Ship sound mapping in the North Sea

There is an increasing concern that anthropogenic underwater noise may have a negative impact on marine life. Governmental authorities are introducing regulations to address this problem. The European Commission, for instance, has adopted the Marine Strategy Framework Directive requiring EU Member States to achieve or maintain Good Environmental Status, regarding underwater noise amongst other forms of pollution. A task group (the technical sub-group on underwater noise) has formulated indicators for underwater noise pollution, resulting in an advice to monitor low frequency sound in particular frequency bands (sound pressure level in the third-octave bands centred at 63 Hz and 125 Hz). Model generated sound maps were identified as a monitoring tool to complement measurements. Recently, the SONIC (Suppression Of underwater Noise Induced by Cavitation) project was awarded within the European Seventh Framework Program to develop tools to investigate and mitigate the effects of underwater noise generated by shipping activities. In this paper, we will present the SONIC approach to generate shipping sound maps. The sound map generation tool uses Automatic Identification System (AIS) as well as biological distribution data to generate maps representative of the sound exposure that marine mammals and fish would experience. This tool uses a fast acoustic model developed specifically for this purpose that was compared to normal modes and parabolic equation models. Results of the models compared with reference models are presented in this paper