Modelling of frozen ground

Frozen ground, including permafrost (permanently frozen ground), is an important thermal phenomenon in mountainous and polar regions of the world.

In addition to the monitoring of physical variables in the frozen subsurface  (permafrost monitoring à link to research cluster 1), our research group develops and applies physically-based models to simulate the relevant thermal and hydrological processes in the subsurface, with a focus on soil freezing and thawing.

These include complex hydro-thermal soil models, energy balance models, but also coupled geophysical-thermal model approaches using geophysical data (see also research cluster 6 à link).

 

TEMPS (The evolution of mountain permafrost in Switzerland)

 

Permafrost, defined as lithospheric material whose temperature remains below 0 °C for two or more consecutive years, occurs in many high-mountain regions of the European Alps. In the context of anticipated climatic changes, permafrost degradation and associated ground deformation and instabilities could occur. To evaluate the sensitivity of mountain permafrost to climatic changes and to assess its future evolution, not only climatic variables such as air temperature, radiation and timing and duration of snow cover have to be considered, but also subsurface characteristics such as ground temperature, ice content, porosity or hydraulic properties.

Permafrost monitoring in the Swiss Alps started only 1-2 decades ago, but currently comprises a large set of meteorological, geophysical, kinematic and ground thermal parameters at a large variety of field sites, e.g. within the national permafrost monitoring network PERMOS. The project TEMPS analysed and integrated these high-mountain observations with model simulations using a dynamic process-oriented permafrost model. In combination with results from Regional Climate Model simulations, TEMPS created plausible evolution scenarios of mountain permafrost at specific sites and investigated the interactions between atmosphere and permafrost focusing on the evolution of ground temperature, ice content and related degradation and creep processes.

The overall objective of the SNF-Sinergia project TEMPS is to improve the understanding of the vulnerability of mountain permafrost regions to climate changes and assess the potential impact at different field sites in the Swiss Alps. The project includes collaborating scientists from a variety of different fields, such as atmospheric and cryospheric sciences, geomorphology, geophysics, geography and remote sensing.

 

Webpage:  http://p3.snf.ch/project-136279 ; www.temps-symposium.ch

 

Duration: 2011-2015

 

Funded by: Swiss National Science Foundation (SNF)

 

Project lead: Prof. Christian Hauck

 

Partner(s): Universities of Fribourg, Lausanne and Zurich, ETH Zurich, WSL Institute for Snow and Avalanche Research SLF

 

Collaborators: R. Delaloye, A. Hasler, M. Hoelzle, C. Hilbich, A. Marmy, N. Salzmann, B. Staub, (Univ. Fribourg), I. Gärtner-Roer, J. Müller, J. Noetzli, M. Schaepman, I. Völksch (Univ. Zurich),  S. Kotlarski, J. Rajczak, C. Schär (IAC, ETH Zurich), C. Lambiel (Univ. Lausanne), R. Kenner, R. Lüthi, M. Phillips  (WSL Institute for Snow and Avalanche Research SLF, Davos)

 

Contact at University of Fribourg: christian.hauck[at]unifr.ch

 

Publications at Univ. Fribourg (for complete list see also http://p3.snf.ch/project-136279):

Hauck, C. (2013): New concepts in geophysical surveying and data interpretation for permafrost terrain. Permafrost and Periglac. Process. 24, 131–137, doi: 10.1002/ppp.1774.

Kenner R., Bühler Y., Delaloye R., Ginzler C., Phillips M. (2013). Monitoring of high alpine mass movements combining laser scanning with digital airborne photogrammetry. Geomorphology. 10/2013; DOI: 10.1016/j.geomorph.2013.10.020

Marmy A, Salzmann N, Scherler M, Hauck C (2013): Permafrost model sensitivity to seasonal climatic changes and extreme events in mountainous regions, Environ. Res. Lett. 8 035048 doi:10.1088/1748-9326/8/3/035048

Marmy, A., Rajczak, J., Delaloye, R., Hilbich, C., Hoelzle, M., Kotlarski, S., Lambiel, C., Noetzli, J., Phillips, M., Salzmann, N., Staub, B., and Hauck, C. (2015): Semi-automated calibration method for modelling of mountain permafrost evolution in Switzerland, The Cryosphere Discuss., 9, 4787-4843, doi:10.5194/tcd-9-4787-2015.

