Passive tomography in coastal areas: A feasibility study of the Ushant front monitoring

This work presents a feasibility test of acoustic data assimilation in a basic feature model of the Ushant front, west off Brittany, enabling the tracking of the principal characteristics of the front. Two monitoring applications are presented for tracking the tidal variations of the front and its seasonal variations (from April to July). The data assimilation method is based on ensemble Kalman filtering, enabling the process of the nonlinearity between front parameters and acoustic measurements. To prevent from the resolvability problem inherent to travel-time tomography method in shallow water, the proposed scheme considers full-field acoustic data and a normal-mode propagation model taking into account the seabottom properties. The complex field on a vertical array of receivers is assimilated in the front model to continuously correct the prediction of the front parameters. Simulation results demonstrate the feasibility of the method.