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Titel |
Dust specific extinction cross-sections over the Eastern Mediterranean using the BSC-DREAM model and sun photometer data: the case of urban environments |
VerfasserIn |
E. Gerasopoulos, P. Kokkalis, V. Amiridis, E. Liakakou, C. Pérez, K. Haustein, K. Eleftheratos, M. O. Andreae, T. W. Andreae, C. S. Zerefos |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
0992-7689
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Digitales Dokument |
URL |
Erschienen |
In: Annales Geophysicae ; 27, no. 7 ; Nr. 27, no. 7 (2009-07-22), S.2903-2912 |
Datensatznummer |
250016599
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Publikation (Nr.) |
copernicus.org/angeo-27-2903-2009.pdf |
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Zusammenfassung |
In this study, aerosol optical depth (AOD) measurements, from a MFR sun
photometer operating in Athens, were compared with columnar dust loading
estimations, from the BSC-DREAM model, during identified dust events, in
order to extract the typical specific extinction cross-section for dust over
the area. The selected urban environment of Athens provided us with the
opportunity to investigate the mixing of dust and urban pollution and to
estimate the contribution of the latter. The specific extinction
cross-section for dust at 500 nm was found to be equal to σ500*=0.64±0.04 m2 g,
typical for medium to large
distances from dust sources, with weak wavelength dependence in the visible
and near infrared band (0.4–0.9 μm). The model showed a tendency to
underpredict AOD levels for increasing values of the Ångström
exponent, indicative of fine particles of anthropogenic origin inside the
boundary layer. On average we found an AOD under-prediction of 10–15% for
Ångström exponents in the range of 0 to 1 and 30–40% in the range
of 1 to 2. Additionally, modelled surface concentrations were evaluated
against surface PM10 measurements. Model values were lower than
measured surface concentrations by 30% which, in conjunction with large
scatter, indicated that the effect of the boundary layer anthropogenic
contribution to columnar dust loadings is amplified near the ground. |
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