SAS2: the system for acoustic sensing of snow

Abstract

Abstract: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 and more 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 Canadian Rockies. Stationary and portable versions of the system were deployed and tested. This paper reports initial tests of the SAS2 that were conducted at the field sites to compare acoustic model outputs with gravimetric measurements 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. Unlike monopulse sonar and radar sensors, the SAS2 utilizes a continuous-wave Maximum Length 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.

Observations of capillary barriers and preferential flow in layered snow during cold laboratory experiments

“…The absolute difference spans 0.8 and 2.97 vol %, thus it is consistent with the literature (Kinar and Pomeroy, 2015). Measured and simulated LWC by SNOWPACK are also in fair agreement (see previous section) which underlines the above mentioned range of absolute error, since SNOWPACK bases an energy conservation on mass.…”

“…Increasing the spatial resolution of LWC measurements is challenging as measuring LWC in snow is still marked by high uncertainties (Colbeck, 1978;Fierz and Föhn, 1995;Avanzi et al, 2014). It is only recently that undisturbed, non-destructive, and repetitive measurements of LWC have been obtained (Heilig et al, 2010Schmid et al, 2015;Kinar and Pomeroy, 2015). A promising alternative might be given by pore-scale measurements of liquid water flow (Adachi et al, 2012;Walter et al, 2013).…”

“…Melting calorimetry has been widely used to measure LWC for decades (Yosida, 1960), but Colbeck (1978) points out that this method may be inaccurate as it implies the calculation of a difference between large numbers (Stein et al, 1997). According to Kinar and Pomeroy (2015), absolute errors in measuring LWC using calorimetry span 1 and 5 %. The instrument we used here (the so-called Endo-type snowwater content meter) was proposed by Kawashima et al (1998).…”

“…Finally, a highly fingered flow may be missed and/or disturbed by using larger instruments (Stein et al, 1997). For future experiments, we will also consider alternative portable techniques, such as a dilution method (Davis et al, 1985;Kinar and Pomeroy, 2015;Mitterer, 2016).…”

Experimental measurements for improved understanding and simulation of snowmelt events in the Western Tatra Mountains

“…Snow wetness is not commonly measured in snow hydrology research although several recent papers presented the development of some new devices and modeling of liquid water content of snowpack (Avanzi et al, 2014(Avanzi et al, , 2015. Examples of other new devices are Heilig et al (2015), or Kinar and Pomeroy (2015), while Hirashima et al (2014) or Wever et al (2014) discuss the new modeling methods. In this study we have used the Snow Fork in snow pits.…”