Assessment of thermal stabilization measures based on numerical simulations at a Swiss alpine permafrost site

Abstract. Global warming causes thawing of permafrost, leading to landscape changes and infrastructure damage, problems that have intensified worldwide in all permafrost regions. This study numerically investigates the impact of different thermal stabilization methods on preventing or delaying permafrost thawing. To test different technical methods, an alpine mountain permafrost site with nearby infrastructure is investigated. Model simulations represent the one-dimensional (1D) effect of heat fluxes across the complex system of snow–ice–permafrost layers and the impact of passive and active cooling, including engineered energy flux dynamics at the surface. The results show the efficiency of different passive, active and combined thermal stabilization methods in influencing heat transfer, temperature distribution, and the seasonal active-layer thickness (ALT). Investigating each component of thermal stabilization helps quantify the efficiency of each method and determine their optimal combination. Despite providing efficient cooling in winter, passive methods are less efficient, as the ALT remains over 1 m. Conductive heat flux attenuation alone takes several years to form a stable frozen layer. Active cooling, when powered by solar energy, decreases the ALT to only a few decimetres. The combination of active and passive cooling, together with conductive heat flux attenuation, performs best and allows excess energy to be fed into the local grid. The findings of this study show the evolution of ground temperature and permafrost at a representative alpine site under natural and thermally stabilized conditions, contributing to understanding the potential and limitations of stabilization systems and formulating recommendations for optimal application.