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| Titel |
Modeling the impact of wintertime rain events on the thermal regime of permafrost |
| VerfasserIn |
S. Westermann, J. Boike, M. Langer, T. V. Schuler, B. Etzelmüller |
| 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 ; 5, no. 4 ; Nr. 5, no. 4 (2011-10-26), S.945-959 |
| Datensatznummer |
250002752
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| Publikation (Nr.) |
 copernicus.org/tc-5-945-2011.pdf |
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| Zusammenfassung |
| In this study, we present field measurements and numerical process modeling
from western Svalbard showing that the ground surface temperature below the
snow is impacted by strong wintertime rain events. During such events, rain
water percolates to the bottom of the snow pack, where it freezes and
releases latent heat. In the winter season 2005/2006, on the order of 20 to
50% of the wintertime precipitation fell as rain, thus confining the
surface temperature to close to 0 °C for several weeks. The measured
average ground surface temperature during the snow-covered period is
−0.6 °C, despite of a snow surface temperature of on average
−8.5 °C. For the considered period, the temperature threshold below
which permafrost is sustainable on long timescales is exceeded. We present a
simplified model of rain water infiltration in the snow coupled to a
transient permafrost model. While small amounts of rain have only minor
impact on the ground surface temperature, strong rain events have a
long-lasting impact. We show that consecutively applying the conditions
encountered in the winter season 2005/2006 results in the formation of an
unfrozen zone in the soil after three to five years, depending on the
prescribed soil properties. If water infiltration in the snow is disabled in
the model, more time is required for the permafrost to reach a similar state
of degradation. |
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