JONAS - Joint Framework for Ocean Noise in the Atlantic Seas

D5.3 - Standards for the calibration of acoustic modeling

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Ref.: JONAS Deliverable 5.3, February 2022

Executive summary:
Jonas will develop and pilot a noise-monitoring platform, harmonize technical approaches to MSFD requirements, and promote the adoption of quieter operational practices among users of the NE Atlantic marine space. This effort will essentially be based on extensive computer modeling using AIS and archival environmental data to achieve the necessary coverage for the wide Atlantic area. Although the collection of actual field data is not foreseen during the project itself, devising methods for calibrating model output to better represent the reality is an absolute requirement. That is why work package 5 deals with methodologies for computing noise maps and encompasses a task dedicated to model calibration through ground truth acoustic measurements, under which this work was performed. Ground truth calibration, here after "field calibration", represents a challenge for at least two main reasons: one, is that the number of field observations are in all circumstances too few for efficiently constrain the modeled field in large areas and during long periods of time, and second, there is no known way to validate the calibrated field in a way to direct the calibration effort. In practice, there is no well accepted methodology for field calibration and/or for data sampling strategy. Efforts in that direction in previous EU projects such as BIAS and JOMOPANS provided data model comparisons but no definite calibration strategies, entailing model modification to approach the observed data. This report summarizes the work performed under the task dedicated to field calibration where the problem is analyzed by describing previously proposed techniques and a number of possible future approaches with their advantages and drawbacks are outlined. One of those approaches to our knowledge, not previously tested on real data, was implemented in a data set kindly provided to JONAS by the IMAR Okeanos group of the Azores University, with interesting results. Data - model comparisons is then performed through objective distribution distance indicators and tested in another data set gathered in the southwest approaches to the channel, off Bretagne. Future developments will encompass the usage of this and other field calibration techniques for computing broadband continuous noise and cetaceans impact indicators. Journal and conference publications of this work are being submitted.