Daily high-resolution SnowMicroPen Snow Stratigraphy measurements at a Swiss mountain site

Snow density and specific surface area (SSA) are key parameters controlling snowpack stability, hydrological processes, and surface energy balance. Their accurate simulation is therefore essential for applications ranging from avalanche forecasting to climate modeling. However, these parameters are often time consuming to measure and are available at coarse vertical resolution. The SnowMicroPen (SMP) allows for high-resolution measurements of penetration force from which key microstructural parameters for instance snow density and SSA can be derived using parameterizations such as the one from  [Proksch et al., 2016] or [Calonne et al., 2020]. At the Weissfluhjoch research site located in the eastern Swiss Alps at 2536 m a.s.l, daily SMP measurements have been conducted by the SLF PhD students continuously since winter 2015–2016, resulting in a unique, long-term dataset documenting the seasonal evolution of alpine snowpack at high temporal (daily) and spatial (vertical) resolution.

Here, we present and analyze ten winters (2015–2025) of daily SMP measurements, combined with complementary manual observations, i.e. bi-weekly snow profile measurements, density cutter data, snow water equivalent (SWE) profiles, IceCube SSA measurements, and automated snow and meteorological observations. Post-processing steps, including the identification and correction of sensor offset effects, were applied to ensure comparability of the derived snow properties across the full multi-year dataset. This was crucial, as the data exhibited a clear offset that showed season-dependent behavior and strongly affected derived snow properties, particularly in low density snow ranges. SMP derived snow density and SSA were then evaluated against independent reference measurements across multiple winters.

Snow density showed good agreement with cutter and SWE-derived densities, with the strongest agreement observed for SWE from the full profile and calibration-period cutter data derived by [Calonne et al., 2020]. The SMP is limited to dry-snow conditions. Larger deviations were observed for fresh snow and under warm conditions. For SSA, SMP-derived values showed systematic deviations relative to IceCube measurements, particularly at higher temperatures.
This multi year, high temporal and vertical resolution dataset provides insight into the seasonal evolution of snow stratigraphy, densification, and microstructural changes in an alpine snow. The data allows for analyzing snow layer evolution across multiple winters, and how density and SSA respond to factors such as temperature gradients and densification processes. These findings highlight the potential of the SMP to improve understanding of snow microstructure which helps to improve representations of snow in climate and snowpack models.

References
Neige Calonne, Bettina Richter, H. L¨owe, C. Cetti, J. ter Schure, A. Van Herwijnen, C. Fierz, M. Jaggi, and M. Schneebeli. The rhossa campaign: multi-resolution monitoring of the seasonal evolution of the structure and mechanical stability of an alpine snowpack. The Cryosphere, 14(6):1829–1848, 2020. doi: 10.5194/tc-14-1829-2020.

M. Proksch, N. Rutter, C. Fierz, and M. Schneebeli. Intercomparison of snow density measurements: bias, precision, and vertical resolution. The Cryosphere, 10(1):371–384, 2016. doi: 10.5194/tc-10-371-2016.