Sublimation during drifting and blowing snow events

Snow drift in complex terrain is able to transport large amounts of snow through the air, leading to a redistribution of the snow cover. Wind deposition of snow plays an important role in avalanche formation. Several studies have shown that sublimation of drifting snow particles can remove significant amounts of snow from the air during transport, reducing the amount of snow deposited on lee slopes or on large high latitudes snow fields.The sublimation of drifting snow particles is studied by analyzing humidity measurements from a cold wind tunnel. It was found that the water vapor content of the air increases more when snow drift was present in the wind tunnel compared to situations without snow drift. An important factor determining the total amount of sublimation appeared to be the particle number density. Increased sublimation was observed if shortwave radiation was present. The wind tunnel experiments were simulated using a 1D numerical model for atmospheric boundary layers. Experiments and model results showed a good agreement and confirmed earlier assumptions on the effect of snow sublimation during drift.This model was also used to calculate the snow drift sublimation for a 3D snow drift model suitable for complex terrain. The feedback mechanisms of snow drift sublimation (cooling and humidifying of the air) reduce the sublimation rate significantly. Explicitly calculating the feedback mechanisms requires a lot of computational effort. However, a simple parameterization can be developed based on initial conditions before the snow drift event. This parameterization yields satisfying results for a test case.