Acoustic sensing of large-scale ocean dynamic processes

Abstract

In recent years relationships have been established between fixed-system acoustic transmission fluctuation and ocean dynamic processes on space scales of tens and hundreds of kilometers. In this context, tide-driven processes have been studied in some detail, transport-related variations in the dynamic structure of the Gulf Stream have been studied, and investigations in progress include preliminary attempts to relate acoustic phase fluctuations on the time scale of several months to Rossby waves and/or deep-ocean eddies. These results will be reviewed, and the most recent deep-ocean experimental conclusions compared with MODE and IWEX findings. The viewpoint taken throughout is that environmental information is being extracted from a “noise background” in the sound-speed field a major component of which is the internal wave continuum. Measurement problems due to multipath effects will be discussed.