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| Titel |
Explicit calculation of indirect global warming potentials for halons using atmospheric models |
| VerfasserIn |
D. Youn, K. O. Patten, J.-T. Lin, D. J. Wuebbles |
| 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 ; 9, no. 22 ; Nr. 9, no. 22 (2009-11-16), S.8719-8733 |
| Datensatznummer |
250007753
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| Publikation (Nr.) |
 copernicus.org/acp-9-8719-2009.pdf |
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| Zusammenfassung |
| The concept of Global Warming Potentials (GWPs) has been extensively used in
policy consideration as a relative index for comparing the climate impact of
an emitted greenhouse gas (GHG), relative to carbon dioxide with equal mass
emissions. Ozone depletion due to emission of chlorinated or brominated
halocarbons leads to cooling of the climate system in the opposite direction
to the direct warming contribution by halocarbons as GHGs. This cooling is a
key indirect effect of the halocarbons on climatic radiative forcing, which
is accounted for by indirect GWPs. With respect to climate, it is critical
to understand net influences considering direct warming and indirect cooling
effects especially for Halons due to the greater ozone-depleting efficiency
of bromine over chlorine. Until now, the indirect GWPs have been calculated
using a parameterized approach based on the concept of Equivalent Effective
Stratospheric Chlorine (EESC) and the observed ozone depletion over the last
few decades. As a step towards obtaining indirect GWPs through a more robust
approach, we use atmospheric models to explicitly calculate the indirect
GWPs of Halon-1211 and Halon-1301 for a 100-year time horizon.
State-of-the-art global chemistry-transport models (CTMs) were used as the
computational tools to derive more realistic ozone depletion changes caused
by an added pulse emission of the two major Halons at the surface. The
radiative forcings on climate from the ozone changes have been calculated
for indirect GWPs using an atmospheric radiative transfer model (RTM). The
simulated temporal variations of global average total column Halons after a
pulse perturbation follow an exponential decay with an e-folding time which
is consistent with the expected chemical lifetimes of the Halons. Our
calculated indirect GWPs for the two Halons are much smaller than those from
past studies but are within a single standard deviation of WMO (2007) values
and the direct GWP values derived agree with the published values. Our
model-based assessment of the Halon indirect GWPs thus confirms the
significant importance of indirect effects on climate. |
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