Abstract:

The stabilities and instabilities of acoustic multipaths have been studied over basin scales as part of the development of studying climatic temperature changes in the ocean. In 1983, such transmissions began from the Kaneohe source where the propagation was complicated by the interaction of sound with the bottom near Oahu, Hawaii. For years, these transmissions exhibited stable arrivals only for those multipaths that were quite steep at the axis of the sound channel, for example, about 15 deg. Models indicate that the steeper multipaths may form ``bounded-chaotic seas'' that are useful for thermometric studies because their upper turning depths are insensitive to fluctuations. The sensitive nature of these paths is a consequence of the interactions with the bottom and the long distance of propagation, i.e., 3709 km. The flatter multipaths could not be used for inferring temperature variations because they were unstable. It is now understood that these paths are sensitive to fine and meso-scales which vertically scatter the energy over a kilometer, the same scale as the waveguide. [Work supported by ONR.]