Interannual variability in surface circulation of the East/Japan Sea: Threedimensional numerical model simulations

Abstract

In addition to predominant seasonal variability, the East/Japan Sea shows relatively large interannual variability in the surface circulation. However, possible mechanisms for the interannual variability have been poorly understood. In this study, we aimed to identity factors contributing to interannual variability using a three-dimensional high-resolution (3 km in horizontal) numerical model with the most plausible three factors: Korea Strait transport, atmospheric forcing and internal variation in East/Japan Sea. When internal variability was only considered, the Yamato and Ulleung Basins revealed considerable interannual variability. But, interannual variability was overestimated in the northern basin. Thisoverestimation in the northern basin was slightly reduced when interannual variability in the Korea Strait transport was added. The internal variation in the Korea Strait transport further contributes to strengthening of interannual variability in the southern basin. Although the mechanisms controlling the interannual variability in the surface circulation seem to depend on region by region, our findings suggest that the internal variability is the greatest contribution to internal variability in the surface circulation in the East/Japan Seas. study, we aimed to identity factors contributing to interannual variability using a three-dimensional high-resolution (3 km in horizontal) numerical model with the most plausible three factors: Korea Strait transport, atmospheric forcing and internal variation in East/Japan Sea. When internal variability was only considered, the Yamato and Ulleung Basins revealed considerable interannual variability. But, interannual variability was overestimated in the northern basin. Thisoverestimation in the northern basin was slightly reduced when interannual variability in the Korea Strait transport was added. The internal variation in the Korea Strait transport further contributes to strengthening of interannual variability in the southern basin. Although the mechanisms controlling the interannual variability in the surface circulation seem to depend on region by region, our findings suggest that the internal variability is the greatest contribution to internal variability in the surface circulation in the East/Japan Seas.