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| Titel |
A novel methodology for large-scale daily assessment of the direct radiative forcing of smoke aerosols |
| VerfasserIn |
E. T. Sena, P. Artaxo |
| 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. 10 ; Nr. 15, no. 10 (2015-05-20), S.5471-5483 |
| Datensatznummer |
250119737
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| Publikation (Nr.) |
 copernicus.org/acp-15-5471-2015.pdf |
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| Zusammenfassung |
A new methodology was developed for obtaining daily retrievals of the direct
radiative forcing of aerosols (24h-DARF) at the top of the atmosphere (TOA)
using satellite remote sensing. Simultaneous CERES (Clouds and Earth's
Radiant Energy System) shortwave flux at the top of the atmosphere and
MODIS (Moderate Resolution Spectroradiometer) aerosol optical depth (AOD)
retrievals were used. To analyse the impact of forest smoke on the radiation
balance, this methodology was applied over the Amazonia during the peak of
the biomass burning season from 2000 to 2009.
To assess the spatial distribution of the DARF, background smoke-free scenes
were selected. The fluxes at the TOA under clean conditions (Fcl)
were estimated as a function of the illumination geometry (θ0) for
each 0.5° × 0.5° grid cell. The instantaneous DARF
was obtained as the difference between the clean (Fcl (θ0))
and the polluted flux at the TOA measured by CERES in each cell
(Fpol (θ0)). The radiative transfer code SBDART (Santa
Barbara DISORT Radiative Transfer model) was used to expand instantaneous
DARFs to 24 h averages.
This new methodology was applied to assess the DARF both at high temporal
resolution and over a large area in Amazonia. The spatial distribution shows
that the mean 24h-DARF can be as high as −30 W m−2 over some regions.
The temporal variability of the 24h-DARF along the biomass burning season
was also studied and showed large intraseasonal and interannual variability.
We showed that our methodology considerably reduces statistical sources of
uncertainties in the estimate of the DARF, when compared to previous
approaches. DARF assessments using the new methodology agree well with
ground-based measurements and radiative transfer models. This demonstrates
the robustness of the new proposed methodology for assessing the radiative
forcing for biomass burning aerosols. To our knowledge, this is the first
time that satellite remote sensing assessments of the DARF have been compared with
ground-based DARF estimates. |
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