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

雪板雪崩是指有凝聚力的雪板在一个延伸的薄弱平面上释放出来。积雪地层的原位观测是可靠预测雪坡失稳的必要条件，而雪坡失稳通常是通过雪坑的破坏方法获得的。这阻碍了获取有关积雪演变的信息，并经常使调查人员面临雪崩的风险。因此，高失稳期边坡的原位信息很少得到。本项目研究、采用并推进远程操作的向上雷达系统的应用，以非破坏性图像和表征积雪的局部物理特性，并将其同化到现有的积雪演变模型中。雷达安装在积雪下，随着积雪高度的增加而埋下。由于积雪中的弱层与周围环境具有不同的结构或物理性质，因此向上传播的透射波会被部分反射。对雷达接收到的反射波进行分析，得出积雪的物理特征（内层数和性质、雪厚、密度）。每天重复进行这样的测量，可以对积雪地层学的发展进行准实时和无破坏的监测，并同时提供信息来估计雪崩的危险。该项目为自主监测积雪地层提供了第一步，也可以在潜在不稳定的斜坡上进行监测，而不会给调查人员带来风险。

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.