Subsurface acoustic ducts in the Northern California current system.

This study investigates the subsurface sound channel or acoustic duct that appears seasonally along the U.S. Pacific Northwest coast below the surface mixed layer.

Open ocean ambient noise data in the frequency band of 100 Hz-50 kHz from the Pacific Ocean.

Bubbles from wind generated breaking surface waves are the dominant ambient noise source [Dean and Stokes, Nature 418, 839-844 (2002)]. With ambient noise data collected in the open ocean between 100 Hz and 50 kHz from 1999 to 2022, the ambient noise level is observed to sharply decrease as wind speed increases beyond 15 m/s for frequencies higher than 4 kHz. Data-model comparisons show a mismatch, as existing models including the Wenz curves [Wenz, J.

Macroscopic observations of diel fish movements around a shallow water artificial reef using a mid-frequency horizontal-looking sonar.

The twilight feeding migration of fish around a shallow water artificial reef (a shipwreck) was observed by a horizontal-looking, mid-frequency sonar. The sonar operated at frequencies between 1.8 and 3.

Acoustic scattering from a solid aluminum cylinder in contact with a sand sediment: measurements, modeling, and interpretation.

Understanding acoustic scattering from objects placed on the interface between two media requires incorporation of scattering off the interface. Here, this class of problems is studied in the particular context of a 61 cm long, 30.5 cm diameter solid aluminum cylinder placed on a flattened sand interface.