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| Titel |
Southern hemispheric halon trends and global halon emissions, 1978–2011 |
| VerfasserIn |
M. J. Newland, C. E. Reeves, D. E. Oram, J. C. Laube, W. T. Sturges, C. Hogan, P. Begley, P. J. Fraser |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 11 ; Nr. 13, no. 11 (2013-06-06), S.5551-5565 |
| Datensatznummer |
250018688
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| Publikation (Nr.) |
 copernicus.org/acp-13-5551-2013.pdf |
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| Zusammenfassung |
| 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. |
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