OCEAN ACOUSTIC WAVEGUIDE REMOTE SENSING(OAWRS)

Helen Dickson

REVIEW: ACTIVE ACOUSTIC SENSING

An acoustic signal is generated Sound waves travel through the water and

scatter off objects Backscattered sound is recorded

REVIEW: CONVENTIONAL FISH FINDING SONAR (CFFS)

Uses active acoustic sensing Sends sound waves straight down through

the water column

PROBLEMS OF CONVENTIONAL FISH FINDING SONAR

Attenuation Frequency Image size Sampling frequency

OCEAN ACOUSTIC WAVEGUIDE REMOTE SENSING

Method of active acoustic sensing Developed by MIT Sends sound waves horizontally through

the water column

ACOUSTIC WAVEGUIDES

Physical structures for guiding waves Allow acoustic waves to travel long distances

with little attenuation The continental shelf as a waveguide

OCEAN ACOUSTIC WAVEGUIDE REMOTE SENSING

Little attenuation Lower frequency Much larger image (1,000s of square km’s) Images created every minute (or less)

IMAGE GENERATED BY OAWRS

MOVIE GENERATED BY OAWRS

APPLICATIONS

Shoal Characteristics: Formation (critical density) Migration Leaders

Monitor and conserve fish populations Identify fish species based on return signal

APPLICATIONS

Acoustic clutter Acoustic returns from objects in the water other

than the intended target Is it a submarine or is it a school of fish?

Important in Navy operations OAWRS allows more detailed information to be

gathered

REFERENCES Holden, Constance. Sound Sightings. 2006. Science. 313(5788):777

 Makris, Nicholas C., et al. Fish Population and Behavior Revealed by Instantaneous

Continental Shelf-Scale Imaging. 2006. Science. 311(5761):660-663.

 Makris, Nicholas C. et al. Critical Population Density Triggers Rapid Formation of

Vast Oceanic Fish Shoals. 2009. Science. 323(5922):1734-1737.

 Makris, Nicholas C. Acoustic Clutter and Ocean Acoustic Waveguide Remote Sensing

(OAWRS) in Continental Shelf Environments.

http://www.onr.navy.mil/sci_tech/32/reports/docs/08/oamakris.pdf

 Makris, Nicholas C. Continuous Monitoring of Fish Population and Behavior by

Instantaneous Continental-Shelf-Scale Imaging with Ocean Waveguide Acoustics.

http://www.onr.navy.mil/sci_tech/32/reports/docs/08/npmakris.pdf

 Ratilal, Purnima et al. Long range acoustic imaging of the continental shelf

environment: The Acoustic Clutter Reconnaissance Experiment 2001. 2005. Journal of

The Acoustic Society of America. 117(4):1977-1998.

 Woods Hole Oceanographic Institution. 2007.

http://www.whoi.edu/page.do?pid=10897&i=2041&x=131