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| Titel |
Megacity emission plume characteristics in summer and winter investigated by mobile aerosol and trace gas measurements: the Paris metropolitan area |
| VerfasserIn |
S.-L. Weiden-Reinmüller, F. Drewnick, Q. J. Zhang, F. Freutel, M. Beekmann, S. Borrmann |
| 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 ; 14, no. 23 ; Nr. 14, no. 23 (2014-12-08), S.12931-12950 |
| Datensatznummer |
250119217
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| Publikation (Nr.) |
 copernicus.org/acp-14-12931-2014.pdf |
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| Zusammenfassung |
| For the investigation of megacity emission plume characteristics mobile
aerosol and trace gas measurements were carried out in the greater Paris
region in July 2009 and January–February 2010 within the EU FP7 MEGAPOLI
project (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate
effects, and Integrated tools for assessment and mitigation). The deployed instruments measured physical and chemical properties
of sub-micron aerosol particles, gas phase constituents of relevance for
urban air pollution studies and meteorological parameters. The emission
plume was identified based on fresh pollutant (e.g., particle-bound
polycyclic aromatic hydrocarbons, black carbon, CO2 and NOx)
concentration changes in combination with wind direction data. The
classification into megacity influenced and background air masses allowed a
characterization of the emission plume during summer and winter
environmental conditions. On average, a clear increase of fresh pollutant
concentrations in plume compared to background air masses was found for both
seasons. For example, an average increase of 190% (+ 8.8 ng m−3)
in summer and of 130% (+ 18.1 ng m−3) in winter was found for
particle-bound polycyclic aromatic hydrocarbons in plume air masses. The
aerosol particle size distribution in plume air masses was influenced by
nucleation and growth due to coagulation and condensation in summer, while
in winter only the latter process (i.e., particle growth) seemed to be
initiated by urban pollution. The observed distribution of fresh pollutants
in the emission plume – its cross sectional Gaussian-like profile and the
exponential decrease of pollutant concentrations with increasing distance to
the megacity – are in agreement with model results. Differences between
model and measurements were found for plume center location, plume width and
axial plume extent. In general, dilution was identified as the dominant
process determining the axial variations within the Paris emission plume.
For in-depth analysis of transformation processes occurring in the advected
plume, simultaneous measurements at a suburban measurement site and a
stationary site outside the metropolitan area using the mobile laboratory
have proven to be most useful. Organic aerosol oxidation was observed in
summer, while in winter transformation processes seemed to occur at a slower
rate. |
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