Determining snow water equivalent by acoustic sounding

Abstract

Abstract The possibility of determining snow water equivalent (SWE) by the use of an acoustic impulse was assessed at two field locations in Saskatchewan and British Columbia, Canada. These sites represent cold windswept prairie and temperate deep mountain snowcovers. A continuous frequency‐swept acoustic wave was sent into the snowpack and received. Signal processing was then subsequently used to estimate the depth and density of each snow layer by a recursive relationship involving frequency‐modulated continuous‐wave (FMCW) radar and seismological techniques. From this method, it is also shown that the tortuosity of snow can be estimated. Data collected by gravimetric sampling was used as comparison to the SWE values determined by the use of acoustic sounding. The results showed that for the Saskatchewan sites, the correlation between the measured and the modeled values of SWE was 0·86, whereas at the British Columbia sites, the correlation was 0·78. The difference in the correlations was interpreted as being due to additional acoustic measurement error at the British Columbia sites caused by higher liquid water contents and more layers in the snowpack. The measured and the modeled SWE for Saskatchewan snowpacks with high liquid water contents were found to be weakly associated with correlations of 0·30. The acoustically‐determined values of tortuosity were close to unity (α ≈ 1), which is in agreement with the values characteristic of snow as a porous substance. Further research is necessary to determine whether this technique can be applied to snow in other environmental conditions. Copyright © 2007 John Wiley & Sons, Ltd.