[A-OS17] Physical Oceanography (General)

[AOS17-P02] Downscaled Flow Modeling Reveals the Current Characteristics of Deep-sea Seamounts

*Naoki Saito¹, Masayuki Nagao¹, Kazutoshi Horiuchi², Junpei Minatoya³, Atsushi Suzuki¹ (1.National Institute of Advanced Industrial Science and Technology, 2.Forecast Ocean Plus, Inc., 3.Japan Oil, Gas and Metals National Corporation)

Keywords:Seamount, Flow model, Downscaling, Taylor cap, Tidal current

The topography of seamounts often produces complex flow fields. It is important to clarify the characteristics of this flow to understand the seamount environment. In this study, flow modeling was conducted for a deep-sea seamount in the Northwestern Pacific Ocean to characterize the flow regime in the area. The computational method was downscaling using POMgcm type ocean general circulation model with the ocean reanalysis data JCOPE2M and the tidal model OTIS as boundary conditions. The calculated flow fields were compared against observed data, and our calculations accurately reproduced observations of the M2 tide, K1 tide, and mean currents. A “Taylor cap,” which is a clockwise-circulating flow field, was identified on the seamount flat top. Flow speeds on the flat top were the highest at the northern and southern ends of the seamount, averaging about 5 cm/s, and were relatively small at the center of the flat top, ranging from 0 to 2 cm/s. Tidal currents were also amplified at the flat top; the amplitude of the M2 tide was 0.91 cm/s at the base but 4.57 cm/s at the summit, about a five-fold difference.