Long-term noise interferometry analysis in the northeast Pacific Ocean

Area of Science:

• Ocean Acoustics
• Seismology
• Marine Bioacoustics

Background:

• Ocean Observatories Initiative Cabled Array provides long-term acoustic data.
• Deep-ocean ambient noise interferometry is an emerging technique.
• Understanding sound propagation and marine mammal vocalizations is crucial.

Purpose of the Study:

• To analyze six years of ambient noise data from two deep-ocean hydrophones.
• To demonstrate the capability of ambient noise interferometry for detecting multi-path arrivals.
• To assess long-term trends in acoustic signal characteristics and monitor fin whale chorus.

Main Methods:

• Utilized six years of continuous data from two Ocean Observatories Initiative Cabled Array hydrophones.
• Employed ambient noise interferometry techniques to analyze acoustic signals.
• Analyzed multi-path arrival peak emergence and signal-to-noise ratio trends.

Main Results:

• Successfully demonstrated reliable detection of multi-path arrivals in the deep ocean using bottom-mounted hydrophones.
• Observed long-term trends in the signal-to-noise ratio of acoustic arrival peaks.
• Showcased the potential for monitoring directional, coherent ambient sound, including fin whale chorus.

Conclusions:

• Long-term ambient noise interferometry is a viable method for deep-ocean acoustic analysis.
• The technique effectively detects complex sound propagation features like multi-path arrivals.
• This approach offers a powerful tool for long-term monitoring of marine soundscapes and vocalizing species.