Exploring surface source contributions to ocean ambient noise interferometry with airgun shots

Abstract

A seismic reflection survey conducted directly over two bottom-mounted hydrophones in the north-east Pacific Ocean is used to explore how surface source locations affect ambient noise interferometry for the two hydrophones. The airgun shots are used as an approximation of an impulsive sound source at a discrete location, which allows us to investigate spatial contributions to the cross correlation between the two hydrophones. Simulated and experimental results are presented. The contributions to the cross correlations are explained by different reflections off the surface or bottom of the ocean, and a discussion about what can and cannot be inferred about the emergence to the Green's function is presented.

Using Ocean Ambient Sound to Measure Local Integrated Deep Ocean Temperature

“…The ambient soundscape at these hydrophones is dominated by wind, shipping, and fin‐whale vocalizations (Ragland, Schwock, et al., 2022). It has been experimentally demonstrated that the sound sources that contribute to the multi‐path EGF arrivals are local surface sources (Ragland & Abadi, 2022a). Because of this, the dominant illuminating sound source is likely local surface wind noise, which at the spatial scale of the hydrophone array will result in diffuse surface illumination.…”