Long-term variability of the Kuroshio transport east of Taiwan and the climate it conveys

Abstract

The Kuroshio transport (KT) was established using satellite altimetry data from 1993 to 2010 via three methods: the geostrophic relationship (GR), the empirical relationship (ER), and the transfer function (TF). The relationships were built on the observed KT from the World Ocean Circulation Experiment moored current meter array east of Taiwan (referred to as PCM-1) and its surrounding sea surface height (SSH) difference. Using a modeled 10-year climatology run of the KT, we verify the three methods and associated characteristics in long-term applications. The GR could not capture high-frequency variability of less than four months well. The KT approximated by the ER had a similar variation with a weaker magnitude and the transport was underestimated. Although the TF can establish signals from all available frequency domains, results suggest that the observational period of PCM-1 may be too short to build a reliable TF. The KT estimated by both the GR and the TR was subsequently used to analyze the long-term variability of the KT in the PCM-1 line. The annual averaged KT was influenced by the northern branch of the North Equatorial Current that was affected primarily by El Niño-Southern Oscillation events. The anomaly of the KT was dominated by mesoscale eddies east of Taiwan resulting from the influence of the West Pacific (WP) teleconnection pattern. Correlation analysis confirmed that the long-term KT in the PCM-1 line conveys not only the ENSO signal but the WP teleconnection, which connects the tropic and extratropic dynamics together.