The ANKOU is a newly developed, full ocean depth, long-range vector side scan sonar system. The system provides real time vector side scan sonar data to produce backscattering images and bathymetric maps for seafloor swaths up to 10 km on either side of ship's centerline. Complete geometric corrections are made using towfish attitude and cross-track distortions known as foreshortening and layover caused by violation of the flat bottom assumption. Foreshortening and layover refers to pixels which have been placed at an incorrect cross-track distance. Our correction of this topographic distortion is accomplished by interpolating a bathymetric profile and ANKOU phase data. We applied these processing techniques to ANKOU backscattering data obtained from off Boso Peninsula, and confirmed their efficiency and utility for making geometric corrections of side scan sonar data.
The results of IAPSO Standard Seawater (SSW) comparisons are presented for batches P 132 to P 140. We try to match up our data with the previous result of comparison experiment to make the newest "offset table". According to the newest "offset table" proposed in this study, the standard deviation of the batch to batch differences among batches P 132 to P 140 is calculated to be 0.3 × 10-3 in salinity. This value is smaller than the value reported in the previous studies. The quality of SSW, from the point of view of batch to batch differences, has improved recently. The SSW batch P 138 and P 140 were stored in bottles made from borosilicate glass and closed with chemically resistant plastic stoppers, while batches P 133 to P 137 and P 139 were stored in glass ampoules. We measured 30 bottles of P 138 and P 140 along with several ampoules of other batches in order to check the quality, those are, within-batch difference and batch-to-batch difference. The standard deviations (1σ) of 30 repeat measurements on P 138 and P 140 were both 0.3 × 10-3 in salinity. The difference between label-delived and measured salinity of P 138 referred to batch P 137 was -0.1 × 10-3 and that of P 140 reffered to batch P 139 was -0.5 × 10-3 in salinity. These values are comparable with other batches stored in a traditional glass ampoules. This result shows that SSW in a shot-bottle is, at least as for P 138 and P 140 at this moment, almost equivalent to SSW in a glass ampoule in quality.