Item: The effect of daytime warming on snowpack creep
Title: The effect of daytime warming on snowpack creep
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors: Thomas Exner and Bruce Jamieson, Department of Geoscience, University of Calgary, Cananda, Departnment of Civil Engineering, University of Calgary, Canada
Abstract: Snowpack warming is, besides loading by precipitation and wind-transport, one of the major triggers contributing to natural avalanche release. Established release mechanisms for spontaneous slab avalanches strongly depend on deformation rates in weak layers, which are affected by temperature changes. Once a critical rate is exceeded snow exhibits strain softening and ultimately brittle fracture. Failure of a weak layer is an important prerequisite to slab avalanche release. Critical slope parallel deformation rates may be reached in weak layers on sufficiently steep slopes due to increased creep in the overlying slab, which is heated by solar radiation. Using time lapse photography during the transition from cold mornings to warm sunny afternoons, we monitored vertical and slope parallel displacements of markers on a vertical snow profile on steep slopes. In a case study we present time series of displacements that showed increased snowpack creep and slope parallel deformation rates during solar heating of the near surface layers.
Keywords: snowpack creep, daytime warming, stability, field measurements, avalanche forecasting
Digital Abstract Not Available