MODEL BENCHMARKING RESULTS FOR SHIP NOISE IN SHALLOW WATER Bas Binnerts a , Christ de Jong a , Ilkka Karasalo b , Martin Östberg b , Thomas Folegot c , Dominique Clorennec c , Michael A. Ainslie d1 , Graham Warner d2 , Lian Wang e a TNO – P.O. Box 96864, NL-2509 JG The Hague b FOI – Gullfossgatan 6, SE-16490 Stockholm c Quiet-Oceans – 525 av Alexis de Rochon, Plouzane, France d1 JASCO Applied Sciences – Mergenthaler Allee 15-21, 65760 Eschborn, Germany d2 JASCO Applied Sciences – 2305-4464 Markham St, Victoria BC, V8Z 7X8, Canada e NPL – Hampton Road, Teddington, TW11 0LW, UK Bas Binnerts, TNO - P.O. Box 96864, NL-2509 JG The Hague, bas.binnerts@tno.nl Abstract: To support North Sea countries to comply with EU legislation, a framework for a fully operational joint monitoring programme for ambient noise in the North Sea is developed in the Interreg Joint Monitoring Programme for Ambient Noise North Sea (JOMOPANS). A key task in the project is to develop and demonstrate verified and validated modelling methods applicable for generating maps of ambient noise in the North Sea, with a focus on ships and wind as the dominant sources of sound. Within the project a wide range of acoustic propagation model implementations from the JOMOPANS project partners are verified by means of a comparison of the output for two well-defined benchmark scenarios based on the modelling scenarios developed for the Weston Memorial Workshop. The model types considered are based on energy-flux integration, analytical and numerical mode solvers, parabolic equation range step integration, ray tracking and wavenumber integration. Recommendations on the use of these models are given and limitations are discussed. The acoustic metric considered is the depth-averaged sound pressure level in one-third octave (base 10) bands from 10 Hz to 20 kHz. The results show that the majority of the tested models are in agreement for a range- independent shallow water environment, providing a reliable benchmark solution for the future verification of other propagation models. The observed agreement gives confidence that these models are correctly configured and able to provide numerically correct solutions. For a range-dependent environment however, a significant uncertainty remains. The solutions provided in this paper can be used as a reference to select the optimal compromise between reducing the computational complexity and increasing the model precision for the propagation of sound in shallow water. Keywords: Underwater acoustics, Propagation modelling, benchmarking scenarios, model verification, Ambient noise, JOMOPANS project