AMBIENT NOISE MEASUREMENTS IN THE 200-300-HZ BAND FROM THE GREENLAND SEA TOMOGRAPHY EXPERIMENT

Ambient noise in the 200-300-Hz band was measured every four hours from Sept 1988 to Sept 1989 as part of the Greenland Sea tomography experiment (GSP88). Four transceivers, located in the central Greenland Sea gyre, sampled the noise during a wide variety of ice, wind, and wave conditions, revealing large seasonal variations in the noise field. The environmental conditions were obtained mainly from large-scale remote sensing and numerical modeling, i.e., operational meteorological forecast models, surface wave models, and microwave and infrared satellite imaging (for ice). To understand the noise field, a number of analyses were performed on the noise, wind, ice concentration, and wave-time series, including regressions, auto- and cross correlations, spectra, and acoustic propagation modeling. As a result, a number of environmental noise effects, particularly as related to ice edge noise, are observed. The results generally agree well with previous, shorter time period process oriented studies which used remote sensing as well as in situ ice, wind, and wave measurements. It is seen that prediction of the marginal ice zone (MIZ) noise field for a deep ocean region at the acoustic frequencies examined is feasible using large-scale environmental information.