Multi-year soundscape analysis from deep-water moored receivers near the New England Seamounts

A network of four Moored Autonomous Noise Recorders (MANRs) was deployed in the vicinity of the Atlantis II Seamounts for 52 days during the 2023 New England Seamounts Acoustics (NESMA) pilot experiment and for 5 months during the 2024 NESMA field experiment. In each experiment, two MANRs were placed on the steep flanks of the Atlantis II Seamounts and two were placed in the abyssal plain. Receiver depths ranged from 2500 to 4475 m. The moored receivers provided stable observation platforms in a region with highly variable and occasionally strong currents. This network of receivers was designed to investigate the feasibility of utilizing passive acoustic remote sensing methods to study a highly dynamic ocean region with complex bathymetry. Strong ocean variability at the experimental site was induced by its proximity to the Gulf Stream and, in 2024, the passage of Hurricane Ernesto. The analyses presented in this paper are based on ambient sound spectra and spectrograms acquired concurrently by multiple near-bottom receivers. The relation between spectral features of ambient sound and ocean dynamics is explored along with the statistical distribution of ambient sound, spatial and temporal variability of ambient sound spectra, and the dependence of ambient sound on environmental conditions.