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Université de Fribourg

Twenty years of European mountain permafrost dynamics—the PACE legacy

Etzelmüller, Bernd ; Guglielmin, Mauro ; Hauck, Christian ; Hilbich, Christin ; Hoelzle, Martin ; Isaksen, Ketil ; Noetzli, Jeanette ; Oliva, Marc ; Ramos, Miguel

In: Environmental Research Letters, 2020, vol. 15, no. 10, p. 104070

This paper reviews and analyses the past 20 years of change and variability of European mountain permafrost in response to climate change based on time series of ground temperatures along a south–north transect of deep boreholes from Sierra Nevada in Spain (37°N) to Svalbard (78°N), established between 1998 and 2000 during the EU-funded PACE (Permafrost and Climate in Europe) project. In...

Université de Fribourg

A monitoring system for spatiotemporal electrical self-potential measurements in cryospheric environments

Weigand, Maximilian ; Wagner, Florian M. ; Limbrock, Jonas K. ; Hilbich, Christin ; Hauck, Christian ; Kemna, Andreas

In: Geoscientific Instrumentation, Methods and Data Systems, 2020, vol. 9, no. 2020-2, p. 317–336

Climate-induced warming increasingly leads to degradation of high-alpine permafrost. In order to develop early warning systems for imminent slope destabilization, knowledge about hydrological flow processes in the subsurface is urgently needed. Due to the fast dynamics associated with slope failures, non- or minimally invasive methods are required for inexpensive and timely characterization...

Université de Fribourg

Direct observations of a three million cubic meter rock-slope collapse with almost immediate initiation of ensuing debris flows

Walter, Fabian ; Amann, Florian ; Kos, Andrew ; Kenner, Robert ; Phillips, Marcia ; Preux, Antoine de ; Huss, Matthias ; Tognacca, Christian ; Clinton, John ; Diehl, Tobias ; Bonanomi, Yves

In: Geomorphology, 2020, vol. 351, p. 106933

Catastrophic collapse of large rock slopes ranks as one of the most hazardous natural phenomena in mountain landscapes. The cascade of events, from rock- slope failure, to rock avalanche and the near-immediate release of debris flows has not previously been described from direct observations. We report on the 2017, 3.0 × 106 m3 failure on Pizzo Cengalo in Switzerland, which led to human...

Université de Fribourg

Petrophysical joint inversion applied to alpine permafrost field sites to image subsurface ice, water, air, and rock contents

Mollaret, Coline ; Wagner, Florian M. ; Hilbich, Christin ; Scapozza, Cristian ; Hauck, Christian

In: Frontiers in Earth Sc-ience, 2020, vol. 8, p. -

Quantification of ground ice is crucial for understanding permafrost systems and modeling their ongoing degradation. The volumetric ice content is however rarely estimated in permafrost studies, as it is particularly difficult to retrieve. Standard borehole temperature monitoring is unable to provide any ice content estimation, whereas non-invasive geophysical techniques, such as refraction ...

Université de Fribourg

Continuous and autonomous snow water equivalent measurements by a cosmic ray sensor on an alpine glacier

Gugerli, Rebecca ; Salzmann, Nadine ; Huss, Matthias ; Desilets, Darin

In: The Cryosphere, 2019, vol. 13, no. 12, p. 3413–3434

Snow water equivalent (SWE) measurements of seasonal snowpack are crucial in many research fields. Yet accurate measurements at a high temporal resolution are difficult to obtain in high mountain regions. With a cosmic ray sensor (CRS), SWE can be inferred from neutron counts. We present the analyses of temporally continuous SWE measurements by a CRS on an alpine glacier in Switzerland...

Université de Fribourg

Recent glacier and lake changes in High Mountain Asia and their relation to precipitation changes

Treichler, Désirée ; Kääb, Andreas ; Salzmann, Nadine ; Xu, Chong-Yu

In: The Cryosphere, 2019, vol. 13, no. 11, p. 2977–3005

We present an updated, spatially resolved estimate of 2003–2008 glacier surface elevation changes for the entire region of High Mountain Asia (HMA) from ICESat laser altimetry data. The results reveal a diverse pattern that is caused by spatially greatly varying glacier sensitivity, in particular to precipitation availability and changes. We introduce a spatially resolved zonation where...

Université de Fribourg

Quantitative imaging of water, ice and air in permafrost systems through petrophysical joint inversion of seismic refraction and electrical resistivity data

Wagner, Florian ; Mollaret, Coline ; Günther, Thomas ; Kemna, Andreas

In: Geophysical Journal International, 2019, vol. 219, no. 3, p. 1866–1875

Quantitative estimation of pore fractions filled with liquid water, ice and air is crucial for a process-based understanding of permafrost and its hazard potential upon climate- induced degradation. Geophysical methods offer opportunities to image distributions of permafrost constituents in a non-invasive manner. We present a method to jointly estimate the volumetric fractions of liquid water,...

Université de Fribourg

Distinguishing ice-rich and ice-poor permafrost to map ground temperatures and ground ice occurrence in the Swiss Alps

Kenner, Robert ; Noetzli, Jeannette ; Hoelzle, Martin ; Raetzo, Hugo ; Phillips, Marcia

In: The Cryosphere, 2019, vol. 13, no. 7, p. 1925–1941

Mountain permafrost is invisible, and mapping it is still a challenge. Available permafrost distribution maps often overestimate the permafrost extent and include large permafrost-free areas in their permafrost zonation. In addition, the representation of the lower belt of permafrost consisting of ice-rich features such as rock glaciers or ice-rich talus slopes can be challenging. These...