Item: Sensitivity of modeled snow instability to meteorological input uncertainty
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Title: Sensitivity of modeled snow instability to meteorological input uncertainty
Proceedings: International Snow Science Workshop Proceedings 2018, Innsbruck, Austria
Authors:
- Bettina Richter [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Alec van Herwijnen [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Mathias W. Rotach [ Department of Atmospheric and Cryospheric Sciences, ACINN, Innsbruck, Austria ]
- Jürg Schweizer [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
Date: 2018-10-07
Abstract: To perform spatial snow cover simulations for numerical avalanche forecasting, interpolation and downscaling of meteorological data is required, which can introduce uncertainties. The repercussions of these uncertainties on modeled snow instability remain mostly unknown. We therefore assessed the contribution of meteorological input uncertainty on modeled snow instability by performing a global sensitivity analysis. We used the model SNOWPACK to simulate snow instability, i.e. the skier stability index and the critical crack length, for a field site equipped with an automatic weather station providing the necessary input for the model. Uncertainty ranges for meteorological forcing covered typical differences observed within a distance of 2 km and an elevation change of 200 m. Two different scenarios were investigated to better understand the influence of meteorological forcing on snow instability during a) the weak layer formation period and b) the slab formation period. Results showed that during the weak layer formation period, the evolution of weak layer properties and subsequent snow instability were sensitive to all input parameters. In particular, increasing air temperature and increasing precipitation led to higher stability indices. Once a certain weak layer had formed, precipitation was the most prominent driver for snow instability during the slab formation period. While with increasing precipitation the skier stability index decreased, the critical crack length increased. Such findings help with selecting model resolution and complexity, interpreting spatial snow simulations and understanding the evolution of snow instability.
Object ID: ISSW2018_P12.7.pdf
Language of Article: English
Presenter(s):
Keywords: Avalanche forecasting, snow instability, sensitivity, model uncertainties
Page Number(s): 1186-1190
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