Acoustic Propagation Underneath the Arctic Sea-ice
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The main objective of this project is to study the effect of sea-ice on underwater acoustic wave propagation. Three main parameters define how acoustic waves react to the presence of seaice: (i) the roughness of the underside of the sea-ice, (ii) the thickness of the sea-ice, and (iii) the elastic parameters of the sea-ice determined by the material composition of the ice. To address the overall objective, field observations from the Marginal Ice Zone (MIZ) in the Fram Strait and from the Van Mijen-fjord were analysed and compared with simulations performed with the seismo-acoustic model OASES50. In the Fram Strait, long-range under-ice acoustic propagation was studied by sending communication signals (centered at 900 Hz) between two ice-tethered buoys. In this study the focus was to understand the effect of sea-ice roughness and thickness on the signal propagation. A seismic survey was conducted in the Van Mijen-fjord, providing observations for a detailed study of how low frequency acoustic and elastic waves (up to 100 Hz) interact with an ice plate. In both studies the OASES model was used for simulating the elastic wave propagation in the complex physical environments. The OASES model can be very computationally intensive for complex problems and a significant effort went into developing and implementing a parallel version of the model in order to vastly reduce the computation time.
Paper I: Hope, Gaute, Sagen, H., Storheim, E., Hobæk, H., Freitag, L., Measured and modeled acoustic propagation underneath the rough Arctic sea-ice, Journal of Acoustical Society of America 142, 3, 2017. The article is available at: http://hdl.handle.net/1956/18858Paper II: Hope, Gaute, Schmidt, H. A Parallelization of the Wavenumber Integration Acoustic Modelling Package OASES. Journal of Acoustical Society of America 144, 3, 2018. The article is not available in BORA due to publisher restrictions. The published version is available at: https://doi.org/10.1121/1.5068023Paper III: Johansen, Tor Arne, Ruud, B. O., Hope, G. Seismic on Floating Ice on Shallow Water: Observations and Modelling of Guided Wave Modes. Geophysics, in press. The article is not available in BORA due to publisher restrictions. The published version is available at: https://doi.org/10.1190/geo2018-0211.1Paper IV: Hope, Gaute, Hobæk, H., Sagen, H. Geometry of Acoustic Communication Links in the Arctic, Proceedings of the Institute of Acoustics 38, 2016. The article is available in the main thesis.Paper V: Geyer, Florian, Sagen, H., Hope, G., Babiker, M., Worcester, P. F., Identification and quantification of soundscape components in the Marginal Ice Zone, Journal of Acoustical Society of America 139, 4, 2016. The article is available at: http://hdl.handle.net/1956/18859
PublisherThe University of Bergen
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