Mapping coastal circulations using moving vehicle acoustic tomography.

With the increased availability of highly maneuverable unmanned surface/underwater vehicles, abundant ocean data can now be collected. This study uses tomographic techniques to extend the survey area covered by moving vehicles. An acoustic reciprocal transmission experiment was conducted using three tomographic sensors installed on an autonomous underwater vehicle, a fishing ship, and a buoy. The distributed sensing method is applied for currents estimation. The estimated currents near the ship show consistent results with the direct measurements. In particular, an anticyclonic circulation was revealed. Further, a general least-squares method is employed to improve the estimate of this vortical structure.