Snowpack monitoring with upward-looking radar systems towards improved avalanche risk prediction

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Snow slab avalanches involve the release of a cohesive slab over an extended plane of weakness. In-situ observations of snow stratigraphy are necessary for reliable prediction of snow-slope instability, conventionally obtained from destructive methods in snow pits. This hampers acquiring information about temporal snowpack evolution and often exposes the investigator to avalanche risk. Therefore, in-situ information from slopes during high-instability periods are seldom obtained. This project investigates, employs and advances the application of remotely operated upward-looking radar systems to non-destructively image and characterise the local physical properties of the snowpack, and assimilation thereof into an existing model of snowpack evolution. The radar is mounted underneath the snowpack and buried with increasing snow height. As weak layers in the snowpack have different structure or physical properties than their surroundings, transmitted waves traveling upwards through the snowpack are partially reflected. Analyses of reflected waves received by the radar yield a physical characterisation of the snowpack (internal layer number and properties, snow thickness, density). Repetition of such measurements on a daily basis allows for quasi real-time and destruction free monitoring of the development of snowpack stratigraphy and concurrent information to estimate avalanche danger. This project provides an initial step for autonomous monitoring of snow stratigraphy also in potentially unstable slopes without risks for the investigators.