Seasonality of the Kuroshio Intensity East of Taiwan Modulated by Mesoscale Eddies

Abstract The intensity of the Kuroshio Current east of Taiwan shows a clear seasonality, and the Kuroshio is affected by mesoscale eddies east of Taiwan. Sea surface geostrophic velocity and mesoscale eddies derived from satellite altimeter data and gridded Argo-only geostrophic velocity data were used to analyze the mesoscale eddy contribution to the Kuroshio intensity seasonality in the East Taiwan Channel. The low potential vorticity water stacked at the northern side of the subtropical countercurrent (STCC) and eddy generation favored the cyclonic eddy. Between August and January, the STCC near the western boundary area (125°E-135°E) showed two branches and a significant negative zonal velocity meridional gradient between 19°N and 21°N from October to December, which led to a higher occurrence of cyclonic eddies. These eddies reached the area east of Taiwan in 100 days and resulted in the dominance of cyclonic eddies between January and April and a weakened Kuroshio Current.