Spatial mapping of underwater noise radiated from passing vessels using automatic identification system data

Abstract

Information regarding the spatial distribution of noise radiated by ships in specific areas is used as basic data for the protection of marine organisms and establishment of marine spatial planning. This study derived the spatial distribution of the noise radiated from ships navigating the southern region of Korea by acoustic modeling using Automatic Identification System data. The acoustic energy propagated from a ship to all spatial points in the experimental area was modeled using a ray-based model, and the noise level at a particular point was incoherently summed over all spatial points and averaged over time. By applying the acoustic modeling technique, we derived the average noise level at frequencies below 1 kHz radiated from ships in the ocean, and compared it with the acoustic data measured during the same period. Discrepancy between both results was found at frequencies below 250 Hz, and the possible cause of this discrepancy is related to the power-law model used to calculate the source level of the ship based on an empirical formula. The difference in current can be reliably reduced by applying a more accurate ship source model.