Measurement campaigns to investigate blowing snow and snow drift conditions at a high altitude site

[Departement_IRSTEA]Eaux [TR1_IRSTEA]RIVAGE

International audience

إنجليزي. In order to make progress in avalanche research and to improve avalanche risk forecasting, at least two elements must be taken into account: the investigation of the spatial variability of snow depth and the study of meteorological conditions during blowing snow events in high alpine areas. Numerical models (NEMO, Sytron 2 & 3) have been developed to simulate the redistribution of the snow pack during those events. More recently, we tested the ability of a meso-scale atmospheric model to explicitly simulate wind-induced snow transport in alpine terrain. The characteristics and mechanisms of blowing snow events must be verified and the results of the models can then be validated through the use of in-situ measurements. Over the last two years we have successfully performed intensive measurement campaigns at our experimental site (Col du Lac Blanc, French Alps, 2,700 m asl). We followed the evolution of snow depth over an area of 2x1 km² around our experimental site using data from a Terrestrial Laser Scanner. In addition, in-situ measurements were collected during blowing snow events: - Vertical profile of snow fluxes using mechanical traps and Snow Particles Counters (SPC), - Vertical profile of wind velocity, air temperature and relative humidity on a meteorological mast, - Wind speed and air temperature at three automatic weather stations. These measurements represent a whole dataset suitable for the evaluation of models that simulate wind-induced snow transport in alpine terrain. We present in this paper the first results of this in-situ study.