A 3-D simulation of drifting snow in the turbulent boundary layer

Abstract. The drifting snow is one of the most important factors that affect the global ice mass balance and hydrological balance. Current models of drifting snow are usually one- or two-dimensional, focusing on the macroscopic quantities of drifting snow under temporal average flow. In this paper, we take the coupling effects between wind and snow particles into account and present a 3-D model of drifting snow with mixed grain size in the turbulent boundary layer. The Large Eddy Simulation (LES) method is used for simulating the turbulent boundary layer of the wind field and the 3-D trajectory of every motion snow particle is calculated through Lagrangian Particle Tracking method. The results indicated that the drifting snow in the turbulent boundary layer has apparent 3-D structure and snow streamers, which lead to an intermittent transport of the snow particles and spatial inhomogeneity, and the motion trajectories of snow particles, especially the small snow particles, are obviously affected by the turbulent fluctuation. The macro statistics of drifting snow indicates that the spanwise velocity of snow particles increases with height and is one order smaller than that of streamwise velocity. Furthermore, the diameter distribution of snow particles in the air along the height shows a stratification structure.