Snow cover effects on acoustic sensors

Abstract

Measurements were conducted to determine the effect of a snow cover on acoustic wave propagation during a 50 day period in Alaska. Acoustic waveforms produced by a blank pistol shot were recorded after propagating horizontally over various snow-covered propagation paths and were used to determine the snow cover parameters by comparison with theoretically calculated waveforms. This automatic comparison procedure was successful in determining the average snow cover permeability and depth even when the snow cover depth varied greatly across the propagation path. Although the snow cover properties remained relatively constant during the measurement period, the acoustic measurements were able to determine the changes caused by wind events and new snowfall. Acoustic measurements can provide a rapid, accurate method for determining and monitoring snow cover characteristics. The excess attenuation produced by the snow cover was generally about − 30 dB for 100 m distance and frequencies above 100 Hz. Theoretical calculations also show that even a thin snow cover only 0.02 m thick will affect acoustic pulse propagation. The attenuation and distortion caused by a snow cover can degrade passive acoustic sensor identification and distance estimation, but these detrimental effects can be mitigated by proper design of signal processing algorithms.