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Bayesian field calibration of ocean sound maps using acoustic smart cables

S.M. Jesus(1), C. Soares(2), M. Romagosa(3) and M.A. Silva(3)
(1) LARSyS, University of Algarve, 8005-139 Faro, Portugal
(2) Marsensing Lda., Campus de Gambelas, Faro, Portugal
(3) Institute of Marine Research-IMAR & Institute of Marine Sciences-Okeanos, University of the Azores, Horta, Portugal,

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Ref.: Int. Conf. on Acoustics (ICA), Gyeongju (South Korea), October 2022

Estimating ocean noise is crucial for its impact on marine life and biodiversity. Coverage of large areas for long periods of time requires a massive modeling effort that uses shipping AIS and wind data to produce ocean sound distributions, known as sound maps. However, sound maps require matching with actual measured sound data, and eventual calibration. Field calibration strategies have been proposed and tested at small scale and in particular for coastal setups. This paper explores the possibility of using oceanic communication cables (smart cables) equipped with opportunistic acoustic receivers to calibrate sound maps at oceanic scale. The scenario is that of the CAM-ring that connects continental Portugal, Azores and Madeira archipelagos in a closed loop. Results obtained with real data on a trial in Azores and then a long range simulation in the abyssal plain between Portugal and Azores show that the proposed Bayesian sound estimator allows to optimally update the model estimate with the measured data giving an effective reduction of the expected Bayesian mean square error (BMSE). The radius of BMSE reduction is larger than the distance between smart cable repeaters (approximately 60 km), leaving a good hope for effective sound maps calibration along the cable route.