Rajczak, J., Kotlarski, S., Salzmann, N., Schär, C. 2015: Robust climate scenarios for sites with sparse observations: a two-step bias correction approach. Int. J. Climatology. doi: 10.1002/joc.4417.

Scherler, M., Schneider, S., Hoelzle, M. and Hauck, C. 2014. A two-sided approach to estimate heat transfer processes within the active layer of the Murtèl–Corvatsch rock glacier. Earth Surf. Dynam., 2, 141–154.

Staub, B. & Delaloye, R. (in press): Using Near-Surface Ground Temperature Data to Derive Snow Insulation and Melt Indices for Mountain Permafrost Applications. Permafrost and Periglacial Processes.

Staub, B., Marmy, A., Hauck, C., Hilbich, C., and Delaloye, R. (2015): Ground temperature variations in a talus slope influenced by permafrost: a comparison of field observations and model simulations, Geogr. Helv., 70, 45-62, doi:10.5194/gh-70-45-2015.

Research aims/sciences questions:

This project aims at:

(1) Determine the influence of the material composition (air, ice and liquid water content, porosity) on ther-mal and kinematic processes and phenomena (e.g. conduction, advection, convection, phase changes, creep, deformation, instability)

(2) Identify the relative importance of site-specific, landform-specific and regional responses to climate forcing

(3) Analyse the future evolution of permafrost in the Swiss Alps.

Subprojects/methods: 

Study area: 
 


Exemplary results: 
 

Figure 1 : Site-scale climate scenarios of mean annual air temperature at 2 m above ground (MAAT) for six permafrost monitoring sites. The results are based on the developed scenarios using the two-step procedure of Rajczyk et al. (2015) and are based on 14 ENSEMBLES regional climate models assuming an A1B greenhouse gas emission scenario (taken from Marmy et al. 2015). 

Figure 2 : Difference in simulated (with the soil model COUP) mean annual soil temperature at 5m depth at the end of the century between a seasonal anomaly rum (i.e. the application of a ?Temperature and a ?Precipitation during a given season: DJF, MAM, JJA and SON, for every year) compared to a reference run for the permafrost site Schilthorn. The bars indicate the range of 10 individual GCM/RCM model chains for A1B scenario for the period 2020-2049 (blue) and for the period 2070-2099 (black) (taken from Marmy et al. 2013).

 


MODAIRCAP

Modelling of air circulation and energy fluxes in the coarse debris layer of high Alpine permafrost sites (MODAIRCAP)

Summary

Mountain permafrost is currently undergoing substantial changes due to climate change as a whole and especially due to the observed and projected air temperature increase. Among the typical mountain permafrost substrates, i.e. rock, fine sediments and coarse blocky surfaces, the latter play an important role because of their high insulating characteristics for the subsurface underneath due to the low thermal conductivity of the air voids between the blocks. In addition, air convection with upward transport of warmer air from the permafrost body and downward transport of cold air from the surface can take place within the coarse blocky layer, both, vertically (in flat terrain) as well as in form of a 2-dimensional slope circulation. These two effects lead to (i) low altitude permafrost occurrences in form of undercooled scree/talus slopes (e.g. Kneisel et al. 2000, Delaloye and Lambiel 2005), (ii) persisting permafrost occurrences at the lower limit of permafrost (in form of rock glaciers, ice-cored moraines and talus slopes) and (iii) much colder surface and subsurface temperatures for surfaces with coarse blocky surface layers (e.g., Schneider et al. 2012, Gubler et al. 2011, Gruber & Hoelzle 2008).

In this project we will use and adapt the modelling concepts from civil engineering (eg., Arenson et al. 2006, Goering & Kumar 1996) to model heat transfer in air flow in talus slopes and rock glaciers, and quantify the cooling effect in comparison with the other terms of the energy balance determined by existing energy balance approaches (e.g., Scherler et al. 2014).

