The Swiss Permafrost Monitoring Network PERMOS celebrated 10 years of operation in 2010. PERMOS was initiated as a research-oriented network in the 1990ies, and officially started with a pilot phase in 2000. It is continuously developing towards an operational monitoring service. The joint funding by the Federal Office for the Environment (FOEN), the Swiss Academy for Sciences (SCNAT) and MeteoSwiss via the Swiss GCOS Office proved successful and substantially supports the network. In 2010, a renewal of the contract for the period 2011–2014 has been signed. The PERMOS Office (at the University of Zurich) coordinates observation and reporting activities, which are undertaken by six partner institutions (ETH Zurich, Universities of Berne, Fribourg, Lausanne and Zurich, WSL Institute for Snow and Avalanche Research SLF).

 


Excursion to the monitoring site at Gemsstock in the course of the 10th anniversary of PERMOS and view to Urseren Valley with the Tiefen glacier and granite rocks of the Central Swiss Alps in the background

PERMOS 2011 includes three types of observations: (1) ground temperatures measured at and below the surface at borehole sites, (2) changes in subsurface ice and water content at these sites inferred by geophysical surveys, and (3) velocities of permafrost creep determined by geodetic surveys and/or photogrammetry. In addition, standardized documentation of fast mass movements from permafrost areas (e.g., rock fall) is being established. The three observation elements complement each other, and strategies to deliver a comprehensive picture that cannot be achieved without their joint interpretation are being developed. The observation sites have been carefully evaluated at the end of 2009 based on site characteristics, instrumentation and data quality. As a result so-called PERMOS Reference Sites have been determined. These sites provide the full set of parameters and are considered suitable for long-term operation. In addition, a number of PERMOS Consolidation Sites complement the network.

In addition to the regular field work, collaboration and reporting, major efforts in 2010 and in 2011 were related to integration, processing and storage of the data and the standardization of site instrumentation and strategies. The recently established monitoring activities in neighbouring countries have led to increasing collaboration and exchange with other institutions involved in mountain permafrost research.

The WSL Institute for Snow and Avalanche Research SLF continues to monitor ground temperatures and slope deformation in a growing network of high altitude boreholes (M. Philipps). Seven of these sites are included in PERMOS. On the basis of this valuable data E. Zenklusen Mutter has submitted a dissertation entitled 'Statistical Analysis of Mountain Permafrost Temperatures'. In addition, terrestrial laserscanning is intensively used to investigate the dynamics of rockwalls, rock glaciers and scree slopes - in combination with airborne laserscanning and photogrammetry. The practical guideline 'Construction on permafrost' published in 2009 has been translated into French and Italian and is in widespread use in the Swiss Alps and neighbouring countries. A new German-Swiss project has just been started in collaboration with the University of Bonn to investigate the thermal and mechanical impacts of snow on frozen rockwalls. SLF is also a project partner in the recently launched Swiss Sinergia project 'The Evolution of Mountain Permafrost in Switzerland' (TEMPS). See www.slf.ch for further details.

 

 


Terrestrial laserscanner at Ritzlihorn (Bernese Alps), summer 2010, after a large debris flow damaged infrastructure in the underlying valley (Photo: M. Phillips).

The Institute of Geography of the University of Lausanne (C. Lambiel, C. Scapozza, J.-B. Bosson, L. Ravanel) leads several research projects on mountain permafrost. In 2011 ended the project ‘Distribution and structure of permafrost in alpine talus slopes’. The use of a multi-method approach (ground temperature monitoring, borehole logging, electrical resistivity tomography, seismic refraction, etc.) offered a precise imagery of the ground stratigraphy within the five talus slopes prospected in the study showing the very heterogeneous permafrost distribution and ice content at the slope scale.

In summer 2011, geophysical prospecting was carried out on a destabilized pebbly rock glacier made of calcareous schists, which is affected by severe slump processes and velocities of about 10 m/year (Tsaté-Moiry rock glacier, Valais Alps) revealing once again the extreme discontinuity of mountain permafrost. Attempts are currently made to integrate this discontinuity in a model with a machine learning approach in order to improve the accuracy of permafrost extension maps in mountain areas.

Researches at the University of Lausanne also concern the glacier-permafrost interactions. In 2011 a project was launched to study the internal structure as well as past and current evolution of small debris covered glacier and their associated glacier forefields, in which large quantities of ground ice can be found. Related to this, the evolution of the Gentianes ice-cored moraine is studied with terrestrial laser scanning since 2007. A new project launched in summer 2011 aims at studying the evolution of recently deglaciated rock walls and/or affected by permafrost conditions with TLS and rock temperatures measurements in the Mont Fort area (Verbier).

