Deep ocean sound speed characteristics passively derived from the ambient acoustic noise field

Deep ocean sound speed characteristics passively derived from the ambient acoustic noise field

Evers, L.G. (TU Delft Applied Geophysics and Petrophysics; Royal Netherlands Meteorological Institute (KNMI))
Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)
Heaney, KD (Ocean Acoustical Services and Instrumentation Systems)
Snellen, M. (TU Delft Aircraft Noise and Climate Effects)

2017

The propagation of acoustic waves in the ocean strongly depends on the temperature. Lowfrequency acoustic waves can penetrate the ocean down to depths where few in situ measurements are available. It is therefore attractive to obtain a measure of the deep ocean temperature from acoustic waves. The latter is especially true if the ambient acoustic noise field can be used instead of deterministic transient signals. In this study the acoustic velocity, and hence the temperature, is derived in an interferometric approach from hydrophone array recordings. The arrays were separated by over 125 km, near Ascension Island in the Atlantic Ocean, at a depth of 850 m. Furthermore, the dispersive characteristics of the deep ocean sound channel are resolved based on the retrieved lag times for different modes. In addition, it is shown how the resolution of the interferometric approach can be increased by cross correlating array beams rather than recordings from single-sensor pairs. The observed acoustic lag times between the arrays corresponds well to modelled values, based on full-wave modelling through best-known oceanic models.

Atlantic Ocean
Interferometry
Acoustic properties
Wave propagation

http://resolver.tudelft.nl/uuid:5bf1b74f-1582-40e0-bdc3-9ec696cdb67d

https://doi.org/10.1093/gji/ggx061

0956-540X

Geophysical Journal International, 210, 27-33

Institutional Repository

journal article

© 2017 L.G. Evers, C.P.A. Wapenaar, KD Heaney, M. Snellen