Resolving meso-scale seabed variability using reflection measurements from an autonomous underwater vehicle

Area of Science:

• Geophysics
• Acoustics
• Oceanography

Background:

• Seabed geoacoustic variability influences acoustic propagation.
• Understanding of fine (<10^0 m) and large (>10^3 m) scales exists.
• Meso-scale (10^0–10^3 m) variability remains poorly understood.

Purpose of the Study:

• To resolve and characterize geoacoustic meso-scale variability.
• To investigate the impact of meso-scale variability on acoustic modeling.

Main Methods:

• Measurements of meso-scale geoacoustic properties on the outer shelf.
• Analysis of horizontal layer thickness variations.
• Observation of rapid changes in layer properties and reflection coefficients.

Main Results:

• Three classes of meso-scale variability were identified.
• Layer thickness variability correlated with seismic data.
• Rapid changes in layer properties and reflection coefficients indicate strong horizontal variability.
• Variability at meter scales or less was observed.

Conclusions:

• Meso-scale geoacoustic variability is significant and complex.
• Previously neglected variability classes impact acoustic modeling.
• Insights into effects on long-range acoustic propagation and reverberation were gained.