Synthetic array processing of ocean ambient noise for higher resolution seabed bottom loss estimation

Area of Science:

• Ocean acoustics
• Acoustic signal processing
• Geophysical exploration

Background:

• Accurate prediction of underwater acoustic transmission loss is vital for various oceanographic applications.
• Ocean bottom loss is a critical parameter influencing transmission loss predictions.
• Current methods using ambient ocean noise and vertical arrays have resolution limitations due to finite array lengths.

Purpose of the Study:

• To improve the resolution of ocean bottom loss estimation.
• To overcome the smoothing effects caused by finite array beam widths in existing methods.
• To demonstrate a novel technique for enhancing bottom loss estimation accuracy.

Main Methods:

• Utilizing the noise coherence function derived from ambient ocean noise.
• Synthetically expanding the noise coherence function, analogous to increasing array length.
• Employing a full wave ocean noise model for simulated demonstrations.

Main Results:

• The synthetic expansion of the noise coherence function significantly improves the resolution of bottom loss estimates.
• Simulations confirm the effectiveness of the proposed method in overcoming finite array limitations.
• Enhanced resolution allows for more detailed characterization of the ocean sub-bottom.

Conclusions:

• The synthetic expansion of the noise coherence function offers a powerful approach to enhance ocean bottom loss estimation.
• This method provides a valuable tool for improving acoustic propagation models and understanding ocean acoustic environments.
• The technique is particularly beneficial in scenarios where long acoustic arrays are impractical.