Under-ice ambient noise and its masking effect on marine mammals in the Arctic

Climate change is changing the pattern of sea ice in the Arctic, which increases underwater ambient sound levels during the ice-covered season. The Arctic is home to multiple marine mammal species, even during the winter, which rely on the underwater acoustic environment for acoustic communication. Thus, climate change may be impacting the ability of these animals to communicate. Under-ice ambient noise is primarily generated by wind acting on the ice surface, rapid temperature changes, and impulsive transient signals resulting from ice cracking and ridging. To characterize under-ice ambient noise, acoustic data were collected from several locations in the western Canadian Arctic in this study. To determine the relationship between the received noise level, and wind speed and ice concentration, correlation analysis was used. For the detection and analysis of broadband transient events in the acoustic data, a spectrogram image processing approach was used. The spectral characteristics of transient events were generated using measurements and a random pulse train model. Furthermore, the wind and ice generated noise components were combined to predict the total ambient noise field in an ice-covered ocean using a wavenumber integral model. Finally, the model together with measurements was used to assess how ice-generated noise can cause communication masking in marine mammals such as ringed seals and bearded seals.