Mapping coastal circulations using moving vehicle acoustic tomography.

Area of Science:

• Oceanography
• Acoustic Tomography
• Robotics

Background:

• Increased availability of unmanned surface/underwater vehicles enables extensive ocean data collection.
• Traditional oceanographic surveys are limited in scope and spatial coverage.

Purpose of the Study:

• To extend the survey area for oceanographic data collection using mobile platforms.
• To develop and apply distributed sensing methods for accurate current estimation.
• To investigate vortical structures in ocean currents.

Main Methods:

• Acoustic reciprocal transmission experiments using three tomographic sensors.
• Deployment of sensors on an autonomous underwater vehicle, a fishing ship, and a buoy.
• Application of distributed sensing and general least-squares methods for current estimation.

Main Results:

• Successfully extended the survey area using tomographic techniques with moving vehicles.
• Estimated ocean currents near a ship, showing consistency with direct measurements.
• Revealed an anticyclonic circulation, a significant vortical structure.

Conclusions:

• Distributed acoustic sensing offers a viable method for extending oceanographic survey areas.
• The study successfully identified and improved the estimation of an anticyclonic circulation.
• This approach enhances the capability for detailed ocean current mapping and analysis.