Kaneohe acoustic thermometer further validated with rays over 3700 km and the demise of the idea of axially trapped energy

The Kaneohe acoustic source transmitted 133-Hz, 60-ms resolution signals over 3709 km from Oahu at 183-m depth to a Naval receiver at 1433-m depth near northern California. Ray theory successfully models the acoustic multipaths whose travel times are unambiguously tracked between 1983-89, despite the fact that the sound bounces one or more times from the Oahu slope before becoming trapped in the sound channel. The eigenrays are inclined at about 15 degrees at the axis of the sound channel. The upper turning depths of the eigenrays are insensitive to realistic perturbations along the section. This supports the finding that the changes in delay of similar to+/-0.2 s between 1983-89 are due to temperature and not due to changes in the multipaths. Compared with transmission through a smoothed representation of the ocean's acoustic waveguide, the mesoscale and submesoscale features vertically scatter axially trapped energy about 200 and 800 m, respectively. The submesoscale structure may be associated with internal waves. Scattering from a combination of the meso and submesoscale is not a perturbation since scattering redistributes sound that would be otherwise axially trapped over 1 km; the scale of the acoustic waveguide. (C) 1996 Acoustical Society of America.