2023_programme: An operational coupled-mode model for shipping-noise prediction

• Session: 20. Underwater noise in the EU Marine Strategy Framework Directive: monitoring and impacts on marine ecosystems
  Organiser(s): Jakob Tougaard, Aristides Prospathopoulos and Emmanuel Skarsoulis
• Lecture: An operational coupled-mode model for shipping-noise prediction
  Paper ID: 2013
  Author(s): Skarsoulis Emmanuel, Piperakis George, Prospathopoulos Aristides Makropoulos Dimitris, Cadudal Louise Iellatchitch François
  Presenter: Skarsoulis Emmanuel
  Abstract: A prediction model for shipping noise in range-dependent environments based on coupled-mode theory is presented, as an enhancement to existing adiabatic normal-mode approaches. Emphasis is put on the categorization of environmental changes and precalculation and storage of eigenvalues, eigenfunctions and coupling matrices, such that they can be looked up and restored to efficiently compute the acoustic field of arbitrary noise source distributions over a given sea area. The proposed approach involves discretization of the bathymetry with a certain resolution, and clustering of areas with similar geoacoustic characteristics and sound-velocity profiles, the latter on a seasonal, e.g. monthly, basis, resulting in a group of local environments for which the vertical problem is solved. Taking into account that the water depth is the main factor determining the number of propagating modes for a particular frequency, coupling is applied only in the case of changing bathymetry, whereas changes in the water sound-speed profile and/or the geoacoustic characteristics are treated adiabatically. In this connection, coupling matrices are calculated only between environments of the same type (sound-speed profile and geoacoustic characteristics) and subsequent water depths, which significantly reduces the computational burden and storage requirements. For the calculation of the noise field in areas with abrupt depth changes, additional nodes are introduced such as to obtain range segments of subsequent discrete depths for which coupling matrices are available. Examples of noise calculations are given for benchmark setups in the Eastern Mediterranean Sea.\n
• Corresponding author: Dr Emmanuel Skarsoulis
  Affiliation: Institute of Applied and Computational Mathematics, Foundation for Research and Technology Hellas
  Country: Greece
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