Theoretical and Numerical Modeling of the Wind-driven Emission of Snow Fragments and Dust Aggregates

When wind-blown snow and sand particles impact their granular or sintered beds, their kinetic energy controls the velocity- and size distribution of emitted fragments. A correct simulation of the emitted particle size distribution in sand and snow transport models is essential for the assessment of the surface mass balance over arid soils and Antarctic ice sheets. Although recent theoretical advances have shed light on the size distribution of emitted dust aggregates, not much is known about snow fragmentation. We therefore propose a scaling theory for the size distribution of emitted snow particles, based on the brittle behavior and fractal geometry of ice crystals. The theoretical distributions of emitted snow fragments and dust aggregates are accounted for in a detailed sediment transport model, based on large-eddy simulation and Lagrangian stochastic description of particle dynamics. Simulations of sand and snow transport in fully-developed boundary layer flows are carried out to quantify the influence of fragmentation processes on dust aerosols emission and snow sublimation.