Swiss Permafrost Monitoring
The Swiss Permafrost Monitoring initiative PERMOS (http://www.permos.ch) maintains a network of 28 high alpine sites in order to document the state and changes of permafrost in Switzerland based on three main observation elements (ground temperatures, changes in subsurface ice and water content, and permafrost creep velocities). PERMOS is funded by the Federal Office for the Environment (FOEN), the Swiss GCOS Office at MeteoSwiss, and the Swiss Academy of Sciences (SCNAT). The PERMOS Office (at the University of Zurich) coordinates observation and reporting activities undertaken by the six partner institutions ETH Zurich (ETHZ), the Universities of Fribourg (UNIFR), Lausanne (UNIL), Zurich (UZH), the WSL Institute for Snow and Avalanche Research (SLF) and the University of Applied Sciences and Arts of Southern Switzerland (SUPSI, since 2013).
In addition to the regular field work, collaboration and reporting, major efforts in 2012 and in 2013 were related to the integration, processing and standardisation of the observational data and the build-up of a relational data base that provides raw data as well as products (various deduced parameters, indexes, processing repositories, web access, DOI registration etc.). This work was done in close collaboration with the research project TEMPS (see below) in order to organise and provide the PERMOS data set for comprehensive analyses across sites and parameters. Coordination with the Alpine Permafrost Database and the GTN-P database are ongoing. Further, the 5th two-year report on «Permafrost in Switzerland 2008/2009 and 2009/2010» was published in late 2013, which completes the reporting on the first 10 years of official PERMOS operation since 2000.
Ongoing research projects and activities
Closely related with PERMOS is the SNSF-Sinergia project «The evolution of Mountain Permafrost in Switzerland» (TEMPS, 2011-2014), consisting of more than 15 scientists from 5 Swiss research institutions (ETH Zurich, Universities of Fribourg, Lausanne, and Zurich, WSL Institute for Snow and Avalanche Research SLF). One particular aim of this project is to combine observation and model-based research approaches and to obtain an integrative view about the current state and the governing processes for recent and future mountain permafrost evolution. In addition, complementary data (mostly geophysical measurements) are acquired for the most important PERMOS monitoring sites which are necessary to quantify the ground ice and water content (Fig. 1). At two sites in the Valais Alps, automated ERT devices are being installed with the aim to analyse the freezing and thawing of the active layer and the penetration of the melt water in early summer with 2D electrical profiles at very high temporal resolution.
Figure 1. ERT measurements at the Schafberg rock glacier in August 2013 (Photo: B. Staub).
The work done in 2013 focused on methodological improvements of the various modelling and observation techniques, which are a necessary precondition for the synergetic data analysis, scenario generation and impact assessment of the TEMPS project. During the final year of the project, all approaches will serve jointly to link climate change data to past and future temperature and ground ice content changes and slope movements of mountain permafrost occurrences in Switzerland. In addition, two workshops and scientific meetings were organised and helped to promote the TEMPS project to a broader public. A final symposium including decision makers will take place in January 2015.
Within the project X-Sense (UZH, ETHZ, FOEN, GAMMA) 18 permanent GPS stations have been installed in 2011 in the Valais Alps to monitor slope movements of diverse landforms. Distributed near-surface ground temperature measurements, a weather station and a high resolution camera on the opposite slope provide additional information on environmental factors. The continuous high resolution (daily) data over a period of more than two years allow for studying the short-term variability of diverse slope movements (joint-project between UZH and ETH of Zurich, Wirz, Beutel, Gruber, Limpach, Purves). Two acoustic emission (AE) measurement assemblies were installed in steep alpine rock-walls in 2011 as a pre-study of a follow up project. The combination of the captured AE activity, used as a proxy of rock damage, with the rock temperature/moisture content shows that (1) liquid water content has an important impact on freezing-induced rock damage, (2) sustained freezing can yield much stronger damage than repeated freeze-thaw cycling, and (3) that frost cracking occurs over the full range of temperatures measured extending from 0 down to –15°C (Girard, Gruber, Weber, Beutel). The project X-Sense2 (UZH & ETHZ) started in November 2012 with the aim to develop and apply ultra-low-power monitoring systems for early detection of failure processes in unstable rock masses and periglacial slope movements. The project will exploit advances in MEMS technology to achieve a trigger-based duty-cycling of complex sensing systems by monitoring micro-seismic (Vieli, Faillettaz, Weber, Beutel).
