A normal mode projection technique for array response synthesis in range-dependent environments.

Area of Science:

• Ocean acoustics
• Array signal processing
• Computational physics

Background:

• Simulating acoustic array responses in range-dependent environments is computationally challenging.
• Accurate modeling is crucial for underwater acoustic applications like sonar and communication.

Purpose of the Study:

• To develop and validate a computationally efficient method for simulating beam time series response of arbitrary acoustic arrays.
• To combine parabolic equation (PE) forward modeling with local normal mode analysis for improved accuracy in range-dependent environments.

Main Methods:

• Computing acoustic pressure fields using PE at the array's center.
• Decomposing the field into local complex normal mode amplitudes.
• Applying range-independent normal mode theory and plane-wave beamforming, utilizing a matrix computation for depth-to-angle mapping.

Main Results:

• Demonstrated accuracy with two broadband range-independent examples.
• Successfully reproduced qualitative features in shallow-water (Florida coast) and deep-water (seamount scattering) range-dependent experiments.
• Validated the efficiency and accuracy of the combined PE and normal mode approach.

Conclusions:

• The proposed method provides a robust and accurate approach for simulating acoustic array beamforming in complex underwater scenarios.
• This technique enhances the understanding and prediction of acoustic signal propagation and array performance in realistic oceanic conditions.