Item: In situ and photogrammetric measurements of avalanche crown transects
Title: In situ and photogrammetric measurements of avalanche crown transects
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors: Edward H. Bair, Karl W. Birkeland, and Jeff Dozier, Bren School of Environmental Science & Management, University of California, Santa Barbara, CA, USA, Forest Service National Avalanche Center, US Department of Agriculture, Bozeman, MT, USA
Abstract: We present results on the geometry and depth distributions for transects along the crowns of small to large avalanches. Previous research suggests that power laws in aggregate distributions of crown depths result from observers recording maximum depth. We therefore studied individual crown transects to obtain information about the parent distributions, using in situ and photogrammetric measurements. The geometry shows that crowns are thinnest and decreasing toward the flanks. Depth distributions of individual crowns do not follow power laws. Instead, we find transects fit normal distributions. To reconcile this finding with observed aggregate distributions, we propose a mixture of maxima, taken from normally distributed crown depths, with power law mean parameters. We suggest normally distributed transects arise from spatially-correlated new snow depths.
Keywords: photogrammetry, crowns, power laws, distributions
Digital Abstract Not Available