Acoustic field and array response uncertainties in stratified ocean media

Area of Science:

• Ocean acoustics
• Probability theory
• Waveguide modeling

Background:

• Ocean environments present complex acoustic propagation challenges due to uncertainties in parameters like sound speed and attenuation.
• Accurate computation of acoustic field and array beam power probability density functions (pdfs) is crucial for underwater acoustic system performance assessment.
• Stratified, attenuating ocean waveguide models are commonly used to represent these environments.

Purpose of the Study:

• To apply the change-of-variables theorem to compute acoustic field and array beam power pdfs in uncertain ocean waveguides.
• To investigate the functional properties of these pdfs in one and two-layer waveguide models.
• To analyze the impact of acoustic parameter uncertainties on the computed pdfs.

Main Methods:

• Utilized the change-of-variables theorem from probability theory.
• Employed the normal-mode representation for acoustic propagation.
• Computed acoustic field and array beam power pdfs directly from parametric probability density functions (pdfs).
• Investigated one and two-layer stratified, attenuating ocean waveguide models.

Main Results:

• Computed acoustic field and array beam power pdfs using parametric pdfs and the change-of-variables theorem.
• Observed irregular functional behavior and singularities in the field and beam power pdfs for two-dimensional uncertainties (sound speed and attenuation).
• These irregularities are linked to stationary points in the acoustic propagation mapping from parameter to field/beam power space.

Conclusions:

• The change-of-variables theorem provides a direct method for computing acoustic pdfs in uncertain ocean environments.
• Acoustic parameter uncertainties can lead to complex and singular behavior in acoustic field and beam power distributions.
• Findings have implications for evaluating methods like orthogonal polynomial expansion for acoustic pdf computation.