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| Titel |
Summertime evolution of snow specific surface area close to the surface on the Antarctic Plateau |
| VerfasserIn |
Q. Libois, G. Picard, L. Arnaud, M. Dumont, M. Lafaysse, S. Morin, E. Lefebvre |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 9, no. 6 ; Nr. 9, no. 6 (2015-12-15), S.2383-2398 |
| Datensatznummer |
250116886
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| Publikation (Nr.) |
 copernicus.org/tc-9-2383-2015.pdf |
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| Zusammenfassung |
| On the Antarctic Plateau, snow specific surface area (SSA) close to
the surface shows complex variations at daily to seasonal scales which
affect the surface albedo and in turn the surface energy budget of the
ice sheet. While snow metamorphism, precipitation and strong wind
events are known to drive SSA variations, usually in opposite ways,
their relative contributions remain unclear. Here, a comprehensive set
of SSA observations at Dome C is analysed with respect to
meteorological conditions to assess the respective roles of these
factors. The results show an average 2-to-3-fold SSA decrease
from October to February in the topmost 10 cm in response to
the increase of air temperature and absorption of solar radiation in
the snowpack during spring and summer. Surface SSA is also
characterized by significant daily to weekly variations due to the
deposition of small crystals with SSA up to 100 m2 kg−1
onto the surface during snowfall and blowing snow events. To
complement these field observations, the detailed snowpack model
Crocus is used to simulate SSA, with the intent to further investigate
the previously found correlation between interannual variability of
summer SSA decrease and summer precipitation amount. To this end,
some Crocus parameterizations have been adapted to Dome C conditions, and
the model was forced by ERA-Interim reanalysis. It successfully
matches the observations at daily to seasonal timescales, except for the
few cases when snowfalls are not captured by the reanalysis. On the
contrary, the interannual variability of summer SSA decrease is
poorly simulated when compared to 14 years of microwave
satellite data sensitive to the near-surface SSA. A simulation with
disabled summer precipitation confirms the weak influence in the model
of the precipitation on metamorphism, with only 6 %
enhancement. However, we found that disabling strong wind events in the
model is sufficient to reconciliate the simulations with the
observations. This suggests that Crocus reproduces well the
contributions of metamorphism and precipitation on surface SSA, but
snow compaction by the wind might be overestimated in the model. |
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