A comparison of the spatial structure of the penetration resistance of snow layers in two different snow climates

Abstract. This paper compares the spatial structure of the compressive strength of slab and weak layers from two different snow climates. Our data come from arrays of SnowMicroPen (SMP) measurements in southwestern Montana, USA, and near Davos in eastern Switzerland. In both cases, buried surface hoar comprised the critical snowpack weakness. We analyzed the SMP data by manually delineating the surface hoar layers and a number of layers within the slabs above the weak layers. Using the log-10 transformed mean of the penetration resistance for our layers of interest, we investigated the spatial structure of the data by looking for linear slope-scale trends and assessing the residuals of any trends with semivariograms. Our results demonstrate that the layers investigated had variable spatial structures, both in terms of their linear trends and their semivariograms. This suggests that each snowpack layer has a unique spatial structure possibly arising from its depositional pattern and the subsequent changes to the layer when buried. We also demonstrate that the specific layout used for the measurements strongly influences the observed spatial variability. The complicated spatial structures of individual layers, and how they interact, likely contributes to the sometimes confounding overall patterns of spatial variability of stability observed on snow slopes