Transmission-time variability, vertical spatial and temporal analysis of NAPOLI'85, an experiment in the Tyrrhenian Sea
An acoustic propagation experiment (NAPOLI '85) was carried out in the Tyrrhenian Sea in October 1985 in which signals from a broadband source were recorded at a range of 5 km with a vertical 62-m hydrophone array over a period of five days. The experiment was designed to investigate the transfer function of the ocean medium over an acoustic frequency range from 250 Hz to 2 kHz as a function of time and position down the vertical array. This memorandum describes the experiment and treatsthe pulse arrival times for one ray path, the lower refracted path. In contrast to most previous experiments of this type, the sound-speed refractive index variability was dominated by non-internal-wave features. Some of the implications of this (regarding input to the scattering theory and acquiring environmental measurements) are explored. The experimental spatial structure function of the arrival time down the vertical array is presented and shown to compare well, given the limitations of the data, with theoretical predictions both as regards its magnitude and functional behaviour.
Potter, John Robert;
Uscinski, B. J.