Towards a new chain of models for avalanche hazard forecasting in French mountain ranges, including low altitude mountains

Abstract

Operational avalanche hazard warning carried out by Meteo-France for the three main mountain ranges (Alps, Pyrenees, Corsica) have used snow simulations based on the SAFRAN- Crocus-MEPRA (SCM) model chain, for over a decade. Mid-altitude mountain ranges (Massif-Central, Vosges, Jura), culminating below 2000 meters, were until now not considered. Crocus has recently been incorporated in the Earth surface platform SURFEX as one of the snowpack schemes of the land surface model ISBA. This allows in particular to explicitly represent interactions between snow and the underlying soil. Such an improvement makes possible to use Crocus under conditions where the state of the soil may have a significant impact on the properties of snow, which is particularly true for low altitude regions, where the snowpack is shallower and more ephemeral. A new version of the SCM model chain, renamed SAFRAN-SURFEX-MEPRA should replace SCM for all operational appli- cations in the near future. Here we present a comprehensive evaluation of the performance of this new model chain, not only for Alps, Pyrenees and Corsica, but also for mid-altitude mountain ranges. Models are evaluated against ground-based measurements of snow depth gathered at over 150 loca- tions in all considered mountain ranges.