Global shipping soundscapes: A study of the COVID-19 impact

The global ocean soundscape, at frequencies below 400 Hz, is dominated by shipping and at some select frequencies marine mammals and large storms. In this paper, we present a global model of the shipping and wind noise soundscape. The Parabolic Equation (PE) Model is used to compute the propagation loss from a grid of points through the dynamical ocean to a high resolution grid of receivers. Source depths of 5 m are used for ships and 1/4 wavelength are used surface wind. The combined wind/shipping soundscape can then be generated using satellite observations of the shipping positions via Automated Identification Services and the wind speed at 10 m. Both databases were provided by SPIRE Inc. SPIRE provided the shipping AIS for March/April 2018 and March/April 2020. The global shipping soundscape for these two time periods reveals a drop of 3-6 dB depending upon position at 50 Hz from the reduction in surface shipping traffic due to the COVID-19 global shut down.