Effects of mesoscale eddies on the volume transport and branch pattern of the Kuroshio east of Taiwan

Abstract

Using satellite altimeter data and a long-term altimetric transport index for the Kuroshio inflow northeast of Taiwan, the effects of mesoscale eddies on the Kuroshio volume transport (KVT) at the East Taiwan Channel and the branching pattern of the Kuroshio east of Taiwan are investigated at scales from those of individual events to interannual timescales. Both anticyclonic and cyclonic eddies are found to be able either to strengthen or weaken the KVT, depending on the relative strength of mass convergence and divergence produced upstream and downstream of the eddies. The major factor influencing the intensity of the Kuroshio inflow is the meridional location of the eddies. For single eddy events, the KVT is significantly correlated with the latitude of the eddy's center, the correlations being 0.44 and −0.48 for anticyclonic and cyclonic eddies, respectively. For dipole eddy events, when the direction angle falls in the interval 40–150° (240–300°), the KVT anomaly tends to be positive (negative). Furthermore, low KVT events generally correspond to the formation of the Ryukyu Current branch, which is also generated from strong mass divergence produced by the eddies. In addition, on interannual timescales, the variation of KVT is closely related to the relative number of anticyclonic to cyclonic eddies west of 125°E, with a correlation of 0.5.