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| Titel |
Aerosol radiative forcing during African desert dust events (2005–2010) over Southeastern Spain |
| VerfasserIn |
A. Valenzuela, F. J. Olmo, H. Lyamani, M. Antón, A. Quirantes, L. Alados-Arboledas |
| 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 ; 12, no. 21 ; Nr. 12, no. 21 (2012-11-06), S.10331-10351 |
| Datensatznummer |
250011569
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| Publikation (Nr.) |
 copernicus.org/acp-12-10331-2012.pdf |
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| Zusammenfassung |
| The daily (24 h) averages of the aerosol radiative forcing (ARF) at the
surface and the top of the atmosphere (TOA) were calculated during desert
dust events over Granada (southeastern Spain) from 2005 to 2010. A radiative
transfer model (SBDART) was utilized to simulate the solar irradiance values
(0.31–2.8 μm) at the surface and TOA, using as input
aerosol properties retrieved from CIMEL sun photometer measurements via an
inversion methodology that uses the sky radiance measurements in principal
plane configuration and a spheroid particle shape approximation. This
inversion methodology was checked by means of simulated data from aerosol
models, and the derived aerosol properties were satisfactorily compared
against well-known AERONET products. Good agreement was found over a common
spectral interval (0.2–4.0 μm) between the simulated
SBDART global irradiances at surface and those provided by AERONET. In
addition, simulated SBDART solar global irradiances at the surface have been
successfully validated against CM-11 pyranometer measurements. The comparison
indicates that the radiative transfer model slightly overestimates (mean bias
of 3%) the experimental solar global irradiance. These results show that
the aerosol optical properties used to estimate ARF represent appropriately
the aerosol properties observed during desert dust outbreak over the study
area. The ARF mean monthly values computed during desert dust events ranged
from −13 ± 8 W m−2 to −34 ± 15 W m−2 at
surface, from −4 ± 3 W m−2 to −13 ± 7 W m−2 at
TOA and from +6 ± 4 to +21 ± 12 W m−2 in the atmosphere.
We have checked if the differences found in aerosol optical properties among
desert dust sectors translate to differences in ARF. The mean ARF at
surface (TOA) were −20 ± 12 (−5 ± 5) W m−2,
−21 ± 9 (−7 ± 5) W m−2 and −18 ± 9
(−6 ± 5) W m−2 for sector A (northern Morocco; northwestern
Algeria), sector B (western Sahara, northwestern Mauritania and southwestern
Algeria), and sector C (eastern Algeria, Tunisia), respectively. The
Kolmogorov-Smirnov statistical test revealed that daily {ARF} values at TOA
for sector A were significantly different from the other two sectors, likely
as a result of the lower values of single scattering albedo obtained for
sector A. The mean values of aerosol radiative forcing efficiency at surface
(TOA) were −74 ± 12 W m−2 (−17 ± 7 W m−2) for
sector A, −70 ± 14 W m−2 (−20 ± 9 W m−2) for
sector B, and −65 ± 16 W m−2 (−22 ± 10 W m−2)
for sector C, and thus comparable between the three sectors in all seasons. |
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