Range‐dependent acoustic propagation in a channel with ocean variability: A comparison of observations and modeled results

The skewness of the distribution of acoustic intensities due to multiple scattering [T. E. Ewart, J. Acoust. Soc. Am. 84, 1490–1498 (1989)] and the possible obliteration of fine detail diffraction effects by random phase modulation indicate that it may never be appropriate to decouple variability from calculations of a mean acoustic field. If so, this has serious implications for the (often used) approach of adding on (or even ignoring) variability to the mean‐field results of deterministic modeling. In October 1989, an experiment was conducted in the North Sea by SACLANTCEN, Italy in collaboration with FWG, Germany to simultaneously observe the acoustic field and oceanographic condition in a weak acoustic surface channel. The channel exhibited volume variability and appreciable surface roughness. A 50‐m depth source was towed away from a stationary 62‐m vertical array, transmitting 40‐ms cw pulses at 800, 1000, and 1500 Hz. Measurements were taken out to a range of 35 km and back. A simultaneous oceanogr...