The RHOSSA campaign: Multi-resolution monitoring of the seasonal evolution of the structure and mechanical stability of an alpine snowpack

Abstract

<p>The necessity of characterizing snow through objective, physically-motivated parameters has led to new model formulations and new measurement techniques. Consequently, essential structural parameters such as density and specific surface area (for basic characterization) or mechanical parameters such as the critical crack length (for avalanche stability characterization) gradually replace the semi-empirical indices acquired from traditional stratigraphy. These advances come along with new demands and potentials for validation. To this end, we conducted the RHOSSA field campaign, in resemblance of density (ρ) and specific surface area (SSA), at the Weissfluhjoch research site in the Swiss Alps to provide a multi-instrument, multi-resolution dataset of density, SSA, and critical crack length over the complete winter season 2015-2016. In this paper, we present the design of the campaign and a basic analysis of the measurements alongside with predictions from the model SNOWPACK. To bridge between traditional and new methods, the campaign comprises traditional profiles, density cutter, IceCube, SnowMicroPen (SMP), micro-computed-tomography, propagation saw tests, and compression tests. To bridge between different temporal resolutions, the traditional weekly to bi-weekly snow pits were complemented by daily SMP measurements. From the latter, we derived a re-calibration of the statistical retrieval of density and SSA for SMP version 4 that yields an unprecedented, spatio-temporal picture of the seasonal evolution of density and SSA in a snowpack. Finally, we provide an inter-comparison of measured and modeled estimates of density and SSA for 4 characteristic layers over the entire season to demonstrate the potential of high temporal resolution monitoring for snowpack model validation.</p>

A random forest model to assess snow instability from simulated snow stratigraphy

“…Both physically based models are driven with meteorological data from either automatic weather stations or numerical weather prediction models (e.g., Bellaire and Jamieson, 2013;Quéno et al, 2016) and provide microstructural (e.g., grain size) and macroscopic (e.g., density) properties for each snow layer. Validation campaigns have demonstrated a reasonably good agreement between modeled and observed snow stratigraphy (e.g., Durand et al, 1999;Lehning et al, 2001;Monti et al, 2009;Calonne et al, 2020) and, in particular, have confirmed the models' capability to reproduce critical snow layers such as surface hoar (Bellaire and Jamieson, 2013;Horton et al, 2014;Viallon-Galinier et al, 2020). From the basic model output, different mechanical properties can be calculated.…”

Snowfall and snow accumulation during the MOSAiC winter and spring seasons

“…Proksch et al (2015), whileCalonne et al (2020) used 1 mm andKing et al (2020) 5 mm. However, the strength of the influence can be at least partially invalidated by the fact thatCalonne et al (2020) state that they tested for sensitivity of three different window sizes of 1, 2.5 and 5 mm and could not find a significant influence on the result -which is not quantified in the publication. At least choosing a fixed window for each parameterization -as we did with the 2.5 mm windowincreases the comparability.…”

“…At least choosing a fixed window for each parameterization -as we did with the 2.5 mm windowincreases the comparability. Another limitation might be that theProksch et al (2015) calibration was made with a SMP version 2, while we,Calonne et al (2020) andKing et al (2020) use the newest SMP version 4.…”

Fingerprints of Frontal Passages and Post‐Depositional Effects in the Stable Water Isotope Signal of Seasonal Alpine Snow

“…In winter 2017, the campaign to monitor the isotope signal in the snowpack took place from January to June (Figures 1a and 1b). In parallel to the isotope profile sampling campaign, an extensive measurement program to characterize the snow cover at the WFJ site took place (Calonne et al., 2020).…”