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| Titel |
An AeroCom assessment of black carbon in Arctic snow and sea ice |
| VerfasserIn |
C. Jiao, M. G. Flanner, Y. Balkanski, S. E. Bauer, N. Bellouin, T. K. Berntsen, H. Bian, K. S. Carslaw, M. Chin, N. De Luca, T. Diehl, S. J. Ghan, T. Iversen, A. Kirkevåg, D. Koch, X. Liu, G. W. Mann, J. E. Penner, G. Pitari, M. Schulz, Ø. Seland, R. B. Skeie, S. D. Steenrod, P. Stier, T. Takemura, K. Tsigaridis, T. van Noije, Y. Yun, K. Zhang |
| 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 ; 14, no. 5 ; Nr. 14, no. 5 (2014-03-07), S.2399-2417 |
| Datensatznummer |
250118467
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| Publikation (Nr.) |
 copernicus.org/acp-14-2399-2014.pdf |
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| Zusammenfassung |
| Though many global aerosols models prognose surface deposition, only a
few models have been used to directly simulate the radiative effect
from black carbon (BC) deposition to snow and sea ice. Here, we apply
aerosol deposition fields from 25 models contributing to two phases of
the Aerosol Comparisons between Observations and Models (AeroCom)
project to simulate and evaluate within-snow BC concentrations and
radiative effect in the Arctic. We accomplish this by driving the
offline land and sea ice components of the Community Earth System
Model with different deposition fields and meteorological conditions
from 2004 to 2009, during which an extensive field campaign of BC
measurements in Arctic snow occurred. We find that models generally
underestimate BC concentrations in snow in northern Russia and Norway,
while overestimating BC amounts elsewhere in the Arctic. Although
simulated BC distributions in snow are poorly correlated with
measurements, mean values are reasonable. The multi-model mean (range)
bias in BC concentrations, sampled over the same grid cells, snow
depths, and months of measurements, are −4.4 (−13.2 to
+10.7) ng g−1 for an earlier phase of AeroCom models (phase I), and +4.1 (−13.0 to
+21.4) ng g−1 for a more recent phase of AeroCom models (phase II),
compared to the observational mean of 19.2 ng g−1.
Factors determining model BC concentrations in Arctic
snow include Arctic BC emissions, transport of extra-Arctic aerosols, precipitation,
deposition efficiency of aerosols within the Arctic, and meltwater
removal of particles in snow. Sensitivity studies show that the
model–measurement evaluation is only weakly affected by meltwater
scavenging efficiency because most measurements were conducted in
non-melting snow. The Arctic (60–90° N) atmospheric residence time for BC in
phase II models ranges from 3.7 to 23.2 days, implying large
inter-model variation in local BC deposition efficiency. Combined with
the fact that most Arctic BC deposition originates from extra-Arctic
emissions, these results suggest that aerosol removal processes are a
leading source of variation in model performance. The multi-model
mean (full range) of Arctic radiative effect from BC in snow
is 0.15 (0.07–0.25) W m−2 and 0.18 (0.06–0.28) W m−2 in phase I and phase II models, respectively. After correcting for model biases
relative to observed BC concentrations in different regions of the
Arctic, we obtain a multi-model mean Arctic radiative effect of
0.17 W m−2 for the combined AeroCom ensembles. Finally, there is a
high correlation between modeled BC concentrations sampled over the
observational sites and the Arctic as a whole, indicating that the
field campaign provided a reasonable sample of the Arctic. |
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