The interannual variability of the eddy kinetic energy (EKE) east of the Luzon-Taiwan Islands is examined using an eddy-resolving (1/12º) reanalysis data set. The underlying mechanisms are investigated with an energetics analysis method. Generally, the interannual signal of EKE in the Northwestern Pacific Subtropical Countercurrent (STCC) region correlates well with the Philippines-Taiwan Oscillation (PTO) index. Different from the ocean interior (OI) where the interannual variability of the EKE is determined by the baroclinic instability (BCI), the interannual variation of EKE along the Kuroshio Current (KC) east of the Luzon-Taiwan Islands is governed by the mixed barotropic-baroclinic instabilities. In particular, during the years 2012-2013 when the EKE in the OI is attenuated by the BCI, the EKE along the KC east of the Luzon (Taiwan) Island is enhanced (weakened) by the barotropic instability (BTI) and the EKE to the east of the KC is strengthened by the BTI and BCI simultaneously.

eddy kinetic energy,interannual variability