Modeling Fluctuations in Depth-Integrated Acoustic Intensity Induced by Internal Waves Along a 2-D Track

Abstract

Accurate spatio-temporal prediction of the acoustic field in the presence of internal waves depends largely on one's ability to accurately prescribe water column properties for the acoustic model. This paper describes a data-based methodology for reconstructing a 2-D water column sound-speed profile (WCSSP) from multiple oceanographic moorings deployed in a line. The methodology gives particular attention to reconstructing the 2-D spatio–temporal evolution of the internal wave field. Acoustic predictions are made from an acoustic propagation model with the reconstructed WCSSP as an input. Measured and modeled depth-integrated acoustic intensities are compared to indirectly evaluate the fidelity of the WCSSP reconstruction. Because of the complicated spatio–temporal evolution of the internal wave field in the experimental region, it was found that reconstructing the WCSSP from multiple moorings is important for accurately predicting temporal fluctuations of the depth-integrated acoustic intensity. The average overlap coefficient of 31 pairs of measured/modeled intensity distributions improved from $0.60\pm 0.23$ to $0.79\pm 0.06$ as the number of moorings used in the WCSSP reconstruction increased from one to four.