Webpage: http://p3.snf.ch/project-169499

Duration: 2017-2020

Funded by: Swiss National Science Foundation (SNF)

Project lead/principal investigator (PI): Christian Hauck (Prof.)

Collaborators: Jonas Wicky (PhD student)

External collaboration with

  • PERMOS network

Contact at University of Fribourg: jonas.wicky[at]unifr.ch, christian.hauck[at]unifr.ch

Publications

Wicky, J. and Hauck, C. (2017). Numerical modelling of convective heat transport by air flow in permafrost talus slopes, The Cryosphere, 11, 1311-1325, https://doi.org/10.5194/tc-11-1311-2017.

Research aims/sciences questions

This project aims at:

1) Adapt existing engineering software that has already been tested for permafrost applications for real field cases in the Swiss Alps to enhance the process understanding

2) Quantify the amount of cooling due to convective air circulation within the coarse blocky layer to assess (i) the influence on the ground thermal regime, (ii) the importance on the energy balance and (iii) the development under climate warming.  

3) Validate the simulation results by ground surface temperature and borehole temperature data from the PERMOS network

Exemplary

 

Figure 1: Simulated temperature distribution (colours) and air current vectors in a talus slope for an open-to-atmosphere boundary for day 300 (winter circulation). The intensity of the circulation is marked by the grey/black colour of the vector arrows and is given in m day-1.

 

 

Figure 2:  Mean monthly air flow in a talus slope for an open-to-atmosphere boundary over 13 modelled years. The dashed line marks the domain of the talus slope. The seasonal differences in intensity and direction of the air circulation are clearly shown by the direction and colour of the arrows.

 

References

Arenson LU, Sego DC and Newman G (2006) The use of a convective heat flow model in road designs for Northern regions. 2006 IEEE EIC Climate Change Technology. 1–8 (doi:10.1109/EICCCC.2006.277276)

Delaloye R and Lambiel C (2005) Evidence of winter ascending air circulation throughout talus slopes and rock glaciers situated in the lower belt of alpine discontinuous permafrost (Swiss Alps). Norsk Geografisk Tidsskrift - Norwegian Journal of Geography 59(2), 194–203 (doi:10.1080/00291950510020673)

Goering DJ and Kumar P (1996) Winter-time convection in open-graded embankments. Cold Regions Science and Technology 24(1), 57–74 (doi:10.1016/0165-232X(95)00011-Y)

Gruber S and Hoelzle M (2008) The cooling effect of coarse blocks revisited: a modeling study of a purely conductive mechanism. 9th International Conference on Permafrost.

Gubler S, Fiddes J, Keller M and Gruber S (2011) Scale-dependent measurement and analysis of ground surface temperature variability in alpine terrain. The Cryosphere 5(2), 431–443 (doi:10.5194/tc-5-431-2011)

Kneisel C, Hauck C and Vonder Mühll D (2000) Permafrost below the Timberline Confirmed and Characterized by Geoelectrical Resistivity Measurements, Bever Valley, Eastern Swiss Alps. Permafrost Periglac. Process. 11(4), 295–304 (doi:10.1002/1099-1530(200012)11:4<295::AID-PPP353>3.0.CO;2-L)

Scherler M, Schneider S, Hoelzle M and Hauck C (2014) A two-sided approach to estimate heat transfer processes within the active layer of the Murtèl–Corvatsch rock glacier. Earth Surface Dynamics 2(1), 141–154 (doi:10.5194/esurf-2-141-2014)

Schneider S, Hoelzle M and Hauck C (2012) Influence of surface and subsurface heterogeneity on observed borehole temperatures at a mountain permafrost site in the Upper Engadine, Swiss Alps. The Cryosphere 6(2), 517–531 (doi:10.5194/tc-6-517-2012)

SOMOMOUNT (Soil moisture monitoring in mountain areas)

Improvement of geophysical monitoring routines for permafrost research

Unit of Geography - Chemin du Musée 4 - 1700 Fribourg - Tel +41 26 / 300 90 10 - Fax +41 26 / 300 9746
nicole.equey [at] unifr.ch - Swiss University