Project

Discipline

snow cover; climate change; winter tourism; snow water equivalent; snow hydrology; snow climatology; extreme value analysis; trend analysis; snow avalanches

Lead
Lay summary
The inter-annual variability of the snow depth in alpine country like Switzerland is high. On the one hand, we experienced the impact of snow scarcity during the warm and dry early 1990's and again in winter 2006/2007. On the other hand, the snowy winters 1998/1999 and 2008/2009 reminded us that snow still bears considerable hazards such as heavy loads on infrastructure, traffic closures, spring flooding and avalanches. Both situations led to widespread discussions about the impact of climate change on snow and its high relevance for an Alpine country like Switzerland. The objective of the proposed research project is therefore to constitute the first comprehensive study of snow depth and snow water equivalent for Switzerland which will analyse the full record up to now. Moreover, our goal is to obtain future snowpack scenarios resolving the different regions using a state of the art snow-cover model with input from the newest regional climate models (RCMs). The study consists of two parts, which together will provide new insights on past and future changes of the Swiss snowpack. Newly digitized and existing data will be joined and analyzed for trends and shifts in mean, extremes and variability. A special focus will be given to the spatial extreme value analysis of the different parameters and whether snow water equivalent records show similar signatures of climate-related variability, as is the case with snow depth records.In the second part today's average snow cover will be assessed based on simulations using the snow-cover model SNOWPACK for a set of sites that feature both meteorological model input data and snow data for validation. Hence, all model results can be verified and accuracies can be quantified. In a second step meteorological data representative of future climate will be deduced from RCMs. These data serve as input data for SNOWPACK runs that allow an assessment of the future seasonal snow in the Switzerland. The results will be of high relevance for environmental impact assessments and adaptation measures, which are increasingly necessary in warming Alpine regions, where economy and ecology is strongly linked to the availability of snow.

Direct link to Lay Summary

Last update: 21.02.2013

Active participation

Active participation

Self-organised

Communication	Title	Media	Place	Year

Number	Title	Start	Funding scheme

The high inter-annual variability of the snow depth proves that it is very sensitive to the prevailing meteorological conditions. On the one hand, we experienced the impact of snow scarcity during the warm and dry early 1990’s and again in winter 2006/2007. On the other hand, the snowy winters 1998/1999 and 2008/2009 reminded us that snow still bears considerable hazards such as heavy loads on infrastructure, traffic closures, spring flooding and avalanches. Both situations led to widespread discussions about the impact of climate change on snow and its high relevance for an Alpine country like Switzerland. However, due to missing data the snow cover in Switzerland has so far only been analyzed back to the 1930’s whereas the latest snow climatological study on snow water equivalent (SWE) data dates back to 1992. Moreover, recent investigations on the possible developments of the future Alpine snowpack are mostly case studies and cannot be compared due to the different approaches used. The objective of the proposed research project is therefore to constitute the first comprehensive study of Switzerland which, regarding snow depth, goes back to the end of the 19th century and regarding snow water equivalent, allows analysing the full record up to now. Moreover, our goal is to obtain future snowpack scenarios resolving the different regions using a state of the art snow-cover model with input from the newest regional climate models (RCMs) and latest downscaling techniques. The scenarios will be based on thoroughly validated reference runs. The study consists of two parts, which together will provide new insights on past and future changes of the Swiss snowpack. 1. Past changes: Recently discovered old datasets of snow depth back to the 19th century from different archives will be digitized. Data gaps in existing long-term time series will be filled based on recently developed interpolation methods. Newly digitized and existing data will be joined and analyzed for trends and shifts in mean, extremes and variability. A special focus will be given to the spatial extreme value analysis of the different parameters and whether snow water equivalent records show similar signatures of climate-related variability, as is the case with snow depth records.2. Future snowpack: First, today’s average snow cover accumulation and depletion dynamics for different altitudes and regions will be assessed based on respective simulations using the 1-D snow-cover model SNOWPACK for a representative set of sites that feature both meteorological model input data and snow data for validation. Hence, all model results can be verified and accuracies can be quantified, before the model estimations will be used as a reference for subsequent model runs representing snow cover dynamics using IPCC climate change scenarios. Therefore, meteorological data representative of future climate will be deduced using changes as predicted by ensembles of latest RCM runs. These data serve as input data for model runs that allow an assessment of the impact of climatic change on seasonal snow in the Switzerland. A methodological emphasis will be set to refined stochastic downscaling methods coupling RCM data to observed meteorological data records.The results will be of high relevance for environmental impact assessments and adaptation measures, which are increasingly necessary in warming Alpine regions, where economy and ecology is strongly linked to the availability of snow.