2023_programme: Towards estimating water column properties using ambient noise interferometry in the deep ocean

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  • Session: 10. Observing the Oceans Acoustically
    Organiser(s): Bruce Howe and Kai Gemba
  • Lecture: Towards estimating water column properties using ambient noise interferometry in the deep ocean
    Paper ID: 2029
    Author(s): Ragland John, Abadi Shima
    Presenter: Ragland John
    Abstract: The cross-correlation of stochastic ambient noise between two sensors can, under the right conditions, converge to an estimate of the Green’s function between the two sensors. This passively estimated Green’s function is referred to as the empirical Green’s function. The Ocean Observatories Initiative (OOI) has 11 hydrophones that constantly record ambient sound in the ocean and makes the data publicly available. This observatory provides an opportunity to investigate ambient noise interferometry in the deep ocean. In this paper, two OOI bottom mounted hydrophones in the north-east Pacific, separated by 3.2 km and located at a depth of 1500 m are used to investigate the possibility of using passively estimated multi-path acoustic arrivals for measuring water column properties. Previous work has shown that the empirical Green’s function between these hydrophones reliably contain peaks that correspond to multiple acoustic propagation paths throughout six years of analyzed data. These peaks have the potential to be used for estimating information about the water column, such as sound speed or temperature. In this paper, the empirical Green’s functions calculated for these two hydrophones will be used to estimate multi-path arrival times between the two hydrophones. Additionally, the accuracy of these arrival times will be quantified. The passively estimated arrival times will then be compared to simulated arrival times. Using acoustic simulations, the effects of sound speed fluctuation, changing hydrophone geometry, and tides will be investigated and compared to the passively estimated arrival times. Lastly, a discussion of the implications for estimating water column properties using ambient sound at this specific location, and more generally for deep ocean hydrophones will be presented. [work supported by ONR]
      Download the full paper
  • Corresponding author: Mr John Ragland
    Affiliation: University of Washington
    Country: United States
    e-mail:

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