Temporal Changes in the Spatial Variablility of Snow Stability

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Snow avalanches are a significant hazard in the mountainous environments of the western United States and in alpine regions around the world. Knowledge of spatial variations in snow stability and snowpack properties is critical for understanding and predicting snow avalanches. Although previous research has investigated spatial variability on individual slopes, most studies have simply looked at a single snapshot in time of an extremely dynamic system. This project attempts to fill this gap in fundamental knowledge by measuring and analyzing how the spatial variability of snowpack properties and snow stability vary through time. Preliminary work on this topic suggests that snow stability on a given slope may diverge or become more spatially variable over time as the snowpack stabilizes in the absence of external influences. If a slope is perturbed to the edge of instability, however, the snow stability may converge or become more spatially uniform. This study will utilize a new snow stability test and a sensitive instrument co-developed by the Swiss Federal Institute for Snow and Avalanche Research and the U.S. Army Cold Regions Engineering Laboratory to measure temporal changes in snow stability. Adjacent 900-square meter plots will be sampled through time at variety of field sites. Data analyses will focus on how well snow stability measured in snowpits represents the mean of their respective plot and how spatial patterns of weak layer thickness, strength, and microstructure change through time.The proposed research will address a pressing question for snow avalanche research and prediction, and it will offer new and important information for scientists about how the snowpack evolves and how avalanches release. On a practical level, the work will provide critically relevant insights for avalanche professionals working to protect life and property. The results of this research will enhance techniques for avalanche forecasting. The results also will improve avalanche mitigation efforts that protect ski areas and highway corridors. Finally, this work will benefit society by providing important new information for all people playing in, working in, living in, and traveling through mountain environments.