Enhanced deep water acoustic range estimation based on ocean General Circulation Models

Improved acoustic range estimation supports ocean climate monitoring, ocean model improvement, and underwater navigation, and is limited by the availability of accurate models of ocean sound speed variability. I will describe efforts to test the limits of currently available GCM data to accurately estimate absolute range based on data collected during the PhilSea10 experiment using 510 km source-receiver separation. The methods compare observed acoustic records with synthetic records computed through the GCM ocean sound speed model. The most reliable ranging methods, emphasizing the most reproducible parts of the data records, are able to achieve 20 m or better accuracy. The principles underlying these methods are transportable and are expected to provide reliable range estimates in a broad range of deep-water settings. Generalization to ocean regions with stronger, less well characterized dynamics, is a major challenge, requiring new sources of data to constrain the models.