Multiscale modeling of heat and mass transfer in dry snow: influence of the condensation coefficient and comparison with experiments

Abstract. Temperature gradient metamorphism in dry snow is driven by heat and water vapor transfer through snow, which includes conduction/diffusion processes in both air and ice phases as well as sublimation and deposition at the ice-air interface. The latter processes are driven by the condensation coefficient α, a poorly constrained parameter in literature. In the present paper, we use an upscaling method to derive heat and mass transfer models at the snow layer scale according to α in the range 10⁻¹⁰ to 1. A transition α-value arises, of the order of 10⁻⁴ for typical snow microstructures (characteristic length ∼ 0.5 mm), such as the vapor transport is limited by sublimation-deposition below that value and by diffusion above. Accordingly, different macroscopic models with specific domains of validity with respect to α-values are derived. A comprehensive evaluation of the models is presented by comparing with three experimental datasets as well as with pore-scale simulations using a simplified microstructure. The models reproduce the two main features of the experiments: the non-linear temperature profiles, with enhanced values in the center of the snow layer, and the mass transfer, with an abrupt basal mass loss. However, both features are overall underestimated by the models when compared to the experimental data. We investigate possible causes of these discrepancies and suggest potential improvements for the modeling of heat and mass transport in dry snow.