2019_programme: SEA-SURFACE SCATTERING OF A CONTINUOUS WAVE IN THE 1 TO 200 HZ FREQUENCY RANGE



  • Session: 17. Modeling techniques for underwater acoustic scattering and propagation
    Organiser(s): Gunderson Aaron, Isakson Marcia
  • Lecture: SEA-SURFACE SCATTERING OF A CONTINUOUS WAVE IN THE 1 TO 200 HZ FREQUENCY RANGE
    Paper ID: 775
    Author(s): Bennaceur Iannis, Cristol Xavier
    Presenter: Bennaceur Iannis
    Presentation type: oral
    Abstract: The purpose of this paper is the scattering of a continuous wave in the 1 to 200 Hz low frequency range by the fully developed swell of the Atlantic Ocean in a deep-water configuration. Considering the scales of the problem, we use the small-perturbation method coupled with the normal-mode theory and an asymptotic analysis to derive the first order spatio-temporal scattered pressure field p1. This approach, greatly inspired by Labianca and Harper, allows us to express p1 depending on the normal-mode functions and their associated wave-numbers that we compute numerically using an in-house modal propagation code called MOCTESUMA. This code may be run for an ocean waveguide with any particular sound-speed profile and takes into account the propagation into multiple-layers sea-bottom. First, we compare the computed power spectral density of pressure fluctuations with the one measured experimentally in the Sargasso Sea [1]. In a second phase we compare the propagation losses undergone by the scattered field and the non-perturbed field in the shadow zone appearing when the acoustic source is located in the summer thermocline. Finally we look at the level of scattered energy on both sides of the scattering mechanism cut-off ratio Γ/k0=2, depending on the source immersion.
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  • Corresponding author: Dr Bennaceur Iannis
    Affiliation: THALES Defense Mission Systems FRANCE
    Country: France
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