ACINN Graduate Seminar - SS 2025

2025-05-21 at 12:00 (on-line and on-site)

Surface and subsurface energy balance modelling on coarse-debris permafrost terrain: insights from in-situ measurements on Murtèl rock glacier (Swiss Alps)

Dominik Amschwand

Networked Embedded Sensing Group, Department of Computer Science, University of Innsbruck, Austria

 

The widespread degradation of mountain permafrost—perennially frozen ground inhigh-alpine environments—is largely driven by rising air temperatures that alter the surfaceenergy balance (SEB) via changes in the turbulent fluxes and earlier snow melt-out in spring.However, modeling these fluxes in complex mountain terrain remains challenging due to sparsedata, scale interactions (e.g., thermally driven circulations), and variable surface conditions,especially from the seasonal snow cover.

Here, we present results from a detailed case study at the heavily instrumented Murtèl rockglacier in the southeastern Swiss Alps, which is an important site for mountain permafrostresearch since the 1970s. The coarse-blocky debris layer (active layer) above the permafrost isseasonally snow-covered and ventilated by air flow through its permeable structure, making thedefinition of “surface” in the SEB time-varying and ambiguous. Using an extensive sensornetwork—from the near-surface atmosphere to the permafrost table, including radiationsensors, eddy-covariance sonic anemometer, snow sensors, and subsurface airflowmeasurements—we unravelled the heat transfer processes including ventilation and computedenergy budgets. Our unique dataset provides rare quantitative insights into turbulent heat fluxesabove and below ground, the snow thresholds required to seal the active layer from theatmosphere, and how air ventilation contributes to self-cooling. Yet, we show that this coolingmechanism is insufficient to maintain thermal stability even in rock glaciers—the most robustpermafrost landforms—under ongoing climate heating.

 

 

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