Mesure de la densité de la neige à partir de ses propriétés acoustiques

Snow density measurement using acoustic properties

¹ Division Nivologie du Cemagref. Actuellement à RTM (Restauration des terrains en montagne), Gap
² Laboratoire d'instrumentation, de micro-informatique et d'électronique de l'Université J. Fourier, Grenoble
³ Centre d'Etude de la Neige, Grenoble

Abstract

Today, it is possible to measure the density of the snow by different, ways; attenuation of gamma rays, absorption of electromagnetic waves... In this paper, we suggest a simple method to estimate the density of the snow from its acoustic properties. After some basic recalls about the propagation of the sound in a continuous medium, we show the links observed from laboratory experiment, between the density and the acoustic parameters of the snow. A good correlation is found between the density and the modulus of the impedance. The use of a mathematical model of the propagation of an acoustic wave through a porous medium allows us to calculate the density of the snow from its acoustic, porosity. Therefore, it will be easier for field measurements and more efficient to use a simple method based on the empirical relations which we obtained and we propose the principle of an acoustic sensor to estimate in the snow cover, the density of the snow.