Acoustical characteristics and contributions of bubbles released from melting glacier ice

Glacierized fjords present a unique acoustic environment that is significantly louder than other ice-covered environments, with average sound pressure levels of 120 dB re 1 μPa with a broad peak between 1 and 3 kHz [Pettit et al., Geophys. Res. Lett. 42, 2309–2316 (2015)]. The energy within this peak is due to the release of bubbles escaping from pressurized air-filled pores within melting glacier ice. These bubbles form during glacier formation via the compression of successive seasonal snow layers. During ice melt, the pressurized air cavities are released, jetting and squirting from the ice and into the surrounding ocean environment [Lee et al., Proc. Meetings Acoust. 20, 070004 (2014)]. In order to more sufficiently characterize this dynamic physical process, acoustic measurements and high-speed video recordings were made using melting glacier ice samples taken from LeConte Glacier in southeastern Alaska. Samples were melted and recorded in a controlled laboratory apparatus as well as at a range of de...