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Université de Fribourg

Geomorphic response to the lateglacial–holocene transition in high alpine regions (Sanetsch pass, Swiss alps)

Serra, Elena ; Valla, Pierre G. ; Gribenski, Natacha ; Guedes Magrani, Fabio ; Carcaillet, Julien ; Delaloye, Reynald ; Grobéty, Bernard ; Braillard, Luc

In: Boreas, 2020, p. bor.12480

Several palaeoclimatic archives have documented the pronounced climatic and environmental change associated with the Lateglacial–Holocene transition in the European Alps. However, the geomorphic response to this major environmental transition has only been punctually investigated. In this study, we propose a detailed reconstruction of post‐Last Glacial Maximum palaeoenvironmental...

Université de Fribourg

Seismic monitoring in the Gugla rock glacier (Switzerland): ambient noise correlation, microseismicity and modelling

Guillemot, Antoine ; Helmstetter, Agnès ; Larose, Éric ; Baillet, Laurent ; Garambois, Stéphane ; Mayoraz, Raphaël ; Delaloye, Reynald

In: Geophysical Journal International, 2020, vol. 221, no. 3, p. 1719–1735

A network of seismometers has been installed on the Gugla rock glacier since October 2015 to estimate seismic velocity changes and detect microseismicity. These two processes are related to mechanical and structural variations occurring within the rock glacier. Seismic monitoring thus allows a better understanding of the dynamics of rock glaciers throughout the year. We observed seasonal...

Université de Fribourg

Monitoring rock glacier kinematics with satellite synthetic aperture radar

Strozzi, Tazio ; Caduff, Rafael ; Jones, Nina ; Barboux, Chloé ; Delaloye, Reynald ; Bodin, Xavier ; Kääb, Andreas ; Mätzler, Eva ; Schrott, Lothar

In: Remote Sensing, 2020, vol. 12, no. 3, p. 559

Active rock glaciers represent the best visual expression of mountain permafrost that can be mapped and monitored directly using remotely sensed data. Active rock glaciers are bodies that consist of a perennially frozen ice/rock mixture and express a distinct flow-like morphology indicating downslope permafrost creep movement. Annual rates of motion have ranged from a few millimeters to...

Université de Fribourg

Mountain permafrost degradation documented through a network of permanent electrical resistivity tomography sites

Mollaret, Coline ; Hilbich, Christin ; Pellet, Cécile ; Flores-Orozco, Adrian ; Delaloye, Reynald ; Hauck, Christian

In: The Cryosphere, 2019, vol. 13, no. 10, p. 2557–2578

Mountain permafrost is sensitive to climate change and is expected to gradually degrade in response to the ongoing atmospheric warming trend. Long-term monitoring of the permafrost thermal state is a key task, but problematic where temperatures are close to 0 ∘C because the energy exchange is then dominantly related to latent heat effects associated with phase change (ice–water), rather...

Université de Fribourg

Northern Hemisphere permafrost map based on TTOP modelling for 2000–2016 at 1 km2 scale

Obu, Jaroslav ; Westermann, Sebastian ; Bartsch, Annett ; Berdnikov, Nikolai ; Christiansen, Hanne H. ; Dashtseren, Avirmed ; Delaloye, Reynald ; Elberling, Bo ; Etzelmüller, Bernd ; Kholodov, Alexander ; Khomutov, Artem ; Kääb, Andreas ; Leibman, Marina O. ; Lewkowicz, Antoni G. ; Panda, Santosh K. ; Romanovskyh, Vladimir ; Wayk, Robert G. ; Westergaard-Nielsen, Andreas ; Wu, Tonghua ; Yamkhin, Jambaljav ; Zou, Defu

In: Earth-Science Reviews, 2019, vol. 193, p. 299–316

Permafrost is a key element of the cryosphere and an essential climate variable in the Global Climate Observing System. There is no remote-sensing method available to reliably monitor the permafrost thermal state. To estimate permafrost distribution at a hemispheric scale, we employ an equilibrium state model for the temperature at the top of the permafrost (TTOP model) for the 2000–2016...

