Continental Shelf-scale Passive Ocean Acoustic Waveguide Remote Sensing of Marine Ecosystems, Dynamics and Directional Soundscapes: Sensing Whales, Fish, Ships and other Sound Producers in near Real-Time

Passive ocean acoustic waveguide remote sensing (POAWRS) employs a large aperture coherent hydrophone array system to provide instantaneous wide-area (~100 km diameter region) remote sensing and monitoring of sound producers in marine ecosystems, including detection, localization and classification. Coherent array processing techniques such as beam-forming can (1) enhance the signal-to-noise ratio (SNR) of received signals by filtering noise outside of the signal beam, (2) provide estimates of signal bearing, and hence (3) enhance signal detection ranges by one to two orders of magnitude over that of a single hydrophone. A bearing-time trajectory sequence of detected signals from a sound producer can be employed for localization estimation, from which geographic maps of different sound producers can be generated. Here we provide examples of POAWRS wide-area sensing of sound producers in several distinct marine ecosystems, the Gulf of Maine (2006), the Great South Channel and deep ocean south of Rhode Island (2021) off the US Northeast coast, and the Norwegian and Barents Seas (2014). The sound producers include marine mammal vocalizations from a large variety of baleen and toothed whale species, fish grunts and other fish-produced signals; ship generated tonal and broadband sounds; seismic airgun and other natural and manmade sound sources. When POAWRS observations are combined with other sensing modalities, such as OAWRS echosounding and imaging, ultrasonic echosounding, tagging, visual and underwater photography, important behavioral dynamics including predator-prey interactions at a variety of temporal-spatial scales can be elucidated. POAWRS applications can include real-time environmental assessment for seismic surveys and other geophysical prospecting activities, monitoring marine ecosystems around wind farms and marine directional soundscaping, in addition to maritime surveillance and defense.