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Effect of unsteady wind on drifting snow: first investigations
1CEMAGREF-ETNA, BP.76 Domaine Universitaire, F-38402 Saint Martin d’Hères, France
2Swiss Federal Institute for Snow and Avalanche Research SLF, Flüelastr. 11, CH-7260 Davos, Switzerland
3METEO-FRANCE, Centre d’Etudes de la Neige, 1441 rue de la piscine, F-38406 Saint Martin d’Hères Cedex, France
Abstract. Wind is not always a steady flow. It can oscillate, producing blasts. However, most of the current numerical models of drifting snow are constrained by one major assumption: forcing winds are steady and uniform. Moreover, very few studies have been done to verify this hypothesis, because of the lack of available instrumentation and measurement difficulties. Therefore, too little is known about the possible role of wind gust in drifting snow. In order to better understand the effect of unsteady winds, we have performed both experiments at the climatic wind tunnel at the CSTB (Centre Scientifique et Technique des Bâtiments) in Nantes, France, and in situ experiments on our experimental high-altitude site, at the Lac Blanc Pass. These experiments were carried out collaboratively with Cemagref (France), Météo-France, and the IFENA (Switzerland). Through the wind tunnel experiments, we found that drifting snow is in a state of permanent disequilibrium in the presence of fluctuating airflows. In addition, the in situ experiments show that the largest drifting snow episodes appear during periods of roughly constant strong wind, whereas a short but strong blast does not produce significant drifting snow.
Key words. Drifting snow, blowing snow, gust, blast, acoustic sensor
Full Article (PDF, 989 KB)
Citation: Michaux, J.-L., Naaim-Bouvet, F., Naaim, M., Lehning, M., and Guyomarc’h, G.: Effect of unsteady wind on drifting snow: first investigations, Nat. Hazards Earth Syst. Sci., 2, 129-136, 2002. Bibtex EndNote Reference Manager
