Modeling the long-term variability of shelf water intrusion into the Seto Inland Sea, Japan

Long-term observations conducted around Japan have revealed that the pathway of the Kuroshio shows inter-decadal variability, and that it controls the intensity of upwelling of the cold deep shelf water at the shelf-break point. In this study we present results from a numerical model that was developed to reproduce the long-term variability of the intrusion of the deep shelf water into the inner shelf region and thus to investigate the effect of the variability of the pathway of the Kuroshio on the ecosystem in the Seto Inland Sea. Results from a numerical simulation covering a 30-year period show sufficient reproducibility in both the seasonal behavior and the inter-decadal variability of density structure within the inner shelf sea. A significant relationship between the long-term trend in the calculated volume flux into the inner sea and that in dynamic height at the shelf-break point was found in the stratified season, indicating that upwelling of cold deep shelf water enhances cross-shelf circulation and has a major influence on inner shelf-sea hydrographic properties.