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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Volume 9, issue 5
The Cryosphere, 9, 1819-1830, 2015
https://doi.org/10.5194/tc-9-1819-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
The Cryosphere, 9, 1819-1830, 2015
https://doi.org/10.5194/tc-9-1819-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 17 Sep 2015

Research article | 17 Sep 2015

Thermal energy in dry snow avalanches

W. Steinkogler1,2, B. Sovilla1, and M. Lehning1,2 W. Steinkogler et al.
  • 1WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland
  • 2CRYOS, School of Architecture, Civil and Environmental Engineering, EPFL, Lausanne, Switzerland

Abstract. Avalanches can exhibit many different flow regimes from powder clouds to slush flows. Flow regimes are largely controlled by the properties of the snow released and entrained along the path. Recent investigations showed the temperature of the moving snow to be one of the most important factors controlling the mobility of the flow. The temperature of an avalanche is determined by the temperature of the released and entrained snow but also increases by frictional processes with time. For three artificially released avalanches, we conducted snow profiles along the avalanche track and in the deposition area, which allowed quantifying the temperature of the eroded snow layers. This data set allowed to calculate the thermal balance, from release to deposition, and to discuss the magnitudes of different sources of thermal energy of the avalanches. For the investigated dry avalanches, the thermal energy increase due to friction was mainly depending on the effective elevation drop of the mass of the avalanche with a warming of approximately 0.3 °C per 100 vertical metres. Contrarily, the temperature change due to entrainment varied for the individual avalanches, from −0.08 to 0.3 °C, and depended on the temperature of the snow along the path and the erosion depth. Infrared radiation thermography (IRT) was used to assess the surface temperature before, during and just after the avalanche with high spatial resolution. This data set allowed to identify the warmest temperatures to be located in the deposits of the dense core. Future research directions, especially for the application of IRT, in the field of thermal investigations in avalanche dynamics are discussed.

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Infrared radiation thermography (IRT) was used to assess the surface temperature of avalanches with high spatial resolution. Thermal energy increase due to friction was mainly depending on the elevation drop of the avalanche. Warming due to entrainment was very specific to the individual avalanche and depends on the temperature of the snow along the path and the erosion depth. The warmest temperatures were located in the deposits of the dense core.
Infrared radiation thermography (IRT) was used to assess the surface temperature of avalanches...
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