Item: Spatial variability in steep couloirs: weak layer variation with respect to wind direction
Title: Spatial variability in steep couloirs: weak layer variation with respect to wind direction
Proceedings: 2010 International Snow Science Workshop
Authors: Zach M. Guy1* and Karl W. Birkeland1,2 1Department of Earth Sciences, Montana State University, Bozeman, MT, USA 2USDA Forest Service National Avalanche Center, Bozeman, MT, USA
Abstract: Understanding the spatial variability of the snowpack is critical for avalanche prediction and mitigation. Previous spatial variability research focused primarily on relatively low angle slopes, many of which had fairly uniform characteristics. With snow sports progressing to steeper and more complicated terrain, a need exists to better understand the relationship between this “extreme” terrain and the snowpack variability. This research utilizes nine couloirs from Big Sky, Montana and Teton Pass, Wyoming. We used a probe to measure weak layer heights, slab thicknesses, and snow depths, we cross-verified those measurements with pits, and we georeferenced our sampling points using a submeter accuracy GPS. LiDAR data are used to derive terrain parameters, such as slope, aspect, elevation, and curvature in a GIS, and these data are then compared with our snow observations. Our analyses quantify the distribution of snow in the couloirs, and suggest that weak layer thickness normalized by snow depth is significantly correlated with the distance from the windward boundary when all other terrain parameters are accounted for in our sampled population of couloirs. Our results provide insights into the distribution of weak layers and snow depth in steep couloirs, which is a first step in optimizing snow pit locations and explosive placements in this terrain.
Keywords: steep couloirs, wind direction, geographic information systems (gis)