Inter-annual and decadal fluctuations of the Kuroshio in East China Sea and connection with wind and surface heat flux

Abstract:

Despite various attempts in the literature to link large scale oscillations of wind to long-term variations of the Kuroshio in East China Sea (ECS), the driving mechanism(s) are unknown. Here satellite altimetry data, wind, surface heat fluxes and sea-surface temperatures (SST) are used to analyze the fluctuations of Kuroshio path (KP) along the continental slope of ECS. The dominant EOF explains 44% of the variance, and its spatial pattern is of one sign, but with a concentrated amplitude some 160 km northeast of Taiwan. At the inter-annual periods, KP is found to be best correlated with the PTO index of Chang and Oey [2012, J.Clim], less so with PDO and a Kuroshio transport index, and is poorly correlated with other climate indices. The KP significantly correlates with a wind stress curl dipole along the Kuroshio, as well as with a zonal gradient in surface heat fluxnortheast of Taiwan [Oey et al 2010, Ocean Dyn], both of which are characteristics of the PTO, but not PDO. Over the past 2 decades, the KP has an onshore trend. The shelf’s SST warms and cools in concert with the onshore and offshore paths of the Kuroshio, but the most prominent change occurs at a localized coastal zone immediately shoreward of the EOF’s largest amplitude northeast of Taiwan.