Influence of different digital terrain models (DTMs)on alpine permafrost modeling

The thawing of alpine permafrost due to changes in atmospheric conditions can have a severe impact, e.g., on the stability of rock walls. The energy balance model, PERMEBAL, was developed in order to simulate the changes and distribution of ground surface temperature (GST) in complex high-mountain topography. In such environments, the occurrence of permafrost depends greatly on the topography, and thus, the digital terrain model (DTM) is an important input of PERMEBAL. This study investigates the influence of the DTM on the modeling of the GST. For this purpose, PERMEBAL was run with six different DTMs. Five of the six DTMs are based on the same base data, but were generated using different interpolators. To ensure that only the topographic effect on the GST is calculated, the snow module was turned off and uniform conditions were assumed for the whole test area. The analyses showed that the majority of the deviations between the different model outputs related to a reference DTM had only small differences of up to 1 K, and only a few pixels deviated more than 1 K. However, we also observed that the use of different interpolators for the generation of a DTM can result in large deviations of the model output. These deviations were mainly found at topographically complex locations such as ridges and foot of slopes

Rockglaciers of the Engadine

The Engadine is one of the rockglacier hot spots in the European Alps. Many rockglaciers in all states of activity (active, inactive, relict) are found, indicating the former and present occurrence of permafrost. This is due to continental climate conditions, high elevation, and high weathering rates. Rockglaciers are developed in valley bottoms, such as the Val Sassa and the Val da l’Acqua rockglacier, or in formerly glaciated cirques, such as the Muragl or the Murtèl rockglacier. Hence, the Engadine is the home of research on rockglaciers in Europe with the first studies on rockglaciers of the Swiss National Park one century ago. Engadine was also the first place in the world where boreholes in rockglaciers were drilled in 1987. Nowadays, several Engadine rockglaciers are monitored within the Permafrost Monitoring Network Switzerland (PERMOS)