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| Titel |
The regime of aerosol asymmetry parameter over Europe, the Mediterranean and the Middle East based on MODIS satellite data: evaluation against surface AERONET measurements |
| VerfasserIn |
M. B. Korras-Carraca, N. Hatzianastassiou, C. Matsoukas, A. Gkikas, C. D. Papadimas |
| 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 ; 15, no. 22 ; Nr. 15, no. 22 (2015-11-26), S.13113-13132 |
| Datensatznummer |
250120187
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| Publikation (Nr.) |
 copernicus.org/acp-15-13113-2015.pdf |
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| Zusammenfassung |
Atmospheric particulates are a significant forcing agent for the radiative
energy budget of the Earth–atmosphere system. The particulates' interaction
with radiation, which defines their climate effect, is strongly dependent on
their optical properties. In the present work, we study one of the most
important optical properties of aerosols, the asymmetry parameter
(gaer), over sea surfaces of the region comprising North Africa, the
Arabian Peninsula, Europe, and the Mediterranean Basin. These areas are of
great interest, because of the variety of aerosol types they host, both
anthropogenic and natural. Using satellite data from the collection 051 of
MODIS (Moderate Resolution Imaging Spectroradiometer, Terra and Aqua), we
investigate the spatiotemporal characteristics of the asymmetry parameter.
We generally find significant spatial variability, with larger values over
regions dominated by larger size particles, e.g., outside the Atlantic coasts
of northwestern Africa, where desert-dust outflow takes place. The
gaer values tend to decrease with increasing wavelength, especially
over areas dominated by small particulates. The intra-annual variability is
found to be small in desert-dust areas, with maximum values during summer,
while in all other areas larger values are reported during the cold season
and smaller during the warm. Significant intra-annual and inter-annual
variability is observed around the Black Sea. However, the inter-annual
trends of gaer are found to be generally small.
Although satellite data have the advantage of broad geographical coverage,
they have to be validated against reliable surface measurements. Therefore,
we compare satellite-measured values with gaer values measured at
69 stations of the global surface AERONET (Aerosol Robotic Network), located
within our region of interest. This way, we provide some insight on the
quality and reliability of MODIS data. We report generally better agreement
at the wavelength of 860 nm (correlation coefficient R up to 0.47), while
at all wavelengths the results of the comparison were better for spring and
summer. |
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