Toward monitoring submarine glacier melt using hydroacoustics: The role of timescale in the signal of bubble release

Submarine glacier melt plays a key role in determining glacier stability and driving glacier mass loss. However, quantifying submarine melt remains challenging due to occupational hazards near glacier termini. One method that has been proposed as a low-cost long-term option for remote sensing, though remains unproven, is to use the sounds of glacier ice bubbles to study submarine melt from afar. Calculating melt rate from bubble acoustics remains complicated because different bubbles produce acoustic energy heterogeneously. This study investigates the physical factors that cause this heterogeneity. A computational method to determine time scales of acoustical excitation and acoustic energy values is proposed and utilized to analyze 203 bubble release events from glacier ice collected in Svalbard, Norway. The distributions of these variables are used to show the existence of two separate types of bubble release events. Additionally, internal pressures are determined for the subset of events with the highest acoustic energy values. No straightforward relationship between time scale of excitation and internal pressure is found. This work begins to untangle the acoustic signal of submarine glacier melt and necessitates further research into the environmental factors modulating bubble release.