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| Titel |
Potential impact of iodinated replacement compounds CF3I and CH3I on atmospheric ozone: a three-dimensional modeling study |
| VerfasserIn |
D. Youn, K. O. Patten, D. J. Wuebbles, H. Lee, C.-W. So |
| 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 ; 10, no. 20 ; Nr. 10, no. 20 (2010-10-29), S.10129-10144 |
| Datensatznummer |
250008858
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| Publikation (Nr.) |
 copernicus.org/acp-10-10129-2010.pdf |
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| Zusammenfassung |
| The concept of Ozone Depletion Potentials (ODPs) is extensively used in
policy considerations related to concerns about the effects of various
halocarbons and other gases on stratospheric ozone. Many of the recent
candidate replacement compounds have atmospheric lifetimes shorter than one
year in order to limit their environmental effects, especially on
stratospheric ozone. Using a three-dimensional global chemistry-transport
model (CTM) of the troposphere and the stratosphere, the purpose of this
study is to evaluate the potential effects of several very short-lived
iodinated substances, namely iodotrifluoromethane (CF3I) and methyl
iodide (CH3I), on atmospheric ozone. Like other chemicals with
extremely short lifetimes, the stratospheric halogen loading and resulting
ozone effects from these compounds are strongly dependent on the location of
emissions. For CF3I, a possible replacement candidate for
bromotrifluoromethane (CF3Br), ODPs derived by the three-dimensional
model are 0.008 with chemical lifetime of 5.03 days and 0.016 with a
lifetime of 1.13 days for emissions assumed to be evenly distributed over
land surfaces at mid-latitudes and the tropics, respectively. While this is
the first time the ODPs have been evaluated with a three-dimensional model,
these values are in good agreement with those derived previously. The model
calculations suggest that tropical convection could deliver a larger portion
of the gas and their breakdown products to the upper troposphere and lower
stratosphere if emission source is located in the tropics. The resulting ODP
for CH3I, emitted from mid-latitudes, is 0.017 with lifetime of 13.59
days. Valid simulations of convective transport, vertical mixing and
degradation chemistry of CH3I are shown that have good qualitative
agreement between the model derived distribution of background CH3I,
based on global source emission fluxes from previous studies, and available
observations especially in vertical profiles. |
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