Wind transport of snow

Abstract

Physically-based models describing the flow of blowing snow are developed and presented. The models calculate the mass transport of snow as saltating and suspended flow and the rate of sublimation of snow in transport. The saltation expression is calibrated using field measurements of horizontal mass flux near the snow surface, which show an approximately linear increase with wind-speed. The suspension expression is calibrated from field measurements of the horizontal mass flux at heights from near the surface to two metres, which show an exponential increase with the wind-speed. Sublimation of blowing snow is calculated based on a consideration of heat and water vapour fluxes at the particle surface. Sublimation rates increase exponentially with wind-speed and increase by an order of magnitude as the air temperature increases from -35 °C to -1 °C or the relative humidity decreases from 95% to 40%.

The expressions are compiled in a mass-balance model, termed the Prairie Blowing Snow Model, which calculates the horizontal mass flux and sublimation rate of blowing snow and the erosion rate at the surface. The Model uses standard meteorological station measurements and terrain data as inputs. The distance over which snow may blow without obstruction is shown to be an important parameter affecting the surface erosion rate. For distances less than 400 to 500 m the erosion rate is controlled by the magnitude of the horizontal mass flux, while for greater distances the sublimation rate controls erosion.