More generally, efforts are continuing in mountain permafrost monitoring on various sites of the Valais Alps. DGPS measurements are repeated annually on 8 rock glaciers, bi-annually on 6 of them and seasonally on 2 of them, in order to follow their velocity variations. Ground temperatures are recorded in 13 boreholes, whereas ground surface temperature monitoring is carried out on about 120 sites. 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.
Following a variety of seismic refraction, GPR and geoelectric campaigns, 7 boreholes have been located and drilled by the Institute for Geotechnical Engineering and the Institute of Geophysics ETH Zurich to depths ranging from 25 m to 28 m in the degrading Furggwanghorn rock glacier in the Turtmann valley (S. Springman, T. Buchli, H. Maurer). The hydrological regime has led to the development of thermokarst and depressions at the root, which are combining with surface deformations at more than 3 m/a. A multi-method deformation monitoring campaign utilizing terrestrial lidar, radar interferometery and DGPS is being conducted to determine surface movements and to combine these with data of shear at depth from borehole inclinometers. A meteorological station has been installed and thermistor chains have been placed in each borehole. Active layer investigations are being conducted by monitoring fluxes and further geophysical and hydrological campaigns are planned for next summer. A series of laboratory experiments are underway and combine with pressuremeter tests that were conducted in two of the boreholes to determine stress strain response in the rock glacier body. This characterisation will contribute parameters for the thermo-hydro-mechanical modelling phases to follow.

At the University of Zurich, Department of Geography, strategy and method for modelling permafrost distribution over entire mountain regions was developed and applied to the European Alps. A corresponding map showing permafrost distribution for the entire Alps with a resolution of approximately 30m is now available online. The legend and interpretation key communicate the uncertainties of the sparse data basis and the statistical modelling approach and allow to further refine the estimate shown on the map based field information (Böckli, Nötzli, Brenning, Gruber). A global permafrost map with a resolution of 1km has been elaborated and is also available online. It shows the importance of heterogeneity (such as topography or non-continuous permafrost) globally as well as the difficulties involved in validating or calibrating any global permafrost model (Gruber). Both maps are available online at www.geo.uzh.ch/microsite/cryodata/.

Based on 40 footprints that each contains ten iButton temperature loggers within 10m x 10m, mean annual ground surface temperature, the date of snow melt, and the date of snow-pack ripening have been calculated. The small-scale replication allowed to also investigate the often considerable variability that exists over short distances and that makes the comparison of grid-based models with point measurements difficult (Gubler,  Fiddes, Schmid, Gruber).
The wireless sensor networks on Matterhorn and Jungfraujoch allowed demonstrating that temperatures at depth in heterogeneous and fractured bedrock can be markedly lower than assumed based on measurements and models in near-vertical and homogeneous rock. Furthermore, the measurement of cleft-dilatation on Matterhorn allowed distinguishing two modes of movement for permafrost rock mass with ice-filled clefts. One type points to ordinary thermo-mechanical forcing whereas the other shows an effect of ice temperature or melt (Hasler, Beutel, Gruber).
Dedicated hardware for the low-power operation of inexpensive single-frequency GPS for continuously monitoring the movement of slopes has been developed. The devices either log raw data or transmit wirelessly. First test show daily GPS solutions in post-processing to result in a positional accuracy of about +/- 1mm and resolve short bursts of rock glacier movement during snow melt and precipitation. In total, about 20 locations have been equipped for continuous GPS monitoring (Wirz, Buchli, Limpach, Su, Beutel, Raetzo, Gruber).

Based on a pilot campaign, the feasibility and utility of outdoor acoustic emission sensing for monitoring rock damage during freezing has been demonstrated. Based on this, a measurement system for continuous operation in high-elevation rock walls has been developed, tested and installed. It contains the sensing and processing hardware, methods for fixing the sensors at depth, for installing temperature and liquid water probes in rock at depth, and for sealing boreholes appropriately. These measurements will provide a means to scale theoretical and laboratory insight on frost weathering and ice segregation to real conditions (Girard, Weber, Hunziker, Beutel, Amitrano, Gruber).
The measurements of rock and cleft temperature and dilatation as well as the continuous GPS and the acoustic emission monitoring are made in customized wireless sensor networks. This technology has moved from an experimental to an operational phase with continuous and highly reliable measurements. For the computer engineering community, this resulted in a new focus on the investigation of data quality issues, post-processing and online data cleaning mechanisms (Buchli, Keller, Lim, Beutel).

The open-source model GEOtop has been further tested and consolidated for simulating the coupled heat and water transfer in frozen soil and rock in mountain topography. The introduction of scripting interface now allows to conduct large parameter studies with high-performance computing (Endrizzi, Gruber). In order to apply such simulations to large mountain ranges, a method for sub-grid computation based on a lumped model is in development (Fiddes, Gruber).  

