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| Titel |
Aerosol direct radiative effect in the Po Valley region derived from AERONET measurements |
| VerfasserIn |
M. Clerici, F. Mélin |
| 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 ; 8, no. 16 ; Nr. 8, no. 16 (2008-08-27), S.4925-4946 |
| Datensatznummer |
250006343
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| Publikation (Nr.) |
 copernicus.org/acp-8-4925-2008.pdf |
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| Zusammenfassung |
| The aerosol direct radiative effect (ADRE) affecting the Po Valley
and the adjacent North Adriatic Sea is studied using 10-year
series of measurements collected at two AERONET sites located in
the western part of the Valley (Ispra), and on a platform (AAOT)
offshore Venice. This region is characterized by a high, mostly
continental, aerosol load with comparable average aerosol optical
thickness τa at both locations (0.21 at 500 nm) and more
absorbing aerosols at Ispra. A dynamic aerosol model accounting
for the changes in scattering phase function with τa is
used for radiative transfer calculations, together with boundary
conditions representative of terrestrial and marine surfaces. A
sensitivity analysis allows the construction of an error budget
for the daily ADRE estimates, found to be of the order of 20% and
mostly due to uncertainties on aerosol single scattering albedo
and τa. The daily radiative efficiencies, normalized by
τa at 500 nm, increase from December to June, from −17 to
−24 W m−2 τa−1 at top-of-atmosphere (TOA) and −33
to −72 W m−2 τa−1 at surface for the Po Valley,
and from −15 to −32 (TOA) and −35 to −65 W m−2
τa−1 (surface) for the AAOT site. The average of
log-transformed ADRE for TOA, surface and atmosphere are −5.2,
−12.2 and +6.8 W m−2 for the Po Valley case, and −6.5, −13.0
and +6.5 W m−2 for the AAOT site but these values can be much
higher for individual days. Concurrent clear-sky days give
indications on the regional atmospheric heating spatial gradients.
Differences between the atmospheric ADRE at the two locations
average 6.3 W m−2 with a gradient positive towards the inner
valley in 65% of the cases. This study confirms the importance of
duly considering the radiative impact of aerosols on the regional climate. |
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