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| Titel |
Impact of model resolution on chemical ozone formation in Mexico City: application of the WRF-Chem model |
| VerfasserIn |
X. Tie, G. Brasseur, Z. Ying |
| 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. 18 ; Nr. 10, no. 18 (2010-09-28), S.8983-8995 |
| Datensatznummer |
250008791
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| Publikation (Nr.) |
 copernicus.org/acp-10-8983-2010.pdf |
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| Zusammenfassung |
| The resolution of regional chemical/dynamical models has important effects
on the calculation of the distributions of air pollutants in urban areas. In
this study, the sensitivity of air pollutants and photochemical ozone
production to different model resolutions is assessed by applying a regional
chemical/dynamical model (version 3 of Weather Research and Forecasting
Chemical model – WRF-Chemv3) to the case of Mexico City. The model results
with 3, 6, 12, and 24 km resolutions are compared to local surface
measurements of CO, NOx, and O3. The study shows that the model
resolutions of 3 and 6 km provide reasonable simulations of surface CO, NOx,
and O3 concentrations and of diurnal variations. The model tends to
underestimate the measurements when the resolution is reduced to 12 km or
less. The calculated surface CO, NOx, and O3 concentrations at 24 km
resolution are significantly lower than measured values. This study suggests
that the ratio of the city size to the threshold resolution is 6 to 1, and
that this ratio can be considered as a test value in other urban areas for
model resolution setting. There are three major factors related to the
effects of model resolution on the calculations of O3 and O3
precursors, including; (1) the calculated meteorological conditions, (2) the
spatial distribution for the emissions of ozone precursors, and (3) the
non-linearity in the photochemical ozone production. Model studies suggest
that, for the calculations of O3 and O3 precursors, spatial
resolutions (resulting from different meteorological condition and transport
processes) have larger impacts than the effect of the resolution associated
with emission inventories. The model shows that, with coarse resolution of
emission inventory (24 km) and high resolution for meteorological conditions
(6 km), the calculated CO and O3 are considerably improved compared to
the results obtained with coarse resolution for both emission inventory and
meteorological conditions (24 km). The resolution of the surface emissions
has important effects on the calculated concentration fields, but the
effects are smaller than those resulting from the model resolution. This
study also suggests that the effect of model resolution on O3
precursors leads to important impacts on the photochemical formation of
ozone. This results directly from the non-linear relationship between
O3 formation and O3 precursor concentrations. Finally, this study
suggests that, considering the balance between model performance and
required computation time on current computers, the 6 km resolution is an
optimal resolution for the calculation of ozone and its precursors in urban
areas like Mexico City. |
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