Item: Changes in spatial patterns of snow stability through time
Title: Changes in spatial patterns of snow stability through time
Proceedings: 2002 International Snow Science Workshop, Penticton, British Columbia
Authors: Karl W. Birkeland and Chris C. Landry, U.S. Forest Service National Avalanche Center Department of Earth Sciences, Montana State University
Abstract: The spatial variability of snow stability presents a challenge to avalanche workers and scientists attempting to assess avalanche danger. Recent research has demonstrated, and attempted to explain, snowpack and snow stability variations over individual slopes. However, these studies have provided single snapshots of an exceedingly dynamic system instead of investigating stability variations over time. This research begins to address how spatial variability at the local slope scale changes through time and the some possible mechanisms for those changes. We performed ten Quantified Loaded Column Tests (QLCTs) in each of five snowpits within a 900 m2 plot on a relatively uniform slope on three different days. We make a case that the behavior of the snow avalanche system is consistent with complex, nonlinear Earth Surface Systems (ESSs), and that research into ESS behavior in other fields might prove to be useful for examining changes in spatial variability through time. In particular, ESSs are typically characterized by sensitivity to initial conditions, which leads to increasing spatial variability through time. Our series of three QLCT trials exhibited changing stability patterns, suggesting that the spatial variability on a slope may increase through time in the absence of external forcing, but that variability may then decrease when additional load is added to the slope. This research provides some interesting initial insights into changes in spatial variability for practitioners and provides some baseline data for future scientific work in this area.
Keywords: spatial variability, snow stability, avalanche, avalanche forecasting
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