SAS2: the system for acoustic sensing of snow

A novel electronic sensing system (SAS2) was designed to non-invasively and simultaneously measure snow density, liquid water content, and temperature of snow using acoustics and obtain images of the snowpack. The system is an updated andmore sophisticated version of previous acoustic sensing systems, and this paper presents an update on the development of acoustic sensing methods to measure multiple snowpack properties and obtain images of snowpack stratigraphy. Air-coupled acoustic waves were sent into and reflected from the snowpack by the SAS2 system. An inverse model based on a modified version of the Biot–Stoll theory of sound propagation through porous media was used to obtain acoustic measurements of snow and images of the snowpack. The SAS2 was deployed at ten field sites in the CanadianRockies. Stationary and portable versions of the systemwere deployed and tested. This paper reports initial tests of the SAS2 thatwere conducted at thefield sites to compare acousticmodel outputswith gravimetricmeasurements of snow density, dielectric measurements of liquid water content, and thermocouple and thermometer measurements of snow temperature. Snow water equivalent could be estimated more accurately and quickly with the SAS2 than with an ESC30 gravimetric snow tube. Unlikemonopulse sonar and radar sensors, the SAS2 utilizes a continuous-waveMaximumLength Sequence (MLS) that is more robust to environmental noise. The SAS2 serves as a proof-of-concept of the acoustic snow measurement technique with potential for further research as identified and discussed in this paper. Copyright © 2015 John Wiley & Sons, Ltd.