2025 Volume 81 Issue 17 Article ID: 25-17102
In August 2020, bottom-layer hypoxia in Mikawa Bay rapidly dissipated over a short period. Hydrodynamic model simulations suggest that the intrusion of bottom water from open ocean, driven by density currents, plays a significant role. However, challenges remained in accurately reproducing the associated dissipation in bottom-layer dissolved oxygen resulting from the bottom-water intrusion. This study aimed to improve the reproducibility of bottom-water intrusion event in August 2020 using salinity as an indicator of such intrusion. A regional coastal data assimilation was applied, integrating the water temperature and salinity observations from 6 locations in Ise and Mikawa days. As a result, the RMSE of the bottomlayer salinity at the Mikawa Bay No. 1 buoy decreased from 1.77 to 0.94 when data assimilation was applied. This improvement is attributed to the effective incorporation of in-bay observational datas and high-frequency data assimilation, which allowed for assimilation corrections across the entire Mikawa Bay.
