Ray identification and ranging issues in deep water

Abstract

Ocean acoustic positioning systems require accurate measurements of travel time from several acoustic beacons. When receiver position is unknown, the uncertainties in the sound speed, source position, currents, internal waves, and tides must be addressed and bounded. High travel time accuracy has been achieved in the deep ocean in ocean acoustic tomography experiments via a combination of long-duration acoustic arrival time-series, accurate source/receiver positioning, and comprehensive, post-experiment ocean modeling and data assimilation. For offline autonomous underwater positioning, those are not available. Strategies to reduce acoustic forward model uncertainties and improve acoustic ranging in deep water will be discussed.