Miniature temperature dataloggers for mapping and monitoring of permafrost in high mountain areas: rst experiences from the Swiss Alps. Permafrost and Periglacia l Processes

Measurements of bottom temperatures of the winter snow cover (BTS) constitute a well-established method to map permafrost distribution in mountain areas. A method for continuous measurements of BTS with miniature dataloggers (MTDs) is used with a newly developed logger. This new tool is specially designed for rough field conditions. It was tested in two case studies on and around rock glaciers in Switzerland. One test site was in the Murtèl-Corvatsch area (Upper Engadin) and the other in the Furggentälti area (Bernese Alps). The basic assumptions of the conventional BTS method were verified with continuous measurements. Important boundary conditions for BTS measurements are a suciently thick, undisturbed snow cover and an ade-quate measurement time. In autumn, before the snow cover is well developed, air circulation is still possible within the coarse active layer of rock glaciers, and heat exchange through the thin snow cover is facilitated. At the end of winter, meltwater percolation disturbs the equilibrium BTS. At the base of an artificially compacted snow cover, temperatures were influenced by atmospheric variations throughout the whole winter. Use of the new loggers is suggested as suitable for mapping and monitoring the distribution and long-term development of mountain permafrost. Process understanding in the active layer of coarse debris material, on the other hand, need