Mapping tidal current structures in Dalian Bay, China, using coastal acoustic tomography

Eleven sets of coastal acoustic tomography (CAT) systems were successfully deployed in Dalian Bay (DLB) during March 7-8, 2015, aiming to reconstruct the tidal current fields. The number of successful reciprocal transmission lines was 51, which may be the maximum number in ocean acoustic tomography history. The inverse method results showed that the velocity amplitudes in DLB were 0.75 m s(-1) near the bay mouth and 0.30 m s(-1) in the inner bay. Furthermore, the travel time difference data were also assimilated into the Finite-Volume Community Ocean Model based on the ensemble Kalman Filter method. The assimilation showed similar results to those of the inverse method. Both the inverse method and data assimilation effectively reconstructed the tidal current, with a mean root mean square difference of 0.05 ms(-1 )when compared to the Acoustic Doppler Current Profile data. Meanwhile, a tidal vortex west of Dasanshan Island was more effectively shown by assimilation rather than inversion.