Josette Paquin Fabre, James H. Wilson, Marshall D. Earle
Naval Research Laboratory, Washington, D.C.
The objective was to obtain ambient noise data at offshore positions from outside of the surf zone (2 km from shore) to 7 km offshore for investigations of nearshore acoustic noise generated by waves and surf. The goal after data collection is development of predictive models for nearshore acoustic noise for application to Navy littoral operations.
Four Navy AN/SSQ-53D DIFAR sonobuoys were deployed approximately 2 km, 3 km, 5 km and 7 km from shore during 5 separate high wave height events during October. Deployments were made by leased commercial helicopter in positions away from immediate proximity to other sensors to avoid physical interference. Buoys were moored using a Norwegian type float and a Danforth anchor with extra weight. Transmitted ambient noise data for 0 to 7500 Hz was recorded using a Navy standard sonobuoy reciever inter- faced using an analog to digital (A to D) converter connected to a SUN Workstation. Data was recorded onto 8 mm data tapes. Several hours of analog data were also recorded. Data will be analyzed in conjunction with wave and surf measurements in addition to any environmental information from other experiments to develop and improve theoretical nearshore acoustic noise models.