Abstract:
The ocean acoustic forecasting system combined the wave-tide-circulation coupled ocean model developed by First Institute of Oceanography, MNR (FIO-COM) with several underwater sound propagation models(Yang et al, 2023). In this paper, the system is further developed to identify and predict the position and evolution of ocean mesoscale structures by utilizing abnormal data of sea surface height. It also generates corresponding acoustic parameters that accurately characterize the mesoscale structures. The acoustic propagation effects in diverse and complex marine environments were studied and analyzed, taking into account the presence of mesoscale structures such as the Okinawa Trough, the Kuroshio Front, and the North Pacific Cold Eddy. The results indicate that, compared to the changes in the structure of the sound velocity profile, the influence of trough topography on sound propagation is more significant. When a sound source located outside the trough propagates through it, most of the sound energy becomes trapped at the bottom of the trough, making it difficult for it to reach the opposite side; without considering the influence of topography, the elevated sea surface temperature associated with the Kuroshio front results in weakened sound energy near the sea surface. This, in turn, leads to an increase of approximately 5-10 dB in sound propagation loss compared to a range-independent water environment; the presence of a cold eddy can cause sound energy to converge earlier, thereby altering the width, intensity, and location of the convergence zone.