Clustering Sound Speed Profiles in East China Sea

SSP cluster analysis was performed in the region with water depth in the range 75 m ~ 150 m in ECS. By assuming that the water density stratification follows that of the - coordinate, and that the continental shelf region in ECS was a relatively flat one, the SSPs in this region were clustered with the -coordinate. Principle Component Analysis (PCA) method and the Self-Organizing Map (SOM) method were employed to cluster the SSPs calculated from the outputs of the regional FVCOM model. Results suggest the region north of Taiwan fluctuates most and that the region corresponding to each group stretches along the contour line, which agrees with the current system there. Acoustic propagation analysis show that acoustic propagation in different groups show different sensitivities to SSP fluctuation and the source depth could make a difference. The reason lies in the fact that amplitudes for the propagating modes would be excited in different degrees for different source depth so that effect of SSP fluctuation differs greatly.