Now casting Anthropogenic Ocean Noise in High Pressure Areas

International audienceIn order to address the issue of ambient noise monitoring under the Marine Strategy Framework Directive, a global anthropogenic noise prediction system called Quonops© has been designed similarly to meteorological forecasting systems. Quonops© combines real-time environmental data and real-time human information and assimilates real-time acoustic measurements to produce the resulting 3D ocean noise fields as a function of time. The system has been thought to cover most basins and activities. The French Hydrographic Office and ENSTA Bretagne have conducted a monitoring experiment in the West-end of the British Channel in the vicinity of the Ushant traffic separation scheme. Two hydrophones were deployed at about mid-depth, one at the border of the south-going route, another 10NM off the same route. It has been observed that even with high noise levels, the measure is likely to be affected by local events, inducing up to 30dB dynamics at the scale of hours. Quonops© has been implemented to now-cast the low frequency noise in the same area. The comparison at the hydrophone locations of the prediction and measurement has shown good agreement, predicting in particular the statistical and stochastic content of the ambient noise in such a high pressure area