Thermal regime of rock and its relation to snow cover in steep alpine rock walls: gemsstock, central swiss alps

Abstract

Snow cover influences the thermal regime and stability of frozen rock walls. In this study, we investigate and model the impact of the spatially variable snow cover on the thermal regime of steep permafrost rock walls. This is necessary for a more detailed understanding of the thermal and mechanical processes causing changes in rock temperature and in the ice and water contents of frozen rock, which possibly lead to rock wall instability. To assess the temporal and spatial evolution and influence of the snow, detailed measurements have been carried out at two selected points in steep north‐ and south‐facing rock walls since 2012. In parallel, the one‐dimensional energy balance model SNOWPACK is used to simulate the effects of snow cover on the thermal regime of the rock walls. For this, a multi‐method approach with high temporal resolution is applied, combining meteorological, borehole rock temperature and terrain parameter measurements. To validate the results obtained for the ground thermal regime and the seasonally varying snowpack, the model output is compared with near‐surface rock temperature measurements and remote snow cover observations.

No decrease of snow depth at slope angles up to 70° was observed in rough terrain due to micro‐topographic structures. Strong contrasts in rock temperatures between north‐ and south‐facing slopes are due to differences in solar radiation, slope angle and the timing and depth of the snow cover.

SNOWPACK proved to be useful for modelling snow cover–rock interactions in smooth, homogenous rock slopes.

Key words:

• snow distribution
• rock wall temperature
• thermal modelling
• SNOWPACK

Acknowledgements

This project is funded by the Swiss National Science Foundation (DACH Project no. 200021E‐135531). We thank our project partners Michael Krautblatter, Daniel Dräbing and Stephan Gruber. Carlo Danioth and Team, the SLF Electronics and Mechanics team, Thomas Grünewald, Marc‐Olivier Schmid, Lisa Dreier, and Fabienne Stucki all provided valuable support in the field and with the development of measurement devices. Michael Lehning, Charles Fierz, Walter Steinkogler, Edgar Schmucki, Matthias Keller, Tobias Jonas, Christoph Marty and Jan Magnusson are thanked for their support with SNOWPACK and other software.

Additional information

Notes on contributors

Anna Haberkorn

Anna Haberkorn, Marcia Phillips, Robert Kenner, Hansueli Rhyner, Mathias Bavay, WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH‐7260 Davos Dorf, Switzerland. E‐mail: [email protected], [email protected], [email protected], [email protected], [email protected]

Marcia Phillips

Anna Haberkorn, Marcia Phillips, Robert Kenner, Hansueli Rhyner, Mathias Bavay, WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH‐7260 Davos Dorf, Switzerland. E‐mail: [email protected], [email protected], [email protected], [email protected], [email protected]

Robert Kenner

Anna Haberkorn, Marcia Phillips, Robert Kenner, Hansueli Rhyner, Mathias Bavay, WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH‐7260 Davos Dorf, Switzerland. E‐mail: [email protected], [email protected], [email protected], [email protected], [email protected]

Hansueli Rhyner

Anna Haberkorn, Marcia Phillips, Robert Kenner, Hansueli Rhyner, Mathias Bavay, WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH‐7260 Davos Dorf, Switzerland. E‐mail: [email protected], [email protected], [email protected], [email protected], [email protected]

Mathias Bavay

Anna Haberkorn, Marcia Phillips, Robert Kenner, Hansueli Rhyner, Mathias Bavay, WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH‐7260 Davos Dorf, Switzerland. E‐mail: [email protected], [email protected], [email protected], [email protected], [email protected]

Stephan P. Galos

Stephan P. Galos, Institute of Meteorology and Geophysics, University of Innsbruck, Innrain 52f, A‐6020 Innsbruck, Austria E‐mail: [email protected]

Martin Hoelzle

Martin Hoelzle, Unit of Geography, Department of Geosciences, University of Fribourg, Chemin du Musée 4, CH‐1700 Fribourg, Switzerland. E‐mail: [email protected]