac.uk/id/eprint/44227
    DOI: 10.5194/acp-13-5551-2013

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