A noise robust sparse time-frequency representation method for measuring underwater gas leakage rate

Area of Science:

• Marine geology
• Acoustics
• Environmental monitoring

Background:

• Passive acoustic monitors (PAMs) are used to measure seafloor gas leakage rates by analyzing sounds from gas bubbles.
• Accurate estimation of bubble size, derived from frequency peaks, is crucial for quantifying leakage.
• Ocean ambient noise interferes with frequency peak estimation, limiting PAMs' effectiveness in shallow seas.

Purpose of the Study:

• To develop a robust method for accurately measuring seafloor gas leakage rates using passive acoustic monitors.
• To overcome challenges posed by ocean ambient noise in estimating bubble frequencies.
• To improve the reliability of gas leakage measurements in shallow marine environments.

Main Methods:

• Proposed a noise-robust sparse time-frequency representation algorithm.
• Implemented an adaptive thresholding approach for detecting bubble frequencies.
• Validated the method using experimental data with augmented ocean and ship-transit noise.

Main Results:

• The novel method demonstrated improved accuracy in estimating bubble frequencies.
• Successfully addressed the interference of ambient and ship-transit noise.
• Showcased the effectiveness of the noise-robust algorithm and adaptive thresholding.

Conclusions:

• The developed robust measurement method enhances the capability of passive acoustic monitors for gas leakage assessment.
• This approach offers a more reliable way to monitor gas seepage in noisy shallow sea conditions.
• Improved acoustic analysis techniques are vital for accurate environmental monitoring of seafloor gas emissions.