Simulations of 21st century snow response to climate change in Switzerland from a set of RCMs

摘要

Twenty-first century snow depth and snow water equivalent (SWE) changes are assessed for three time periods (2020-2049, 2045-2079 and 2070-2099) at 11 stations in Switzerland with the physics-based snow model SNOWPACK and meteorological input data perturbed by the output from ten regional climate models (RCMs) through the delta change method. Unlike in previous studies, incoming long-wave radiation has also been modified for future climatic conditions. We thus show the range of future snow simulations assuming different RCM projections. Model validation yields satisfying results for simulating snow depth and SWE for the reference period with errors in the order of 9% and 15%, respectively. For the end of the century, the stations between 1000-1700m a.s.l. show no pronounced elevation dependence but surprisingly react quite similarly in terms of the relative magnitude of snow cover decrease, which may reach 90%. The projected small increase in winter precipitation has almost no effect at these stations, but incoming long-wave radiation has an important effect. At the high-elevation station Weissfluhjoch (2540m a.s.l.) however, the precipitation increase is partly able to compensate for the increased temperature. This would imply that the snow cover at mid-elevation stations becomes temperature and radiation dominated and will react similarly to the spatially small differences in the projected temperature change. The low-elevation stations already show a strong decrease in the near future, and the inclusion of modified incoming long-wave radiation has almost no effect on the decrease of future snow depth and SWE because the temperatures are already close to the melting point in the reference period. At the end of the century, mean snow depth/SWE are reduced by 35/32%, 83/86% and 96/97% at high-, mid- and low-elevations, respectively.