A comparison of experimental and theoretical forward scattering by the Kermit-Roosevelt Seamount

The SPICEX-LOAPEX-BASSEX experiments measured forward scattering from the Kermit-Roosevelt seamounts. LFM and M-sequence signals from 250-Hz moored sources and a 75-Hz ship-deployed source were received with Penn State University’s 162-element FORA array. Receptions were obtained from these sources at ranges of hundreds to 1600 km. Previous work [J. Acoust. Soc. Am. 117, (2549)] discussed the BASSEX forward shadow and patterns of horizontal refraction around the seamount. Additional work [J. Acoust. Soc. Am. 118, (1936)] compared experimental results with theory using a conical section model of a seamount. This presentation concerns the pulse compressed and array processed time series of M-sequence signals in the forward scattered field of the seamounts. Both travel times and angles of arrival are reconciled with 2-D ray-trace models. Results are comparable to refracted rays, which mainly propagate over the seamount. These, however, do not explain additional echoes, which appear in the experiment, possibly due to reflection and/or diffraction. Normal mode and PE methods are used to confirm ray models and identify additional echoes.