Directionality of ambient noise measurements in Barrow Strait of the Canadian Arctic

Abstract

In August 2012, a field trial was carried out in Barrow Strait south of Gascoyne Inlet in the vicinity of 74.630 N 91.340 W. Underwater acoustic data was collected using a JASCO Autonomous Multichannel Acoustic Recorder (AMAR) and in-house designed sensor systems called Starfish Cubes. The Starfish Cubes were deployed twice, at different locations, each for one week duration and at depths of approximately 110 m. The Cubes consist of seven hydrophones with 1 m spacing and geometrically configured as three cross-dipoles with a central hydrophone, and have an operational frequency range of 5—750 Hz. During the trial 400 and 500 Hz tones were transmitted from discrete locations at various ranges. By using a beamforming method the tones were used to determine the orientation of the Starfish Cubes during their data collection periods. This enables investigation of the horizontal and vertical directionality of ambient noise. Unique localized sources contributing to the ambient noise are discussed such as a nearby grounded iceberg and a low frequency wandering tonal.