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| Titel |
Aerosol chemical and optical properties over the Paris area within ESQUIF project |
| VerfasserIn |
A. Hodzic, R. Vautard, P. Chazette, L. Menut, B. Bessagnet |
| 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 ; 6, no. 11 ; Nr. 6, no. 11 (2006-08-08), S.3257-3280 |
| Datensatznummer |
250004052
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| Publikation (Nr.) |
 copernicus.org/acp-6-3257-2006.pdf |
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| Zusammenfassung |
| Aerosol chemical and optical properties are extensively investigated for the
first time over the Paris Basin in July 2000 within the ESQUIF project. The
measurement campaign offers an exceptional framework to evaluate the
performances of the chemistry-transport model CHIMERE in simulating
concentrations of gaseous and aerosol pollutants, as well as the
aerosol-size distribution and composition in polluted urban environments
against ground-based and airborne measurements. A detailed comparison of
measured and simulated variables during the second half of July with
particular focus on 19 and 31 pollution episodes reveals an overall good
agreement for gas-species and aerosol components both at the ground level
and along flight trajectories, and the absence of systematic biases in
simulated meteorological variables such as wind speed, relative humidity and
boundary layer height as computed by the MM5 model. A good consistency in
ozone and NO concentrations demonstrates the ability of the model to
reproduce the plume structure and location fairly well both on 19 and 31
July, despite an underestimation of the amplitude of ozone concentrations on
31 July. The spatial and vertical aerosol distributions are also examined by
comparing simulated and observed lidar vertical profiles along flight
trajectories on 31 July and confirm the model capacity to simulate the plume
characteristics. The comparison of observed and modeled aerosol components in
the southwest suburb of Paris during the second half of July indicates that
the aerosol composition is rather correctly reproduced, although the total
aerosol mass is underestimated by about 20%. The simulated Parisian
aerosol is dominated by primary particulate matter that accounts for
anthropogenic and biogenic primary particles (40%), and inorganic aerosol
fraction (40%) including nitrate (8%), sulfate (22%) and ammonium
(10%). The secondary organic aerosols (SOA) represent 12% of the total
aerosol mass, while the mineral dust accounts for 8%. The comparison
demonstrates the absence of systematic errors in the simulated sulfate,
ammonium and nitrates total concentrations. However, for nitrates the
observed partition between fine and coarse mode is not reproduced. In
CHIMERE there is a clear lack of coarse-mode nitrates. This calls for
additional parameterizations in order to account for the heterogeneous
formation of nitrate onto dust particles. Larger discrepancies are obtained
for the secondary organic aerosols due to both inconsistencies in the SOA
formation processes in the model leading to an underestimation of their mass
and large uncertainties in the determination of the measured aerosol organic
fraction. The observed mass distribution of aerosols is not well reproduced,
although no clear explanation can be given. |
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