Automated Determination of Snow Water Equivalent by Acoustic Reflectometry

Abstract—Snow water equivalent (SWE) is commonly deter-mined using gravimetric and depth measurement techniques. Pre-vious research has demonstrated the ability to determine SWE from the propagation and reflection of acoustic waves. Despite the advantages of the acoustic technique, it has not been adapted so that SWE can be determined in an automated fashion. This paper presents a new technique for determining SWE by the application of acoustics. A maximum-length sequence was used as the input to the layered snowpack system. Signal processing of the reflected wave and a recursive algorithm was used to model the sound pres-sure wave as it passed through the snowpack. Embedded systems were designed to implement the signal processing and calculations so that SWE could be quickly determined at a field location. The systems were deployed at sites near Whitehorse, YT, and at sites in the Rocky Mountains of Alberta, Canada. Comparisons were made between SWE estimated by the acoustic technique and SWE determined by gravimetric sampling. These comparisons demon-strated that the acoustic SWE measurement performed with the embedded systems and the new signal processing technique can provide SWE estimates that are of comparable accuracy to SWE calculated from gravimetric samples. Index Terms—Acoustic devices, acoustic propagation, acoustics, acoustic signal processing, snow. I