[S-CG45] Ocean Floor Geoscience

[SCG45-18] Initial results of sea trials on bathymetric survey performance of “AUV-NEXT”: aiming to acquire higher-quality bathymetric data

*MASANAO SUMIYOSHI¹, Ryosuke Nagasawa¹, Takashi Hashimoto¹, Kenji Nagahashi², Takao Sawa², Tadahiro Hyakudome², Takeshi Nakatani², Tatsuya Aso², Yusuke Yokota³ (1.Hydrographic and Oceanographic Department, Japan Coast Guard, 2.JAMSTEC, 3.Institute of Industrial Science, University of Tokyo)

Keywords:Autonomous Underwater Vehicle (AUV), “AUV-NEXT”, Bathymetric survey, Bathymetric side scan sonar (Bathy-SSS), Multibeam echosounder (MBES), Sea trials on bathymetric survey performance

In AUV bathymetric survey, since AUV can approach the seafloor for ocean mapping, it is possible to acquire bathymetric data with higher resolution and less noise even at the deep waters. However, in order to acquire higher-quality bathymetric data in an actual AUV bathymetric survey, it is required to establish a method for acquiring bathymetric data with sufficiently high reproducibility within the range of the bathymetric data precision. To aim at such a standardization of AUV bathymetric survey technology for acquiring high-quality bathymetric data, the JAMSTEC and JHOD conducted sea trials to verify an actual bathymetric data performance using the "AUV-NEXT".
In these sea trials, in March and November 2020, the "AUV-NEXT" dived around the Nankai Trough area (at depths of 2500-2800 m) offshore the Kii Peninsula and the Suruga Bay, and bathymetry was surveyed by using a bathymetric side scan sonar (Bathy-SSS: EdgeTech 2205AUV) installed on the AUV. After sufficient preliminary tests such as DVL calibration, which is important for AUV navigation, and patch test for correcting the mounting angle of the sonar, bathymetric data were acquired, and by confirming the reproducibility of bathymetric data to which various necessary corrections were applied, we were able to find out some important points in AUV bathymetric survey technology. As a result, higher quality bathymetric data can be acquired by using the “AUV-NEXT”. In this paper, we report the initial results of these sea trials.