Numerical Simulation Of Drifting Snow Sublimation In The Saltation Layer

Snow particles can sublime in the ambient undersaturated atmosphere. Sublimation of snow not only affects the mass and crystal structure of snow particle, but also has important influence on snowmelt runoff as an important part of mass-energy balance of snow cover, even induces disasters, particularly, avalanche. Thus is of glaciological and hydrological importance. Compared with surface sublimation, the other way of snow sublimation, drifting snow sublimation is more effective due to the larger surface exposure area of snow particle in the air.Previous studies on drifting snow sublimation mainly focused on suspended snow, and few on saltating snow. In this paper, we first established a saltation model considering the coupling effect between wind and snow particles, then evaluated sublimation of every snow particle based on the sublimation rate expression of a single ice sphere to simulate drifting snow sublimation in the saltation layer. The process of drifting snow sublimation in the saltation layer is showed. We find that the sublimation rate of saltating snow increases linearly with the friction velocity. Moreover, we also find that drifting snow sublimation in the saltation layer plays a very important role in the whole sublimation of snow. On this basis, the balance equations for heat and moisture are established to study the thermodynamic feedback effects under the coupling effects of wind field-snow particles-temperature field and many factors affecting, and the effects of different moisture transport mechanisms on drifting snow sublimation are also analyzed. The results show that effective moisture transport, for example advection, can highly weaken the negative feedback to make sublimation occur for extended periods of time. We also find that the particle number density is an important controlling factor on the sublimation rate. Furthermore, the volume sublimation rate of saltating particles is even several orders of magnitude larger than that of suspended particles. Thus, we once again verify the importance of drifting snow sublimation in the saltation layer on the distribution and the mass-energy balance of snow cover. Therefore, drifting snow sublimation in the saltation layer cannot be neglected and deserves more attention to do further research on it.