Depth and Seasonal Dependence of Ambient Sea Noise Near the Marginal Ice Zone of the Greenland Sea

Omnidirectional data from seasonal and short-term several days, depth-dependent ambient sea-noise measurements in the 20-to-600-Hz band near the marginal ice zone were recorded in the deepwater basin of the Greenland Sea. Two bottom-anchored, self-supporting buoys, one of which recorded acoustic data for 9 months, were used. The first experiment, conducted between Aug 1972 and July 1973, recorded 1-min samples of sea noise every 4 h from an omnidirectional hydrophone 306 m below the surface. During this time, the ice edge moved over the recording site, providing evidence that the iceline acts as a noise source, raising levels above both open-ocean and icefield values. Seasonal conditions favor the lowest ambient noise levels during midwinter Jan and early summer June, while the highest levels occur during early spring March and early fall Nov. Evidence indicates that the maximum ambient noise levels near the marginal ice zone are 12 to 16 dB higher than the maximum Arctic Ocean values under contiguous ice cover. The second experiment, conducted over a 5-day period, recorded ambient noise at depths of 241, 1,232, 1,537, and 2,375 m. Results indicate that ambient noise levels near the ice edge within the water column depend on speed and direction of wind.