Snow cover spatial variability at multiple scales: Characteristics of a layer of buried surface hoar

With the aim of a multi-scale analysis, we simultaneously observed snowpack stratigraphy and stability at three scales: the slope scale, the regional scale and the mountain range scale. The minimum spacing between measurements was 0.5 m and the maximum extent was about 17 km. Field measurements were made during five periods near Davos in the eastern Swiss Alps and focused on a layer of surface hoar. The layer was initially observed on the snow surface where it showed a high degree of spatial continuity. After burial the layer was less spatially continuous. Snow stability and its variation depended on the existence and size of the surface hoar layer. At the slope scale, measurements were made with a micro-penetrometer at a high spatial resolution and showed that the layer of buried surface hoar was spatially continuous at the slope scale. At the regional and mountain range scale various patterns in surface hoar size and presence were observed. A spherical semivariogram model fitted to the regional data gave a range of 500–1500 m. At the mountain range scale the distance of autocorrelation increased to around 10 km. The different lengths of autocorrelation indicate that the observed variability was the result of several physical processes with different typical scales.