Donald R. Del Balzo
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.