Source Operations Summary

Scripps Institution of Oceanography, University of California, San Diego received approval to retain in place and reuse the power cable and sound source previously installed and used by the Acoustic Thermometry of Ocean Climate (ATOC) Project for an additional five years. The source is located on the seafloor at a depth of 807 meters (2648 ft.), approximately 8 nautical miles (14.8 km) north of Kauai at 22°20.94'N, 159° 34.18'W.

As part of the NPAL project, transmissions are continuing in order to 1) perform the second phase of research on the feasibility and value of large-scale acoustic thermometry; 2) study the behavior of sound transmissions in the ocean over long distances; and 3) conduct studies on the possible long-term effects from the sound transmissions on marine life.

The typical transmission schedule consists of six 20-minute transmissions (one every four hours), every fourth day, with each transmission preceded by a 5-minute ramp-up period during which the signal intensity is gradually increased. The signals transmitted by the source have a center frequency of 75 Hertz (Hz) and a bandwidth of approximately 35 Hz. Approximately 260 Watts of acoustic power are radiated during transmissions. At 1 meter from the source, the sound intensity is about 195 decibels (dB) referenced to the intensity of a signal with a sound pressure level of 1 microPascal (µPa)(on a “water standard” basis).

NPAL source transmissions began on 25 January 2002 and will continue through 2006.

The NPAL project is funded by the Office of Naval Research (ONR) and is being carried out by Scripps in conjunction with the Applied Physics Laboratory of the University of Washington.

Kauai Source Permitting

NPAL Source Operations Summary