Spatial and temporal variations in acoustic propagation in Dabob Bay during PLUSNet'07 Exercise

• Published in: The Journal of the Acoustical Society of America 2008-05, Vol.123 (5_Supplement), p.3894-3894
• Main Authors: Xu, Jinshan, Lermusiaux, Pierre, Haley, Patrick, Leslie, Wayne, Logutov, Oleg
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.2935850

We present spatial and temporal variability of the acoustic field in Dabob Bay during the PLUSNet'07 (Persistent Littoral Undersea Surveillance Network) Exercise. The study uses a 4D (3D in space plus 1D in time) data-assimilative numerical ocean model to provide inputs to an acoustic propagation model. The Havard-Ocean-Prediction-System with in-situ CTD measurement assimilation provided output forecasts with a 300-m and 1-to-5-m resolution in the horizontal and vertical direction, for a 3-h interval within a 15-day period. This environmental data as the input to acoustic modeling allowed prediction and study of the (semi-)diurnal temporal variations of the acoustic field, as well as the varying spatial structures of the field. Using the one-way coupled-normal-mode code, along- and across-sections in the Dabob Bay acoustic field structures at 100, 400, and 900 Hz were forecasts and studied for various source depths. Interesting propagation effects such as the acoustic transmission-loss fluctuations with respect to the source depth and frequency as a result of the regional ocean variability, wind forcing, and tidal effects are discussed. The novelty of this work lies in the accuracy of the acoustic transmission-loss prediction in the littoral region by physically coupling the real-time ocean prediction system to acoustic modeling. This work also offers a potential extension to a 4D acoustic modeling.