ASA 127th Meeting M.I.T. 1994 June 6-10

3pUW5. Structures and intensities of interference zones in a ducting shallow water environment.

Donald R. Del Balzo

Carlo Ferla

SACLANT Undersea Res. Ctr., Viale San Bartolomeo, 400, 19138 La Spezia, Italy

Observations of regularly spaced zones with high propagation loss in a shallow water ducting environment were reported at the Denver ASA meeting [D. Del Balzo, J. Acoust. Soc. Am. 93, 1886(A) (1993)]. These zones resulted from interference between a small number of acoustic modes from a low-bandwidth (5-Hz) signal centered at 342.5 Hz. The current work is a modeling effort to describe the zonal structures and to determine their sensitivity to various factors; e.g., duct size and strength, source depth, center frequency, and bandwidth. Narrow-band and broadband normal mode calculations are employed to ascertain the physical size, location, and intensity of the zonal features.