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| Titel |
Sensitivity of a global model to the uptake of N2O5 by tropospheric aerosol |
| VerfasserIn |
H. L. Macintyre, M. J. Evans |
| 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. 15 ; Nr. 10, no. 15 (2010-08-09), S.7409-7414 |
| Datensatznummer |
250008694
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| Publikation (Nr.) |
 copernicus.org/acp-10-7409-2010.pdf |
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| Zusammenfassung |
The uptake of N2O5 on aerosol impacts atmospheric
concentrations of NOx and so O3, OH, and hence
CH4. Laboratory studies show significant variation in the rate
of uptake, with a general decline in the value of
γN2O5 over the last decade as increasingly relevant
tropospheric proxies have been studied. In order to understand the
implication of this decline for tropospheric composition, a global
model of tropospheric chemistry and transport (GEOS-Chem) is run with
differing values of γN2O5 (0.0, 10×10−6,
10×10−4, 10−3, 5×10−3, 10−2, 2×10×10−2,
0.1, 0.2, 0.5, and 1.0). We identify three regimes in the model
response. At low values of γN2O5, the model shows
reduced sensitivity to the value of γN2O5 as
heterogeneous uptake of γN2O5 does not provide a significant
pathway to perturb NOx burdens. At high values of
γN2O5 the model again shows reduced sensitivity to
the value of γN2O5, as NOx loss through
heterogeneous removal of γN2O5 is limited by the rate of
production of NO3, rather than the rate of heterogeneous
uptake. At intermediate values of γN2O5 the model
shows significant sensitivity to the value of
γN2O5. We find regional differences in the model's
response to changing γN2O5. Regions with high
aerosol surface area and low temperatures show NO3 production
becoming rate limiting at lower γN2O5 values than
regions with lower aerosol surface area and higher temperatures. The
northern extra-tropics show significant sensitivity to the value of
γN2O5 at values consistent with current literature
(0.001–0.02), thus an accurate description of
γN2O5 is required for adequate simulation of
O3 burdens and long-range transport of pollutants in this
region.
Our model simulations also provide insight into
the sensitivity of coupled chemistry-aerosol simulations to the choice
of γN2O5. We find little change in the
global sensitivity of NOx, O3 and OH
to γN2O5 in the range 0.05 to
1.0, but a significant drop in sensitivity below this range. Thus
simulations of the coupled impact of both chemistry and aerosol
changes through time will be sensitive to the choice of
γN2O5. |
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