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| Titel |
Refreezing on the Greenland ice sheet: a comparison of parameterizations |
| VerfasserIn |
C. H. Reijmer, M. R. Broeke, X. Fettweis, J. Ettema, L. B. Stap |
| 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 ; 6, no. 4 ; Nr. 6, no. 4 (2012-07-11), S.743-762 |
| Datensatznummer |
250003689
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| Publikation (Nr.) |
 copernicus.org/tc-6-743-2012.pdf |
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| Zusammenfassung |
| Retention and refreezing of meltwater are acknowledged to be important
processes for the mass budget of polar glaciers and ice sheets. Several
parameterizations of these processes exist for use in energy and mass
balance models. Due to a lack of direct observations, validation of these
parameterizations is difficult. In this study we compare a set of 6 refreezing
parameterizations against output of two Regional Climate Models (RCMs)
coupled to an energy balance snow model, the Regional Atmospheric Climate
Model (RACMO2) and the Modèle Atmosphérique Régional (MAR),
applied to the Greenland ice sheet. In both RCMs, refreezing is explicitly
calculated in a snow model that calculates vertical profiles of temperature,
density and liquid water content. Between RACMO2 and MAR, the ice sheet-integrated
amount of refreezing differs by only 4.9 mm w.e yr−1 (4.5 %), and
the temporal and spatial variability are very similar.
For consistency, the parameterizations are forced with output (surface temperature,
precipitation and melt) of the RCMs.
For the ice sheet-integrated amount of refreezing and its inter-annual variations,
all parameterizations give similar results, especially after some tuning. However,
the spatial distributions differ significantly and the spatial correspondence between
the RCMs is better than with any of the parameterizations. Results are especially
sensitive to the choice of the depth of the thermally active layer, which determines
the cold content of the snow in most parameterizations. These results are
independent of which RCM is used to force the parameterizations. |
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