Range-dependent modal eigenvalue estimation in the SWAT experiment

Abstract

Three modal mapping experiments (MOMAX) have been conducted in shallow water environments: two in the East coast STRATAFORM site off the New Jersey coast; and one in the Gulf of Mexico off the Florida coast. A low-frequency source emits a set of CW signals in the range 20–500 Hz, and the field is measured by drifting buoys. The ultimate goal of these experiments is to invert the acoustic field data in water for the sound speed profile in the seabed. The analysis has focused on measuring the modal characteristic wavenumbers (eigenvalues) as a function of position. In general, one has to resort to range-dependent spectral analysis. Techniques based on both the short-term Fourier transform and high-resolution parametric spectrum estimation have been used for measuring eigenvalues. New results from the year 2000 SWAT (MOMAX III) experiment at the STRATAFORM site will be discussed. These include a comparison of data obtained from tracks along and across the New Jersey shelf. [Work supported by ONR and WHOI Academic Programs Office.]