Joint WA Acoustics Primary '25

This ONR-TFO project continues work to improve the understanding and prediction of mid-frequency sound propagation in coastal environments. This will be accomplished via a collaborative effort between UW-APL Ocean Acoustics ( DJ Tang, T. Hefner ), UW-APL Ocean Physics ( R. Harcourt, J. Mickett ), Scripps Institution of Oceanography ( Y-T Lin, W.S. Hodgkiss ), and NRL Stennis (G. Jacobs, J. Osborne). The primary goals of the fieldwork component of this project are to: Quantify the dependence of the large high-frequency variability (scintillation, when under sampled) in transmission loss due to stratification and internal wave spectra along the acoustic path. Collect highly-resolved towed profiler measurements to allow a statistical representation of high-frequency internal waves to facilitate prediction of TL variability at O (10) minute timescales, and to enable a priori assessment of acoustic signal uncertainty. Collect coordiated oceanographic and acoustic measurements to better quantify the impact of nonlinear internal waves---energetic, ubiquitous and regular on the Washington shelf---on mid-frequency acoustic propagation. Both along and across-wavecrest studies will be carried out. Collect microstructure measurements along with towed profiler measurements to improve our understanding of how acoustic ducts are modified by turbulent mixing. Are ocean model lateral and vertical diffusivity levels realistic? Support APL and Scripps Acoustics field experiments by providing comprehensive moored and towed profiler measurements to resolve the dominant variability of the sound speed environment, allow interpretation of changes to this field, and enable post-experiment acoustic modeling.