A simulation of a large-scale drifting snowstorm in the turbulent boundary layer

Abstract

Drifting snowstorms are an important aeolian process that reshape alpine glaciers and polar ice shelves, and they may also affect the climate system and hydrological cycle since flying snow particles exchange considerable mass and energy with air flow. Prior studies have rarely considered full-scale drifting snowstorms in the turbulent boundary layer; thus, the transportation feature of snow flow higher in the air and its contribution are largely unknown. In this study, a large-eddy simulation is combined with a subgrid-scale velocity model to simulate the atmospheric turbulent boundary layer, and a Lagrangian particle tracking method is adopted to track the trajectories of snow particles. A drifting snowstorm that is hundreds of meters in depth and exhibits obvious spatial structures is produced. The snow transport flux profile at high altitude, previously not observed, is quite different from that near the surface; thus, the extrapolated transport flux profile may largely underestimate the total transport flux. At the same time, the development of a drifting snowstorm involves three typical stages, rapid growth, gentle growth, and equilibrium, in which large-scale updrafts and subgrid-scale fluctuating velocities basically dominate the first and second stages, respectively. This research provides an effective way to gain an insight into natural drifting snowstorms.