Miniature temperature dataloggers for mapping and monitoring of permafrostin high mountain areas: First experience from the Swiss Alps

Measurements of bottom temperatures of the winter snow cover (BTS) constitu te a well-established method to map permafrost distribution in mountain are as. A method for continuous measurements of BTS with miniature dataloggers (MTDs) is used with a newly developed logger. This new tool is specially de signed for rough field conditions. It was tested in two case studies on and around rock glaciers in Switzerland. One test site was in the Murtel-Corva tsch area (Upper Engadin) and the other in the Furggentalti area (Bernese A lps). The basic assumptions of the conventional BTS method were verified wi th continuous measurements. Important boundary conditions for BTS measureme nts are a sufficiently thick, undisturbed snow cover and an adequate measur ement time. In autumn, before the snow cover is well developed, air circula tion 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 wi nter, meltwater percolation disturbs the equilibrium BTS. At the base of an artificially compacted snow cover, temperatures were influenced by atmosph eric variations throughout the whole winter. Use of the new loggers is sugg ested as suitable for mapping and monitoring the distribution and long-term development of mountain permafrost. Process understanding in the active la yer of coarse debris material, on the other hand, needs further investigati on. Copyright (C) 1999 John Wiley & Sons, Ltd.