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| Titel |
Aerosol characterization in Northern Africa, Northeastern Atlantic, Mediterranean Basin and Middle East from direct-sun AERONET observations |
| VerfasserIn |
S. Basart, C. Pérez, E. Cuevas, J. M. Baldasano, G. P. Gobbi |
| 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. 21 ; Nr. 9, no. 21 (2009-11-03), S.8265-8282 |
| Datensatznummer |
250007725
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| Publikation (Nr.) |
 copernicus.org/acp-9-8265-2009.pdf |
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| Zusammenfassung |
| We provide an atmospheric aerosol characterization for North Africa,
Northeastern Atlantic, Mediterranean and Middle East based on the analysis
of quality-assured direct-sun observations of 39 stations of the AErosol
RObotic NETwork (AERONET) which include at least an annual cycle within the
1994–2007 period. We extensively test and apply the recently introduced
graphical method of Gobbi and co-authors to track and discriminate different
aerosol types and quantify the contribution of mineral dust. The method
relies on the combined analysis of the Ångström exponent (α)
and its spectral curvature δα. Plotting data in these coordinates allows to
infer aerosol fine mode radius (Rf) and fractional contribution
(η) to total Aerosol Optical Depth (AOD) and separate AOD growth due to
fine-mode aerosol humidification and/or coagulation from AOD growth due to
the increase in coarse particles or cloud contamination. Our results confirm
the robustness of this graphical method. Large mineral dust is found to be
the most important constituent in Northern Africa and Middle East. Under
specific meteorological conditions, its transport to Southern Europe is
observed from spring to autumn and decreasing with latitude. We observe
"pure Saharan dust" conditions to show AOD>0.7 (ranging up to 5),
α<0.3 and δα<0 corresponding to η<40%
and (Rf)~0.13 μm. Small pollution particles are abundant in
sites close to urban and industrial areas of Continental and Eastern Europe
and Middle East, as well as, important contributions of biomass burning are
observed in the sub-Sahel region in winter. These small aerosols are
associated to AOD<1, α>1.5 and δα~−0.2
corresponding to η>70% and Rf~0.13 μm. Here, dust
mixed with fine pollution aerosols shifts the observations to the region
α<0.75, in which the fine mode contribution is less than 40%. |
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