65 / 2023-07-25 14:33:35

Response of the West Pacific Ocean Current to Changes in Bathymetry and Coastline - A Study Based on the Regional Ocean Model (ROMS)

West Pacific; Ocean currents; ROMS; Sea level change; bathymetry change

During the geological evolution of the Earth, plate tectonics and sea level changes have caused changes in bathymetry and coastlines, thereby affecting the changes in global ocean circulation patterns. Studying the response of ocean currents to changes in coastlines and bathymetry can help to understand the changes and driving factors of ocean circulation patterns during geological evolution. In this study, six sets of regional ocean model sensitivity experiments were carried out to explore the response of western Pacific Ocean currents to changes in bathymetry and coastlines caused by sea level changes. The experiment was carried out under ideal and realistic bathymetric conditions of modern sea level, the maximum sea level of the last glacier (sea level drop ~ 120 m) and the melting of the global ice sheet under extreme melting conditions (sea level rise ~ 65 m) with the regional ocean model (ROMS). The results show that compared with the actual bathymetry, the annual average flow velocity increases and the western boundary Kuroshio is stood out from under ideal bathymetry. Compared with modern sea level, the Taiwan Strait is closed in the case of low sea level, and the Kuroshio invasion is cut off, resulting in an increase in the Kuroshio flow velocity in the East China Sea. Meanwhile, Java Sea emerges as land, causing the disappearance of seawater replenishment from the South China Sea, and the almost closed Makassar Strait and the disappearing of Timor Sea lead to the weakening of Indonesian throughflow. Compared with modern sea level, the area of the Bohai Sea increases in the case of high level; however, the widening of the Taiwan Strait is limited, resulting in no significant change in flow velocity; the channels between Sumatra Island and adjacent islands are widened and deepened, splitting the Indonesian throughflow and resulting in a significant decrease in the flow velocity of Timor Sea. These results show that the coastline changes could cause significant response of the western Pacific Ocean currents, especially Kuroshio and Indonesian throughflow, supporting the theory that coastline and bathymetry changes are important factors constraining changes in ocean circulation patterns during geological evolution.