[A-CG33] Extratropical oceans and atmosphere

[ACG33-09] Cyclonic-eddy-induced interannual variability of the Kuroshio in the East China Sea

*YUXIANG QIAO¹, Hirohiko Nakamura¹, Shinichiro Kako¹, Ayako Nishina¹, Tomohiko Tomita² (1.Kagoshima University, 2. Kumamoto University)

Keywords:Kuroshio interannual variability, Mesoscale eddy, Water temperature and salinity, East China Sea

In the present study, we focused on the Kuroshio interannual variability in the East China Sea (ECS) along with its effects on the water of the marginal sea. Using satellite altimetry products during 1993–2018, we investigated temporal-spatial features for the Kuroshio in the ECS in terms of current strength and position, mainly based on Hovmöller diagrams along a stream coordinate. Leading modes (strength: 59.8%; position: 40.2%) of empirical orthogonal function analysis to the Hovmöller diagrams show that the strength or position variability of the Kuroshio was spatially coherent throughout the ECS. Furthermore, principal components of the leading modes indicate that the strength and position of the Kuroshio are synchronized in the ECS on a decadal timescale during 1995–2005 but on an interannual timescale during 2005–2016. Using mesoscale eddy trajectories atlas product, we found that the cyclonic eddies with a lifetime exceeding 150 days caused the synchronized interannual variability with a 2 - to 3-year period of the Kuroshio strength and position in the ECS during 2005–2016. However, as reported by our previous study, the sea surface height anomaly advected from the North Equatorial Current zone to the ECS played a crucial role in the Kuroshio variability in the ECS during 1995–2005. Finally, we noticed that the water interaction between the Kuroshio and continental shelf was strengthened when the Kuroshio was weakened and shifted inshore; more Kuroshio's water flowed onto the continental shelf, which warmed and salted the water in the area from the northern ECS to the southern Japan Sea.