Two-dimensional numerical modelling of surface wind velocity and associated snowdrift effects over complex mountainous topography

A new experimental software for blowing snow, SYTRON2, is presented. It takes advantage of the previous limited realization SYTRON1 and of the entire real-time operational environment of the automatic chain SAFRAN Crocus-M-kPRA (SCM). It runs presently on a rectangular grid, with a mesh size of about 45 in, covering an area of 3.0 x 3.0 km(2) around the observation test site Col du Lac Blanc, French Alps (2700 in a.s.l., near the Alpe d'Huez ski resort). SYTRON2 is initialized with a realistic snowpack representation derived from the SCM outputs and coupled to a wind field computed by the new SAMVER model. The final aim is to build a fully embedded tool, suitable for representing snowdrift effects with a better resolution at different specific locations. The different tools and operators used are described, as well as the field validation processes which are based on remote identification of the eroded and accumulated areas using digital pictures.