• Session: 14. Environmental acoustics and noise
    Organiser(s): Barclay David
  • Lecture: SHIP NOISE MAPPING IN UK WATERS [invited]
    Paper ID: 938
    Author(s): Farcas Adrian, Powell Claire, Culloch Ross, Merchant Nathan
    Presenter: Farcas Adrian
    Presentation type: oral
    Abstract: Maps of underwater noise levels are needed to assess the risk of impact to marine fauna and inform management measures. Noise maps are based on modelled source levels and the acoustic propagation characteristics of the environment. However, for shipping noise, modelling the large numbers of sources using numerical models is computationally intensive, and current sound mapping approaches have not been rigorously validated with experimental data. Here, we present a computationally efficient approach for producing instantaneous shipping noise maps of large spatial areas at high temporal resolution, and assess the predictions against field measurements. Satellite Automated Identification System (sAIS) ship-tracking data was used to produce noise maps based on the position of each tracked vessel at 10-minute intervals. The propagation losses were pre-computed on a 5-km resolution grid using an energy flux method, taking into account bathymetry, seabed properties, and variations in the water column properties for each calendar month. An ensemble model for ship source level was combined with the propagation loss matrices to produce maps of the shipping noise component. Additionally, the contribution of wind-driven noise was computed, allowing the exceedance of shipping noise above this natural background to be assessed. Combined noise maps of UK waters shelf were produced covering the year 2017 at 10-minute intervals. The results were validated against measurements taken at monitoring stations along the east coast of Scotland during 2017, as part of the Marine Scotland East Coast Marine Mammal Acoustic Study (ECOMMAS). Overall, the model predictions of the median sound level were within ±3 dB for 91% of the data for frequency bands in the range 125 Hz – 2 kHz, indicating significant confidence in the model predictions. We also discuss ongoing work to improve the efficiency of the model for marine spatial planning applications.
  • Corresponding author: Dr Farcas Adrian
    Affiliation: Centre for Environment, Fisheries & Aquaculture Science (Cefas)
    Country: United Kingdom