Abstract:

Modal structure is embedded in shallow water ambient noise [Kuperman and Ingenito, J. Acoust. Soc. Am. 67, 1988--1996 (1980)]. Previously, it was reported that ambient noise measurements (SWellEx-1) using a vertical array were used to extract mode shapes [Hursky, Hodgkiss, and Kuperman, J. Acoust. Soc. Am. 98, 2971(A) (1995)]. Further analysis has characterized source distributions which would support such inversions for mode shapes. Previously, it has been shown that mode shapes alone provide sufficient information to estimate source depth [E. C. Shang, J. Acoust. Soc. Am. 77, 1413--1418 (1985) and T. C. Yang, ibid. 82, 1736--1745 (1987)]. Several depth estimators based on mode shapes extracted from ambient noise were tested on towed source data (SWellEx-96). Results of processing simulated and experimental data will be presented to assess feasibility of source depth estimation without prior environmental measurements or modeling.