The ongoing project on Alpine solifluction at the Institute of Geography at the University of Bern (GIUB, Rist & Veit) investigates the spatial and temporal dynamics of alpine solifluction and their environmental controls in seasonal frost and permafrost. The main study site is situated on the north slope of Blauberg close to Furkapass and ranges from 2380 m – 2700 m a.s.l. (Fig. 2).
Figure 2. Terrestrial geodetic survey of solifluction lobes on the north slope of Blauberg, Furka (Photo: A. Rist).
New in PERMOS is the Institute of Earth Sciences of the University of Applied Sciences and Arts of Southern Switzerland (SUPSI) with the new research group on alpine periglacial geomorphology under the coordination of Dr. Cristian Scapozza. This group is active in thermal and kinematic monitoring of active rock glaciers, 2D and 3D photogrammetrical analysis and studies focusing on the link between permafrost and mass movements.
Permafrost research activities at the University of Zurich (UZH) continue after Prof. A. Vieli has taken over the head of the group in 2013 and focus on measuring, monitoring and modeling of permafrost in Alpine terrain. UZH is actively involved in the above described PERMOS (Office hosting institution, Noetzli, Gaertner-Roer, Gruber, Hilbich, Voelksch) and the subprojects TEMPS-B (Hilbich, Noetzli, Voelksch) and TEMPS-C (Gaertner-Roer, Mueller, Schaepmann).
S. Gubler, J. Fiddes and L. Boeckli completed their PhD theses at UZH. Gubler studied the measurement variability and related model uncertainty in mountain permafrost research. An extensive small-scale study on the variablity of thermal ground surface conditions allowed to investigate the considerable variability that exists over very short distances and that makes the comparison of grid-based models with point measurements difficult. This variability indicates that physically-based mountain permafrost models should be evaluated at locations representing different environmental factors that influence permafrost occurrence. Further, several short- and longwave downward radiation parameterizations were evaluated to increase the accuracy of modeled radiative fluxes in impact models (Gubler, Gruber, Purves).
Boeckli developed strategies and methods to characterise permafrost over entire mountain regions and applied it to the European Alps. This includes a modeling approach map to provide the first fully consistent permafrost distribution map for the European Alps as well as an estimation of the total permafrost ice content in the Alps as a first step towards the understanding of permafrost hydrology in a changing climate. (Böckli, Nötzli, Brenning, Gruber). The map is available at www.geo.uzh.ch/microsite/cryodata/.
Fiddes designed two new tools to aid numerical physically-based modelling in complex and remote terrain (Fiddes, Gruber). The first tool (TopoSUB) is an efficient subgrid scheme that uses statistical methods to reduce the computational burden of large area simulations by several orders of magnitude. It works with a 1-D model and parameterises important 2-D effects. The second tool (TopoSCALE) comprises a suite of methods to downscale gridded data products from atmospheric models (e.g. ERA-Interim) in order to derive the required meteorological forcing for the numerical model. It makes use of 3-D fields on atmospheric model pressure levels and also accounts for high resolution terrain effects (e.g. solar geometry). Both tools have been evaluated independently and the scheme has been successfully applied to simulate permafrost over the entire Swiss Alps
The permafrost group of the Institute of geography and sustainability of the University of Lausanne (C. Lambiel, J.-B. Bosson, N. Deluigi) leads several research projects on mountain permafrost: One of their main activities focuses on ground ice detection, mapping and characterization. Especially large efforts are currently concentrating on glacier forefields of small high elevation glaciers, which extended during the Little Ice Age inside the periglacial belt. Many of these glaciers are dominated by high rock walls that have produced large amounts of sediments all along the Holocene. Remobilization of the sediments by the glaciers has led to the formation of thick moraine complexes, as for instance morainic dams. Another consequence is the burying of large amounts of ice during the last century.
The PhD Thesis of J.-B. Bosson, carried out in the Mont Blanc massif, the Arolla valley and the Diablerets massif, aims at 1) determining the ice content (both glacier and permafrost ice) within these complexes and 2) quantifying the past and current evolution of the debris-covered glaciers, especially the melt rate of ground ice. Electrical resistivity tomography, ground surface temperature measurements, coupled with digital photogrammetry, dGPS measurements, terrestrial laser scanning and the use of webcams are the main methods used in these studies.
