Clustering analysis of a yearlong record of ambient sound on the Chukchi Shelf in the 40 Hz to 4 kHz frequency range.

Changes in the Arctic environment with regard to declining sea ice are expected to alter the ambient sound field, affecting both the sound generating processes and the sound propagation. This paper presents acoustic recordings collected on the 150-m isobath on the Chukchi Shelf over a yearlong period spanning October 2016 to October 2017. The analysis uses sections of recordings approximately 12 min long collected six times daily. The measurements were collected on a vertical line array spanning the lower 110 m of the water column. The 25th percentile level is used to characterize the spectral shape of the background sound between 40 Hz and 4 kHz. The ambient sound data are analyzed using k-means clustering to quantify the occurrence of six spectral shapes over the yearlong experiment. Each cluster type is associated with a different sound generation process based on the correlations with environmental observations. The cluster observed most frequently was associated with wind-generated sound based on a correlation of sound level with wind speed as well as occurrence during the open water season. The cluster with the smallest number of observations was attributed to wind effects on frazil ice forming in open leads during the ice-covered season.