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| Titel |
Absorbing aerosols: contribution of biomass burning and implications for radiative forcing |
| VerfasserIn |
H. Gadhavi, A. Jayaraman |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 28, no. 1 ; Nr. 28, no. 1 (2010-01-18), S.103-111 |
| Datensatznummer |
250016746
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| Publikation (Nr.) |
 copernicus.org/angeo-28-103-2010.pdf |
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| Zusammenfassung |
Absorbing aerosols supplements the global warming caused by greenhouse
gases. However, unlike greenhouse gases, the effect of absorbing aerosol on
climate is not known with certainty owing to paucity of data. Also,
uncertainty exists in quantifying the contributing factors whether it is
biomass or fossil fuel burning. Based on the observations of absorption
coefficient at seven wavelengths and aerosol optical depth (AOD) at five
wavelengths carried out at Gadanki (13.5° N, 79.2° E), a remote
village in peninsular India, from April to November 2008, as part of the
"Study of Atmospheric Forcing and Responses (SAFAR)" pilot campaign we
discuss seasonal variation of black carbon (BC) concentration and aerosol
optical depth. Also, using spectral information we estimate the fraction of
fossil-fuel and non-fossil fuel contributions to absorption coefficient and
contributions of soot (Black Carbon), non-soot fine mode aerosols and coarse
mode aerosols to AOD.
BC concentration is found to be around 1000 ng/m3 during monsoon months
(JJAS) and around 4000 ng/m3 during pre and post monsoon months.
Non-fossil fuel sources contribute nearly 20% to absorption coefficient
at 880 nm, which increases to 40% during morning and evening hours.
Average AOD is found to be 0.38±0.15, with high values in May and low
in September. Soot contributes nearly 10% to the AOD. This information is
further used to estimate the clear sky aerosol direct radiative forcing. Top
of the atmosphere aerosol radiative forcing varies between −4 to 0 W m−2, except for April when the forcing is positive. Surface level
radiative forcing is between −10 to −20 W m−2. The net radiation
absorbed within the atmosphere is in the range of 9 to 25 W m−2, of
which soot contributes about 80 to 90%. |
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