2aAO4. Acoustically focused oceanographic sampling in the Haro Strait experiment.

Session: Tuesday Morning, December 3

Time: 8:50

Author: James G. Bellingham
Location: MIT, Cambridge, MA 02139
Author: Henrik Schmidt
Location: MIT, Cambridge, MA 02139
Author: Max Deffenbaugh
Location: MIT, Cambridge, MA 02139
Author: Mark Johnson
Location: Woods Hole Oceanograph. Inst., Woods Hole, MA 02543


The tidal fronts of Haro Strait, British Columbia, are associated with currents in excess of 3 kn, with significant horizontal stratification, leading to significant frontal turbulence and upwelling. Volumetric mapping of these fronts using traditional oceanographic sampling techniques is virtually impossible due to the spatial and temporal aliasing produced by the extremely dynamic oceanography. The concept of acoustically focused oceanographic sampling (AFOS) was developed to overcome this problem. AFOS combines the autonomous oceanographic sampling network (AOSN) [Curtin et al., Oceanography 6(3) (1993)] with acoustic tomography. The network nodes used for communication with and navigation of AUVs is equipped with vertical arrays and tomography sources. In addition an AUV carries a source for adaptive, moving source tomography. The array data are transmitted to shore via a wireless local-area network and processed in real time for estimation of current distribution and frontal geometry. The results are used for adaptively focusing the AUV's sampling of the front using surface mapping side-scan sonars and acoustic Doppler current profilers, as well as CTDs. [Work supported by ONR.]

ASA 132nd meeting - Hawaii, December 1996