Turbulent Advection Processes in Blowing Snow Sublimation

Snow redistribution by wind has significant effects on the depth and location of snow water equivalent. This in turn impacts the volume and timing of snowmelt and meltwater runoff, a vital contributor of freshwater to large proportions of the world’s population. Snow redistribution is a difficult phenomenon to model as transport rates depend on many scales of motion in the atmospheric boundary layer. This process is further complicated by in-transit sublimation of blowing snow due to vapour pressure gradients around and ventilation of individual blowing snow particles. Current models of blowing snow sublimation that incorporate thermodynamic feedbacks often rely on steady-state assumptions and minimize the role of air entrained from the atmosphere towards the snow surface. This can lead to modelled water vapour saturation in blowing snow layers – in contrast to many field observations. The assumptions potentially underestimate the magnitude of sublimation. This study focusses on the degree of turbulent atmospheric surface layer mixing and the role of vertical and horizontal entrainment in enhancing near-surface blowing snow sublimation. Through mathematical synchronization of temperature, wind, and blowing snow measurements at an alpine study site, the coupling of inner-layer and outer-layer motions were investigated to improve the understanding of the relevant turbulent mechanisms and estimate their impact on blowing snow sublimation.