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| Titel |
Evolution of Asian aerosols during transpacific transport in INTEX-B |
| VerfasserIn |
E. J. Dunlea, P. F. DeCarlo, A. C. Aiken, J. R. Kimmel, R. E. Peltier, R. J. Weber, J. Tomlinson, D. R. Collins, Y. Shinozuka, C. S. McNaughton, S. G. Howell, A. D. Clarke, L. K. Emmons, E. C. Apel, G. G. Pfister, A. Donkelaar, R. V. Martin, D. B. Millet, C. L. Heald, J. L. Jimenez |
| 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 ; 9, no. 19 ; Nr. 9, no. 19 (2009-10-01), S.7257-7287 |
| Datensatznummer |
250007659
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| Publikation (Nr.) |
 copernicus.org/acp-9-7257-2009.pdf |
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| Zusammenfassung |
| Measurements of aerosol composition were made with an Aerodyne High
Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) on board
the NSF/NCAR C-130 aircraft as part of the Intercontinental Chemical
Transport Experiment Phase B (INTEX-B) field campaign over the Eastern
Pacific Ocean. The HR-ToF-AMS measurements of non-refractory submicron
aerosol mass are shown to compare well with other aerosol instrumentation in
the INTEX-B field study. Two case studies are described for pollution layers
transported across the Pacific from the Asian continent, intercepted 3–4
days and 7–10 days downwind of Asia, respectively. Aerosol chemistry is
shown to be a robust tracer for air masses originating in Asia, specifically
the presence of sulfate dominated aerosol is a distinguishing feature of
Asian pollution layers that have been transported to the Eastern Pacific. We
examine the time scales of processing for sulfate and organic aerosol in the
atmosphere and show that our observations confirm a conceptual model for
transpacific transport from Asia proposed by Brock et al. (2004). Our
observations of both sulfate and organic aerosol in aged Asian pollution
layers are consistent with fast formation near the Asian continent, followed
by washout during lofting and subsequent transformation during transport
across the Pacific. Our observations are the first atmospheric measurements
to indicate that although secondary organic aerosol (SOA) formation from
pollution happens on the timescale of one day, the oxidation of organic
aerosol continues at longer timescales in the atmosphere. Comparisons with
chemical transport models of data from the entire campaign reveal an
under-prediction of organic aerosol mass in the MOZART model, but much
smaller discrepancies with the GEOS-Chem model than found in previous
studies over the Western Pacific. No evidence is found to support a previous
hypothesis for significant secondary organic aerosol formation in the free
troposphere. |
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