Abstract ID: 28.7306 | Accepted as Poster | Poster | 2025-02-27 13:00 - 14:30 | Ágnes‐Heller‐Haus/Small Lecture Room

The importance of firn structure, mainly firn density, in glacier mass balance estimation has been limited and highly reliant on modelling approaches, particularly in challenging alpine conditions. This study focuses on comprehending firn structures and their density-depth profiles in the Aletsch glacier’s accumulation area using Ground Penetrating Radar (GPR) as a geophysical tool, supported by glaciological methods and firn compaction models. We sought to characterize the firn structure and ascertain the spatial firn density-depth profiles. We estimated the electromagnetic wave velocities by picking the reflection hyperbolae from semblance analysis using the Common Midpoint method (CMP). We obtained three density-depth profiles at three locations in the accumulation area. We tested firn compaction models chosen from community firn models (CFM), particularly Ligtenbergetal (LIG) and Kuipers Munnekeet (KM). By forcing the regional climatic conditions, model parameter coefficients were tuned to fit the estimated 1-D firn density profiles from CMP gather. We also present a method to estimate the accumulation history by chronologically identifying the GPR-derived internal reflection horizons (IRHs) as annual firn layers, validating against the stake-measured snow water equivalent (SWE). We also obtained a spatial GPR transect covering a 1.8 km length to track the spatial firn density and accumulation history. Our study shows the potential of GPR, along with direct measurements and modelling results, in tracking firn structures and firn density in temperate glacier conditions.