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| Titel |
Characterizing the impact of urban emissions on regional aerosol particles: airborne measurements during the MEGAPOLI experiment |
| VerfasserIn |
E. J. Freney, K. Sellegri, F. Canonaco, A. Colomb, A. Borbon, V. Michoud, J.-F. Doussin, S. Crumeyrolle, N. Amarouche, J.-M. Pichon, T. Bourianne, L. Gomes, A. S. H. Prévôt, M. Beekmann, A. Schwarzenboeck |
| 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. 3 ; Nr. 14, no. 3 (2014-02-06), S.1397-1412 |
| Datensatznummer |
250118359
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| Publikation (Nr.) |
 copernicus.org/acp-14-1397-2014.pdf |
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| Zusammenfassung |
| The MEGAPOLI (Megacities: Emissions, urban, regional and Global
Atmospheric POLlution and climate effects, and Integrated tools for
assessment and mitigation) experiment took place in July 2009. The aim of this campaign
was to study the aging and reactions of aerosol and gas-phase emissions in
the city of Paris. Three ground-based measurement sites and several mobile
platforms including instrument equipped vehicles and the ATR-42 aircraft
were involved. We present here the variations in particle- and gas-phase
species over the city of Paris, using a combination of high-time resolution
measurements aboard the ATR-42 aircraft. Particle chemical composition was
measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS), giving detailed information on the non-refractory submicron
aerosol species. The mass concentration of black carbon (BC), measured by a
particle absorption soot photometer (PSAP), was used as a marker to identify
the urban pollution plume boundaries. Aerosol mass concentrations and
composition were affected by air-mass history, with air masses that spent
longest time over land having highest fractions of organic aerosol and
higher total mass concentrations. The Paris plume is mainly composed of
organic aerosol (OA), BC, and nitrate aerosol, as well as high
concentrations of anthropogenic gas-phase species such as toluene, benzene,
and NOx. Using BC and CO as tracers for air-mass dilution, we observe
the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase
with increasing photochemical age (−log(NOx / NOy)). Plotting the
equivalent ratios of different organic aerosol species (LV-OOA, SV-OOA, and
HOA) illustrate that the increase in OA is a result of secondary organic
aerosol (SOA) formation. Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in London, Mexico
City, and in New England, USA. Using the measured SOA volatile organic compounds (VOCs) species together
with organic aerosol formation yields, we were able to predict ~50% of
the measured organics. These airborne measurements during the MEGAPOLI
experiment show that urban emissions contribute to the formation of OA and
have an impact on aerosol composition on a regional scale. |
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