Arctic Climate change Whales and seals

Wind-driven ambient noise characteristics in the Western Canadian arctic

Shajahan, N., Halliday, W., Barclay, D., Melling, H., Neimi, A. & Insley, S.

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An analysis of ambient noise data collected from seven locations in the western Canadian Arctic during ice-free seasons.

Key points

• This study focused on understanding the effects of wind-generated noise in the western Canadian Arctic, particularly during ice-free periods.
• Wind noise could have an increasing impact on the Arctic’s soundscape as climate change leads to longer ice-free periods, potentially affecting marine mammal communication.
• Examining the relationship between wind speed and noise levels also allows us to create a baseline for ambient noise in the Arctic against which noise pollution can be better understood.

Abstract

Wind-induced ambient noise is generally considered as the resultant noise field due to the superposition of sound sources distributed randomly at the ocean surface. Most of the background noise in the ocean is generated by surface agitation at frequencies between 20 Hz and 50 kHz. Individual and collective bubble oscillations created by breaking waves mainly contributes to sound generation. Noise is produced by collective bubble oscillations at lower frequencies (<500 Hz), while individual bubble oscillations produce noise at higher frequencies (>500 Hz). Early studies of ocean ambient noise showed a direct relationship between wind speed and measured spectrum amplitude. However, the wind speed dependence of ambient noise exhibits clear frequency dependence and significant variation among different studies were observed, perhaps due to measurement location characteristics. Spectral features of wind noise can also be affected by propagation conditions and sensor depth, especially in shallow waters.⁶ In addition to measurements, analytical and numerical models were also developed to study the spectral and spatial features of surface generated ambient noise. In recent years, long-term passive acoustic recordings have been used to develop empirical wind noise models. Due to the omnipresence of wind generated noise, it is essential to understand its spectral and spatial features in applications such as sonar performance modelling, ocean environment inversions, and marine mammal monitoring.

The western Canadian Arctic is experiencing longer ice-free periods due to climate change in coastal and offshore areas. Consequently, during the summer and fall months, wind-generated noise dominates the Arctic ambient sound field and may be increasing as climate change progresses. Thus, understanding the frequency and wind speed dependence of ambient noise during ice-free periods is critical. Studies mainly focusing on wind-generated noise in the western Canadian Arctic are rather limited. With data collected from seven different locations, this work aims to characterize wind-generated ambient noise in this region. A logarithmic model based on frequency and wind speed dependence has been developed using the measured data between 50 Hz and 10 kHz. Due to sporadic ship noise events in the area, the data can also be used to compare against available empirical wind noise models.

The Arctic has undergone rapid changes due to climate change and the loss of sea ice, which impact the habitats of marine mammals. A prolonged ice-free season in the Arctic could increase the contribution of wind-driven noise to the overall sound field. Therefore, characterizing the benchmark of wind generated noise is important for detecting, identifying, and localizing marine mammal vocalizations. Also, increased wind-generated ambient noise may reduce the active listening space of marine mammals and soniferous fishes. Since ambient noise is location-specific, determining the wind noise of a specific region using measurements or models from another region might not be feasible. Technological advances have allowed for longer monitoring periods of passive acoustic data in the Arctic. These large-scale (temporal and geographic) data provide an excellent opportunity to examine wind noise in the Arctic.

Recommended citation

Shajahan, N., Halliday, W., Barclay, D., Melling, H., Neimi, A. & Insley, S. (2025). Wind-driven ambient noise characteristics in the Western Canadian arctic. Acoustical Oceanography. https://doi.org/10.1121/10.0035591