Underwater noise emissions from a drillship in the Arctic

Wideband sound recordings were made of underwater noise emitted by an active drillship, Stena Forth, working in 484 m of water in Baffin Bay, western Greenland. The recordings were obtained at thirty and one-hundred meters depth. Noise was recorded during both drilling and maintenance work at ranges from 500 m to 38 km. The emitted noise levels were highest during maintenance work with estimated source levels up to 190 dB re 1 μPa (rms), while the source level during drilling was 184 dB re 1 μPa (rms). There were spectral peaks discernible from the background noise to ranges of at least 38 km from the drillship with the main energy below 3 kHz. M-weighted sound pressure levels were virtually identical to broadband levels for low-frequency cetaceans and about 5 dB lower for high-frequency cetaceans. Signals from the dynamic positioning system were clearly detectable at ranges up to two km from the drillship.