Confirming the Validity of ADCP Velocity Measurements for Physical Environmental Assessment in Japan's Exploration Areas for Cobalt-rich Ferromanganese Crusts

摘要

Current velocity in deep-sea areas must be measured during physicalenvironmental assessments of exploration areas for cobalt-richferromanganese crusts. However, the use of an acoustic Dopplercurrent profiler (ADCP) for velocity measurement in the abyssal zonehas technical disadvantages: (1) Insufficient acoustic backscatter due tothe low density of suspended matter; and (2) difficulty in detecting lowabyssal velocity. Therefore, an appropriate method for confirming thevalidity of velocity measurement results is needed. We examinedphysical aspects of the reliability of ADCP velocity measurementsmade during 1 year, by verifying the Coriolis effect, validating thevelocity power spectrum, and comparing the ADCP results with secondversion of Japan Coastal Ocean Predictability Experiment (JCOPE2)reanalysis velocity data.