Analysis of frequency-dependent acoustic enhancement from a seamount

During the 2023 New England Seamounts Acoustics (NESMA) pilot experiment, continuous measurements were made of underwater acoustic propagation and scattering near a seamount from close range through the first deep-water acoustic convergence zone. Measurements were made by positioning a stationary mid-frequency source at a shallow depth over the plateau of the Atlantis II seamount and then towing Penn State’s Three Octave Research Array (THORA) to a range of 85 km from the source. Low- to mid-frequency acoustic data were beamformed to improve signal-to-noise ratio and reduce own-ship noise, and transmission loss was estimated using narrowband processing techniques. Comparison of the data with ray and parabolic equation-based models helped to develop an understanding of the influence of the seamount bathymetry, roughness, and sound speed profile. This talk will discuss details of these unique measurements, modeling, and data analysis confirming a frequency-dependent change in acoustic enhancement within the first deep-water shadow zone.