Snowdrift modelling in a wind tunnel: vertical and horizontal variation of the snow flux

This paper deals with the influence of the vertical and horizontal variation of aeolian snow flux on estimations of snow-storm duration and on snowdrift patterns simulated in a wind tunnel. First of all, we shall review recent developments, including our own simulations, concerning the horizontal increase of mass flux until drifting-snow saturation has been reached. Next, after a critical examination of various snowdrift-modelling criteria, we present the results of an experiment undertaken in our wind tunnel: We studied cross-section drift-area changes behind a small-scale snow fence as a function of time for different fetches but for the same mean wind speed at the beginning of the testing section. For each fetch, we carried out vertical profiles of sand particles using image processing and we studied the geometrical parameters of the drift. We conclude that changes in the cross-section drift area depend on the ablation length and if particle saturation is not reached, the use of a storm-duration scale leads to overevaluation of prototype storm duration. Moreover, we point out that drift pattern vary as a function of the concentration profiles.