Quantitative Snow Stratigraphy and Stability Derived from High-resolution Penetrometry

Precise measurements of snow structural parameters and stratigraphy are essential to understand and model snow physical processes, in particular with respect to avalanche formation. However, most snow measurements are limited in spatial resolution and by extensive measurement times, and therefore lack practicability for avalanche professionals. The snow micro-penetrometer (SMP), a portable, high-resolution penetrometer allows recording vertical profiles of the penetration resistance quickly and reliably, but so far it was not possible to interpret these profiles with regard to stability. We combine a recently developed statistical model to derive the major snow structural parameters and a new method to derive snow stability parameters solely from SMP measurements. We demonstrate the potential of this combined approach by analyzing a 28 m long transect through Alpine snow at the Steintälli, Davos, Switzerland. The transect consisted of 47 SMP measurements which were made perpendicular to a small ridge, thus capturing a classic terrain feature with changing snow depth. The derived structural and stability parameters were in agreement with independent measurements from snow profiles and stability tests. Modeled critical cut length were smaller in the areas with larger snow depth, where the higher load of the slab appeared to be the main driver. The weak layer was located at the transition towards depth hoar at the base of the snowpack, which was consistently present throughout the whole length of the transect. Our approach provides a valuable starting point for further modeling efforts, such as finite element simulations of snow stability at the slope scale.