Item: Predicting snow cover stability with the snow cover model snowpack
Title: Predicting snow cover stability with the snow cover model snowpack
Proceedings: Proceedings of the 2006 International Snow Science Workshop, Telluride, Colorado
Authors: Sascha Bellaire, Jürg Schweizer, Charles Fierz, Michael Lehning and Christine Pielmeier, WSL, Swiss Federal Institute for Snow and Avalanche Research SLF, Davos, Switzerland
Abstract: The snow cover model SNOWPACK simulates snow stratigraphy for the locations of automatic snow and weather stations. Based on the stratigraphy, snow stability is predicted by calculating three stability indices. We verified the performance of the skier stability index SK38 in order to develop a supporting tool for avalanche warning services. Since stability depends on snow stratigraphy, modelled grain type, grain size, hardness and density were first validated. The skier stability index SK38 performed poorly in terms of identifying potential weak layers. By introducing a new stability formulation (SSI) that combined the SK38 with differences of hardness and grain size across layer interfaces – known indicators of structural instability – the model performance was substantially improved. For manually observed flat field profiles, the SSI was significantly related with stability test results. At the regional scale, a statistically significant relation between predicted and verified stability was found. Stability patterns at the mountain range scale were reproduced. With these improvements the snow cover model SNOWPACK will develop into a valuable supporting tool for stability evaluation as done by avalanche warning services.
Keywords: avalanche forecasting, snow cover modelling, snow stability evaluation, numerical simulation
Digital Abstract Not Available