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| Titel |
The distribution of snow black carbon observed in the Arctic and compared to the GISS-PUCCINI model |
| VerfasserIn |
T. Dou, C. Xiao, D. T. Shindell  , J. Liu, K. Eleftheriadis, J. Ming, D. Qin |
| 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. 17 ; Nr. 12, no. 17 (2012-09-07), S.7995-8007 |
| Datensatznummer |
250011430
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| Publikation (Nr.) |
 copernicus.org/acp-12-7995-2012.pdf |
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| Zusammenfassung |
| In this study, we evaluate the ability of the latest NASA GISS
composition-climate model, GISS-E2-PUCCINI, to simulate the spatial
distribution of snow BC (sBC) in the Arctic relative to present-day
observations. Radiative forcing due to BC deposition onto Arctic snow and
sea ice is also estimated. Two sets of model simulations are analyzed, where
meteorology is linearly relaxed towards National Centers for Environmental
Prediction (NCEP) and towards NASA Modern Era Reanalysis for Research and
Applications (MERRA) reanalyses. Results indicate that the modeled
concentrations of sBC are comparable with present-day observations in and
around the Arctic Ocean, except for apparent underestimation at a few sites
in the Russian Arctic. That said, the model has some biases in its simulated
spatial distribution of BC deposition to the Arctic. The simulations from
the two model runs are roughly equal, indicating that discrepancies between
model and observations come from other sources. Underestimation of biomass
burning emissions in Northern Eurasia may be the main cause of the low
biases in the Russian Arctic. Comparisons of modeled aerosol BC (aBC) with
long-term surface observations at Barrow, Alert, Zeppelin and Nord stations
show significant underestimation in winter and spring concentrations in the
Arctic (most significant in Alaska), although the simulated seasonality of
aBC has been greatly improved relative to earlier model versions. This is
consistent with simulated biases in vertical profiles of aBC, with
underestimation in the lower and middle troposphere but overestimation in
the upper troposphere and lower stratosphere, suggesting that the wet
removal processes in the current model may be too weak or that vertical
transport is too rapid, although the simulated BC lifetime seems reasonable.
The combination of observations and modeling provides a comprehensive
distribution of sBC over the Arctic. On the basis of this distribution, we
estimate the decrease in snow and sea ice albedo and the resulting radiative
forcing. We suggest that the albedo reduction due to BC deposition presents
significant space-time variations, with highest mean reductions of 1.25%
in the Russian Arctic, which are much larger than those in other Arctic
regions (0.39% to 0.64%). The averaged value over the Arctic north of
66° N is 0.4–0.6% during spring, leading to regional surface
radiative forcings of 0.7, 1.1 and 1.0 W m−2 in spring 2007, 2008 and
2009, respectively. |
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