Environmental drivers of the low-frequency ambient noise on the Chukchi Shelf

This study presents an analysis of the low frequency (250–350 Hz) ambient noise (after individual transient signals are removed) recorded on the Chukchi shelf during the CANAPE experiment from October 2016 to July 2017. Ambient noise drivers are evaluated by correlating noise levels with external oceanographic data including local wind speed, local ice coverage, and distant ice drift magnitude. Also, the experimental area is known to be home of the Beaufort duct, a warm layer intrusion which creates an acoustic channel that favors long range propagation and impacts the ambient noise. The study shows that, as usual in polar areas, the ambient noise is quieter and wind force influence is reduced when the sea is ice-covered. More interestingly, the study demonstrates that the ambient noise drastically reduce (up to 10 dB/Hz) when the Beaufort duct disappears. It also shows that a large part of the noise variability is driven by distant cryogenic events. [Work supported by the Independent Research & Development Program at WHOI and by the Office of Naval Research.]