Distinguishing ice-rich and ice-poor permafrost to map ground temperatures and -ice content in the Swiss Alps

Abstract

<p><strong>Abstract.</strong> A new countrywide permafrost distribution map of Switzerland is presented, indicating ground temperatures and ice content. The new representation of ground temperatures is achieved by distinguishing ice-poor and ice-rich permafrost in the modelling process. There is a very significant correlation of ground temperatures with elevation and potential incoming solar radiation in ice-poor and ice-free ground. The distribution of ice-rich permafrost was defined by modelling mass wasting processes and the integration of snow and ice into the ground caused by them. This dual approach allowed a clear improvement in the cartographic representation of permafrost-free elevational belts which are bordered above and below by permafrost. The reproduction of such commonly occurring permafrost gaps allowed a higher mapping accuracy and unambiguity of the mapping zones. Permafrost occurrence is represented by two clearly defined classes: Zone 1 representing modelled ground temperatures and zone 2 indicating excess ground ice outside of zone 1. 58 % of 92 validation sites could be definitively classified as having permafrost or no permafrost. If only ice-poor or –free ground is considered, this value reaches 90 %. The rather simple dependency of ice-poor permafrost on two main parameters is not only relevant for mapping but also for a wide range of scientific and engineering purposes.</p>