Numerical modeling of blowing and drifting snow in Alpine terrain.

Abstract

In mountainous regions, snow transport due to wind significantly influences snow distribution and, as a result, avalanche danger. A physically based numerical two-Iayer model is developed to simulate blowing and drifting snow in Alpine terrain. One layer describes the driving-wind field and the transport in suspension. The description is based on the atmospheric boundary-Iayer equations, using an e-E model for the turbulent closure. The second layer describes the transport due to saltation, including erosion and deposition of snow. Here, conservation equations for mass and momentum are formulated for the mixture of snow and air. Particle trajectory calculations are used to parameterize quantities characterizing the saltation layer. Both layers are mutually coupled by boundary conditions. A two-way coupling between particles and airflow is taken into account. Comparisons between simulation results and field measurements around an Alpine crest show encouraging results.