Very low frequency ambient noise measurements in the Ionian Sea: data report

Abstract

This memorandum describes an experiment and provides a data

summary and quality assessment of very low frequency data of ambient noise collected in the Ionian Sea in June 1992. The experiment was a joint operation between SACLANTCEN and the Marine Physical Laboratory (MPL) of Scripps Institution of Oceanography, USA. The sensor system had been supplied by MPL, it consisted of 11 Swallow floats that are neutrally buoyant freely drifting glass spheres which were equipped with sensors to measure acoustic pressure and 3-dimensional particle velocity in the frequency range between 0.5 and 25 Hz. The data of the four sensors can be combined to yield the time averaged acoustic intensity vector, i.e. magnitude and direction of the acoustic propagation obtained in a single point in space. The acoustic data are complemented by a set of environmental data including seismic events, very low frequency propagation and commercial ship surveillance. All the data are of excellent quality, well documented and therefore, can be used to further investigate the very low frequency ambient noise field in the Mediterranean Sea.