Rapid determination of seafloor acoustic reflectivity by exploiting frequency variability within striations data

For shallow oceans, multi-path interference generates a pattern of striations when broadband data received on a single hydrophone are viewed on a range-frequency display. The frequency variations within this data are known to be related to the ocean depth, and to the seafloor acoustic reflectivity. A simple process has been developed by which the frequency spacing of the striations data may be extracted, and the reflectivity determined by inversion, using data obtained from an incoherent source such as a ship-of-opportunity. The technique is demonstrated both by simulations, and using ship-generated data obtained in shallow water off Perth, Western Australia. The seafloor reflectivity values derived from application of the technique are used in predictions of transmission loss which are compared with measured transmission losses, and with transmission losses predicted using seafloor descriptions based on bottom grab samples.