Modeling and measuring glacier-wide snow redistribution at Hintereisferner

The representation of the snow cover dynamics (including accumulation, redistribution, and compaction), due to their impact on the snow-albedo feedback, poses the central deficiency in distributed mass balance models for most temperate and land-terminating glaciers. Data quantity and quality both from ground measurements and from remote sensor systems have not yet been sufficient to resemble these actual processes on a glacier scale until now. This limits the calibration and evaluation of distributed mass balance models.

Yet, we installed a permanently terrestrial laser scanning (TLS) system at the Hintereisferner glacier (Ötztal Alps, Austria), which provides a daily digital elevation model (DEM). These DEMs with an accuracy of about ±10 cm can serve as calibration and validation data of distributed glacier mass balance models.

We present a case study of snow cover dynamics between 6 and 9 February 2021. Snow fall of approximately 50 cm was registered and moderate wind speeds were measured on these days. Furthermore, wind-blown snow and small avalanches are visible on the webcam pictures. Three high-quality DEMs (e.g. no clouds) were taken on these days. The snow fall and snow redistribution thereafter can be reconstructed with the these DEMs and data from automatic weather stations on Hintereisferner and its surrounding slopes. To support the process analysis, we simulated the case study days with the Weather Research and Forecasting model (WRF) with a high-resolution setup of dx=48m. A recently implemented snow drift module allows to assess and understand wind-driven snow redistribution on the glacier.

This high-resolution set-up, both on the observational and modelling side, allows an improved understanding of snow distribution over glaciers and has the potential to be applied at other glaciers as well.