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| Titel |
Automatic monitoring of the effective thermal conductivity of snow in a low-Arctic shrub tundra |
| VerfasserIn |
F. Domine, M. Barrere, D. Sarrazin, S. Morin, L. Arnaud |
| 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. 3 ; Nr. 9, no. 3 (2015-06-22), S.1265-1276 |
| Datensatznummer |
250116815
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| Publikation (Nr.) |
 copernicus.org/tc-9-1265-2015.pdf |
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| Zusammenfassung |
| The effective thermal conductivity of snow, keff, is a critical variable
which determines the temperature gradient in the snowpack and heat exchanges
between the ground and the atmosphere through the snow. Its accurate
knowledge is therefore required to simulate snow metamorphism, the ground
thermal regime, permafrost stability, nutrient recycling and vegetation
growth. Yet, few data are available on the seasonal evolution of snow
thermal conductivity in the Arctic. We have deployed heated needle probes on
low-Arctic shrub tundra near Umiujaq, Quebec, (N56°34';
W76°29') and monitored automatically the evolution of keff
for two consecutive winters, 2012–2013 and 2013–2014, at four heights in the
snowpack. Shrubs are 20 cm high dwarf birch. Here, we develop an algorithm
for the automatic determination of keff from the heating curves and
obtain 404 keff values. We evaluate possible errors and biases
associated with the use of the heated needles. The time evolution of
keff is very different for both winters. This is explained by comparing
the meteorological conditions in both winters, which induced different
conditions for snow metamorphism. In particular, important melting events in
the second year increased snow hardness, impeding subsequent densification
and increase in thermal conductivity. We conclude that shrubs have very
important impacts on snow physical evolution: (1) shrubs absorb light and
facilitate snow melt under intense radiation; (2) the dense twig network of
dwarf birch prevent snow compaction, and therefore keff increase; (3) the
low density depth hoar that forms within shrubs collapsed in late winter,
leaving a void that was not filled by snow. |
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