Stability and identification of ocean acoustic multipaths

A phase-coded signal with 64-ms resolution was transmitted at 10-min intervals for a 48-day period between an acoustic source moored at 2000-m depth and a bottom mounted receiver at ∠3000-m depth and at ∠900-km range. About 16 multipaths were resolved. They were stable in the presence of ocean fluctuations and could be identified (with some exceptions) from ray theory. The precision to which daily travel-time fluctuations along multipaths could be measured was better than 10 ms. The resolution, stability, identification, and precision is adequate for acoustic monitoring of mesoscale ocean variability by measuring travel-time variations along ray paths.