Université de Fribourg

Permafrost is warming at a global scale

Biskaborn, Boris K. ; Smith, Sharon L. ; Noetzli, Jeannette ; Matthes, Heidrun ; Vieira, Gonçalo ; Streletskiy, Dmitry A. ; Schoeneich, Philippe ; Romanovsky, Vladimir E. ; Lewkowicz, Antoni G. ; Abramov, Andrey ; Allard, Michel ; Boike, Julia ; Cable, William L. ; Christiansen, Hanne H. ; Delaloye, Reynald ; Diekmann, Bernhard ; Drozdov, Dmitry ; Etzelmüller, Bernd ; Grosse, Guido ; Guglielmin, Mauro ; Ingeman-Nielsen, Thomas ; Isaksen, Ketil ; Ishikawa, Mamoru ; Johansson, Margareta ; Johannsson, Halldor ; Joo, Anseok ; Kaverin, Dmitry ; Kholodov, Alexander ; Konstantinov, Pavel ; Kröger, Tim ; Lambiel, Christophe ; Lanckman, Jean-Pierre ; Luo, Dongliang ; Malkova, Galina ; Meiklejohn, Ian ; Moskalenko, Natalia ; Oliva, Marc ; Phillips, Marcia ; Ramos, Miguel ; Sannel, A. Britta K. ; Sergeev, Dmitrii ; Seybold, Cathy ; Skryabin, Pavel ; Vasiliev, Alexander ; Wu, Qingbai ; Yoshikawa, Kenji ; Zheleznyak, Mikhail ; Lantuit, Hugues

In: Nature Communications, 2019, vol. 10, no. 1, p. 264

Permafrost warming has the potential to amplify global climate change, because when frozen sediments thaw it unlocks soil organic carbon. Yet to date, no globally consistent assessment of permafrost temperature change has been compiled. Here we use a global data set of permafrost temperature time series from the Global Terrestrial Network for Permafrost to evaluate temperature change across...

Université de Fribourg

The reproducibility of SfM algorithms to produce detailed Digital Surface Models: the example of PhotoScan applied to a high-alpine rock glacier

Hendrickx, Hanne ; Vivero, Sebastián ; Cock, Laure De ; De Wit, Bart ; De Maeyer, Philippe ; Lambiel, Christophe ; Delaloye, Reynald ; Nyssen, Jan ; Frankl, Amaury

In: Remote Sensing Letters, 2019, vol. 10, no. 1, p. 11–20

In geomorphology, PhotoScan is a software that is used to produce Digital Surface Models (DSMs). It constructs 3D environments from 2D imagery (often taken by Unmanned Aerial Vehicles (UAV)) based on Structure-from-Motion (SfM) and Multi- View Stereo (MVS) principles. However, unpublished computer-vision algorithms used, contain random elements which can affect the accuracy of the outputs. For...

Université de Fribourg

Mapping and quantifying sediment transfer between the front of rapidly moving rock glaciers and torrential gullies

Kummert, Mario ; Delaloye, Reynald

In: Geomorphology, 2018, vol. 309, p. 60–76

The sedimentary connection which may occur between the front of active rock glaciers and torrential channels is not well understood, despite its potential impact on the torrential activity characterizing the concerned catchments. In this study, DEMs of difference (DoDs) covering various time intervals between 2013 and 2016 were obtained from LiDAR-derived multitemporal DEMs for three rapidly...

Université de Fribourg

Erosion and sediment transfer processes at the front of rapidly moving rock glaciers: Systematic observations with automatic cameras in the western Swiss Alps

Kummert, Mario ; Delaloye, Reynald ; Braillard, Luc

In: Permafrost and Periglacial Processes, 2017, vol. 29, no. 1, p. 21–33

When connected to torrential channels, the fronts of active rock glaciers constitute important sediment sources for gravitational transfer processes. In this study, a 2013– 16 time series of in situ webcam images from the western Swiss Alps was analyzed to characterize the erosion processes responsible for sediment transfer at the front of three rapidly moving rock glaciers and their...

Université de Fribourg

Resolution capacity of geophysical monitoring regarding permafrost degradation induced by hydrological processes

Mewes, Benjamin ; Hilbich, Christin ; Delaloye, Reynald ; Hauck, Christian

In: The Cryosphere, 2017, vol. 11, no. 6, p. 2957–2974

Geophysical methods are often used to characterize and monitor the subsurface composition of permafrost. The resolution capacity of standard methods, i.e. electrical resistivity tomography and refraction seismic tomography, depends not only on static parameters such as measurement geometry, but also on the temporal variability in the contrast of the geophysical target variables (electrical...