During 2010, the University of Zurich (I. Gärtner-Roer) also quantified rockglacier kinematics by in situ measurements (tachymeter) at several PERMOS sites (Murtèl (keysite), Muragl,  Turtmann Valley (keysite)) . Additional rockglaciers were surveyed within the project "Monitoring and process analysis of permafrost creep and failure in changing temperature regimes", which is part of the German DFG-bundel "Sensitivity of Mountain Permafrost of Climate Change (SPCC)" running 2008-2011.  An additional series was started on the destabilized Furggwang rockglacier, which is intensely investigated (7 boreholes with temperature and inclinometer measurements, geophysics, hydrology) by the ETHZ (S. Springman). In 2011 the kinematic measurements continue on the PERMOS and project sites mentioned already in 2010. In addition, data compilation with the “Airborne Digital Sensor” (ADS, Leica Geosystems) was started within PERMOS and will be evaluated within the SNF project TEMPS. Together with Norwegian colleagues (B. Etzelmüller, K.Lilleoeren, A. Kääb; University of Oslo) a rockglacier study was performed on Iceland by combining field mapping and analysis of aerial images and PALSAR data.

2011 started the SNF (Swiss National Foundation) Sinergia project TEMPS “The Evolution of Mountain Permafrost in Switzerland” whose lead is located at the University of Fribourg (C. Hauck). The 3-year project regroups researchers from the Universities of Lausanne, Fribourg and Zurich, the ETH Zurich and the WSL Institute for Snow and Avalanche Research SLF and consists of 4 strongly collaborating and inter-related subprojects, which focus specifically on the determination of the current state, and on the dominant processes influencing the future evolution of permafrost in the Swiss Alps, namely TEMPS-A “Regional Climate Model analysis for Alpine permafrost research” (Schär, Kotlarski, Salzmann, Rajczak), TEMPS-B “Ground ice and water content estimation and integrative analysis of mountain permafrost monitoring elements (Delaloye, Hilbich, Lambiel, Noetzli, Staub), TEMPS-C “From kinematics to dynamics: geomorphic and physical controls of permafrost creep derived from airborne digital sensors and terrestrial surveys” (Gärtner-Roer, Phillips, Schaepman) and TEMPS-D “Subsurface modelling of the sensitivity of mountain permafrost to climatic changes (Hauck, Hoelzle, Marmy). Based on process and modelling studies, the project seeks to understand the permafrost system in general and in an integrative way, and on different spatial and temporal scales.
In 2010 and 2011 has continued the GRAPE ”Ground-Atmosphere Modelling of Permafrost Evolution” subproject (Hauck, Hoelzle, Salzmann, Schneider, Scherler, Pellet, Rosset), part of the project cluster “Sensitivity of Mountain Permafrost to Climate Change” (SPCC). GRAPE has aimed on the one hand at bridging the gap between the analysis of global causes (RCM modelling) to the analysis of local impacts (mountain permafrost degradation) involving the scale transfer from RCM simulations (ENSEMBLES) to the quantification of freeze and thaw processes within the subsurface, and on the other hand at combining the refined model tools to include (a) atmospheric drivers, (b) improved assessment of current ground ice characteristics, (c) improved process analysis concerning permafrost degradation and aggradation and (d) analysis of possible future impact scenarios based on validated model simulations using geophysical, meteorological and borehole temperature monitoring data.

2011 saw also the finalization of the PhD thesis of S. Morard dedicated to the analysis of the effect and the efficiency of the air circulation for cooling deepest layer of a porous debris accumulation (talus slopes, relict rock glaciers) and also for preserving and/or generating an extrazonal permafrost at locations where the MAAT is largely above freezing conditions (>4°C). In addition the climate, ventilation and ice formation of the Diablotins ice cave has been investigated for the last two years (Morard, Bochud, Delaloye). Whereas the cave was almost not frozen around 1990, the ice has aggraded since that time and still prevents nowadays the continuation of the exploration in one of the deepest karstic cave system in the area.

 

 


The Diablotins ice cave in the Swiss Prealps : subliming ice stalactites by aspiration of cold air inside the cave in winter time (top); ice flooding (bottom) (photos: R. Delaloye)

The creep rate of Alpine rock glaciers and periglacial mountain slopes has continued to be surveyed by DGPS as well as by satellite SAR interferometry at the University of Fribourg (Barboux, Delaloye). A particular emphasis has been put for the last years on surveying rapidly moving, sometimes completely destabilized rock glaciers in the Valais Alps (western Switzerland) as for instance the Grabengufer rock glacier, which moved up to 180 m between 2009 and 2011.

 

 


The unstable front of the destabilized Grabengufer rock glacier in winter 2010 (photo: R. Delaloye)

Reynald Delaloye (reynald.delaloye@unifr.ch)