Acoustical remote sensing of ocean internal waves: progress and remaining challenges

The state of the art for using acoustics to characterize ocean internal waves is reviewed. Results are presented for several experiments that span a wide range of oceanographic conditions. The inclusion of the proper physics in the model for acoustic propagation is shown to be crucial. Examples of remaining challenges include developing techniques to handle steeply turning ray paths, and generalizing Rytov theory to calculate two-point statistics in the presence of a sound speed gradient