Department of Applied Geomatics
University of Sherbrooke
Alexandre Langlois (Regular member)
Introduction New avalanche risk assessment methods need to be developed to support the development of backcountry sports. Indeed, the current risk assessment methods are very localized, require a lot of time and financial resources. In addition, climate change directly influences the increase in ambient temperatures causing a change in the types of precipitation. Rain on snow events are observed which changes the nature of the stratigraphy of the snowpack. Also, the number of mountain sports practitioners has been increasing over the past decades, which increases the frequency of visits to avalanche terrain. The 24 GHZ FMCW radar is a tool for analyzing the stratigraphy of the snowpack in a non-destructive manner. It could be used on a larger spatial scale than traditional methods and is much faster. Objectives The main objectives of this research are to: develop an algorithm for detecting the stratigraphy of alpine snow cover including quantification of total thickness, individual thickness and density of layers using a 24 GHZ FMCW radar; ealuate the temporal behaviour (duration, variation in thickness) of snowpack layers and the potential impact of this variability on instability using the algorithm; spatialize the stratigraphy using a mobile radar assembly (drone/snowmobile) and assess the potential of a 3D interpolation of the radar signal in understanding the factors conditioning stratigraphy at the local scale. Study sites Two study sites were selected for this research. The first study site is Mount Fidelity in the Glacier National Park in British Columbia and the second is Mount Albert located in the Gaspé National Park in Quebec. Mount Fidelity is home to a research station that is closed to the public and receives the vast majority of dry snowfall during the winter. At Mont Albert, the research area is located near the serpentine station. In winter, the Gaspé climate is marked by a large variation in temperature leading to rain on snow events. Material and methods Two different methods will be carried out in the field to measure the spatio-temporal variability of the stratigraphy of the snowpack. To measure spatial variability, a mobile setup with a 24 GHZ FMCW radar will be used to probe a defined area. Cross sampling, consisting of a horizontal transect and a vertical transect, will create a grid where radar profiles will be taken along the transects. Then, the shape of the grid will allow to create a random sampling where several radar profiles will be taken in the four quadrats of the grid. To measure the temporal variability, a fix assembly with an FMCW 24 GHZ radar aiming at the ground will make it possible to take data on the snowpack throughout the season. References Laliberté, J. (2021) Détection de la stratigraphie en milieu de neige sèche à l’aide d’un radar à onde continue modulé en fréquence (FMCW) de 24 GHz, p. 78. Madore, J.-B. (2016) Évaluation de la modélisation de la taille de grain de neige du modèle multi-couches thermodynamique SNOWPACK: implication dans l’évaluation des risques d’avalanches, p. 75. Marshall, H.-P., Schneebeli, M. et Koh, G. (2007) Snow stratigraphy measurements with high-frequency FMCW radar: Comparison with snow micro-penetrometer. Cold Regions Science and Technology, vol. 47, n°1‑2, p. 108‑117. Pomerleau, P., Royer, A., Langlois, A., Cliche, P., Courtemanche, B., Madore, J.-B., Picard, G. et Lefebvre, É. (2020) Low cost and compact FMCW 24 GHz radar applications for snowpack and ice thickness measurements. Sensors, vol. 20, n°14, p. 3909.
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