Another topic is the study of slope movements within the periglacial belt. A study of the historical development of ice-supersaturated sediments with digital photogrammetry has recently started. Quantification of movements and deformation process understanding of rock glaciers and other ground ice related landforms are made using DGPS, Terrestrial Laser Scanning (Lidar), permanent GPS and webcams.
Modelling the high discontinuity of mountain permafrost is a challenging task. In order to reproduce the spatial heterogeneity of the phenomenon at the local scale, Machine Learning algorithms have been tested to propose a new approach for mountain permafrost modelling. The basic concept of Machine Learning is that the machine learns from the data (i.e., for permafrost modeling, rock glacier inventories and sectors of known permafrost thanks to geophysical or borehole data). First results show that, if the dataset is large enough, the high spatial discontinuity of mountain permafrost can be successfully represented. For instance, rock glaciers can be automatically recognized and, in some cases, permafrost is designed only in the lower part of talus slopes, which corresponds to several field data.
In the framework of permafrost characterizing and monitoring, a new borehole was drilled in the ice-cored moraine at Col des Gentianes (Verbier) during summer 2012 (Fig. 3). More generally, efforts in mountain permafrost monitoring on various sites of the Valais Alps were continued. The movements of about 10 rock glaciers are measured between 1 and 2 times/year by DGPS. Ground temperatures are recorded in 13 boreholes, whereas ground surface temperature monitoring is carried out on about 120 locations. First measurements began in 1998. Finally, electrical resistivity monitoring is led on 2 sites since 2007. A part of these measurements are included in the PERMOS network.
Figure 3. Drilling of a borehole in an ice-cored moraine at Col des Gentianes (Verbier, 2900 m a.s.l., Photo: C: Lambiel).
In parallel to its long-term monitoring of borehole temperatures and deformation together with PERMOS, the WSL Institute for Snow and Avalanche Research (SLF) is investigating the impact of the snow cover on the thermal regime and stability of steep rockwalls (A. Haberkorn, M. Phillips) in the context of an SNF project and in collaboration with the University of Bonn / TU Munich (D. Draebing, M. Krautblatter) at three sites in the Swiss Alps. Rockwall dynamics are also being monitored using various remote sensing techniques including terrestrial laserscanning and interferometric radar at Pizzo Cengalo (Bregaglia), in collaboration with different Swiss and Italian partners in the context of an ARGE Alp project (F. Amann, Y. Bonanomi, A. Huwiler, R. Kenner, A. Kos, R. Lüthi, V. Mair, M. Phillips). The stability and thermal regime of high mountain infrastructure such as cable cars, avalanche defence structures and buildings are monitored (M. Phillips) with various engineers and operators. The dynamics of rock glaciers are being investigated in the context of the SNF Sinergia project TEMPS and in collaboration with Italian partners in the Interreg project SloMove (R. Kenner) using in-situ and remote sensing techniques. Mountain permafrost ice from SLF study sites is currently being analysed for microorganisms in the context of an internal WSL project (B. Frey).
At the University of Fribourg, the SNSF-Project Soil moisture in mountainous terrain and its influence on the thermal regime in seasonal and permanently frozen terrain (SOMOMOUNT) started in 2013 with the setup of a soil moisture monitoring network at middle and high altitudes in the Swiss Alps. In a second step, those data sets will be used to investigate the influence of temporally and spatially changing soil moisture on the thermal regime of seasonal and permanently frozen ground. The SOMOMOUNT project is directly linked with TEMPS and PERMOS (see above).
In addition to the already mentioned projects, the University of Fribourg has currently a large research group (Hauck, Hoelzle, Delaloye, Salzmann, Hilbich, Hasler, Scherler, Schneider, Barboux, Mari, Marmy, Staub, Kummert) focussing on a wide range of topics between the analysis of rock mechanics and rock glacier dynamics, sediment transport, geomorphology, geophysics, subsurface modelling and remote sensing related with permafrost. Furthermore Martin Scherler finished his PhD on the topic “Sensitivity of Mountain Permafrost to Climate Change Scenarios: A Modelling Approach” in 2013. S Schneider (The heterogeneity of mountain permafrost: A field-based analysis of different periglacial materials) and S Mari (Tracing experiments in active rock glaciers) are finishing their PhD thesis.
Figure 4. Rockfall from Pizzo Cengalo on 24.9.2013 (Photo: D. Fuchs).
Figure 5. Interferometric radar measurements by A. Kos at Pizzo Cengalo on 13.9.2013 (Photo: M. Phillips).
Report prepared by Reynald Delaloye (firstname.lastname@example.org).