Broadband frequency response modeling for inversion of a shallow‐water waveguide with a range‐dependent soft clay bottom (Yellow Shark ’95 experiment).

During the Yellow Shark ’95 experiment the broadband frequency response (200–800 Hz) of a shallow‐water waveguide was measured for the purposes of performing multimodal inversion of its acoustic and geoacoustic properties. Measurements from vertical receiving arrays deployed every 8 km along a 40‐km tomography transect showed that the frequency response was mostly flat with high transmission loss at selected frequencies. This differs from often observed frequency dependence in other shallow‐water environments where there is some low frequency with minimum loss, suggesting an optimum frequency of propagation. Range‐dependent geoacoustic and seismic data along the transect and water sound‐speed data measured during the acoustic transmissions permitted the development of a realistic environmental model. Normal‐mode modeling results with C‐SNAP indicated that the presence of a soft clay top layer with a speed less than the water column was a decisive factor in the observed frequency dependence, since it acted...