2019_programme: SOUNDSCAPE CONTRIBUTIONS OF GLACIER ICE BLOCKS – INSIGHTS FROM LABORATORY MEASUREMENTS

• Session: 09. Acoustics in polar environments
  Organiser(s): Tegowski Jaroslaw
• Lecture: SOUNDSCAPE CONTRIBUTIONS OF GLACIER ICE BLOCKS – INSIGHTS FROM LABORATORY MEASUREMENTS [invited]
  Paper ID: 957
  Author(s): Blondel Philippe, Tegowski Jaroslaw, Deane Grant
  Presenter: Blondel Philippe
  Presentation type: oral
  Abstract: Acoustic measurements in Arctic fjords and next to marine-terminating glaciers show important contributions from glacier melting, and individual icebergs or growlers. As they melt, they release high-pressure gases and produce sounds at medium to high frequencies. Associated to fields of hundreds or thousands of melting growlers and ice blocks, they add significantly to the soundscape. A summer 2009 survey of Murchison Fjord (Svalbard) by Tegowski et al. (2010) show these contributions can, even in extremely calm weather (Sea State 0), be as loud as Sea State 4. \nTo isolate individual contributions, a series of laboratory experiments have been conducted. In 2012, growlers collected in Svalbard and stored on R/V Horyzont II were measured in an anechoic tank at the Technical University of Gdansk in a variety of configurations, individually and in groups of colliding and scraping icebergs. A field survey in Svalbard, in summer 2014, was used to collect another series of growlers of different sizes, aspects (e.g. bubble contents, ice colours) and morphologies (from rough to rounder and partially melted). Tank measurements in an ad hoc tank at the Polish Polar Station investigated the full melting of these growlers. Both sets of experiments used similar setups, with high-sensitivity broadband hydrophones and high frequency (96 kHz) data acquisition. The acoustic pressures and energies radiated over the lifetime of the growlers were measured by 0.1-second segments. Relative levels of individual transients and evolution over the lifetimes of the individual growlers, in different configurations and with different melting rates, have been measured. These two sets of measurements can then be related to large fields of melting ice blocks, and compared to field measurements, quantifying the soundscape contributions at different frequency bands, and offering insights into ice dynamics and local conditions.\n
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• Corresponding author: Dr Blondel Philippe
  Affiliation: University of Bath
  Country: United Kingdom
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