Etude en soufflerie climatique (Cryospheric Environment Simulator) de l'influence du type de grain de neige et du régime d'écoulement sur la formation d'une congère

Study in a climatic wind tunnel (Cryospheric Environment Simulator) of the influence of the type of grain of snow and of the flow on the formation of a snow-drift

¹ Division ETNA, Cemagref, 2 rue de la papeterie, BP 76, 38402 Saint-Martin d'Hères, France
² Shinjo Branch of Snow and Ice Studies, National Research Institute for Earth Science and Disaster Prevention, Japon

Abstract

The transport of snow by the wind presents many problems in terms of winter viability and risk of avalanche. Until now, the numerical modeling of this phenomenon, considered only a regular wind, and one type of particle. In order to improve this modeling, we sought to know the influence of the type of grain of snow and the mode of flow during an episode of transport of snow by the wind. To this end, we carried out experiments with the climatic wind tunnel of Shinjo Branch of Snow and Ice Studies in Japan. We studied the effect of the mode of flow and the type of grain of snow on the speed of formation and the shape of a snow-drift around a model of snow barrier, like on the density of the deposit. These experiments highlight that the process of formation of the deposit is closely related to the type of transported particles. The type of grain of snow transported can vary in a significant way the speed of formation of the deposit, the volume of snow deposited like its density. Of more, these studies made it possible to determine the influence of the mode of flow in the process of formation of a snow-drift : this one is formed more quickly by regular wind than by gusts, but with saturation the generated deposits are identical. It thus appears that the nature of the flow, in gust or by regular wind does not intervene on the form of the deposit with saturation, but on the speed of formation of the deposit.