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| Titel |
Identifying the causes of differences in ozone production from the CB05 and CBMIV chemical mechanisms |
| VerfasserIn |
R. D. Saylor, A. F. Stein |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 5, no. 1 ; Nr. 5, no. 1 (2012-02-21), S.257-268 |
| Datensatznummer |
250002304
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| Publikation (Nr.) |
 copernicus.org/gmd-5-257-2012.pdf |
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| Zusammenfassung |
| An investigation was conducted to identify the mechanistic differences
between two versions of the carbon bond gas-phase chemical mechanism (CB05
and CBMIV) which consistently lead to larger ground-level ozone
concentrations being produced in the CB05 version of the National Air
Quality Forecasting Capability (NAQFC) modeling system even though the two
parallel forecast systems utilize the same meteorology and base emissions
and similar initial and boundary conditions. Box models of each of the
mechanisms as they are implemented in the NAQFC were created and a set of 12
sensitivity simulations was designed. The sensitivity simulations
independently probed the conceptual mechanistic differences between CB05 and
CBMIV and were exercised over a 45-scenario simulation suite designed to
emulate the wide range of chemical regimes encountered in a
continental-scale atmospheric chemistry model. Results of the sensitivity
simulations indicate that two sets of reactions that were included in the
CB05 mechanism, but which were absent from the CBMIV mechanism, are the
primary causes of the greater ozone production in the CB05 version of the
NAQFC. One set of reactions recycles the higher organic peroxide species of
CB05 (ROOH), resulting in additional photochemically reactive products that
act to produce additional ozone in some chemical regimes. The other set of
reactions recycles reactive nitrogen from less reactive forms back to
NO2, increasing the effective NOx concentration of the system. In
particular, the organic nitrate species (NTR), which was a terminal product
for reactive nitrogen in the CBMIV mechanism, acts as a reservoir species in
CB05 to redistribute NOx from major source areas to potentially
NOx-sensitive areas where additional ozone may be produced in areas
remote from direct NOx sources. |
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