Influence of Two Eddy Pairs on High‐Salinity Water Intrusion in the Northern South China Sea During Fall‐Winter 2015/2016

Abstract

AbstractTwo processes of high‐salinity water (≥34.7 psu; HSW) intrusion were recorded by an Argo float in the northeastern South China Sea (SCS) during fall‐winter of 2015/2016. Combined with the satellite altimetry and reanalysis data, the influence of related eddy pairs on HSW transport was investigated. The results show that apart from the Kuroshio‐originated anticyclonic eddy (AE), the localized cyclonic eddy (CE), and the westward jet between the eddy pair all contributed to the HSW transport. In the first process, the effect of eddy trapping accounted for 74% of the HSW transport, while the associated jet accounted for the residual 26%. The contribution of the southern CE was stronger than that of the northern AE. In the second process, the Kuroshio‐originated AE and its southern jet dominated the HSW transport. The westward jet conveyed abundant HSW to the interior SCS before the eddy pair propagated westward, accounting for 52% of HSW transport, while AE accounted for 43% and CE for 5%. Energy analysis showed that barotropic and baroclinic instabilities were important for the generation and growth of the AE in both processes, and CE in the first process was produced by baroclinic instability and wind stress work, while CE in the second process was predominantly triggered by barotropic instability. The development of eddy pairs combined with the SCS interior circulation jointly affected the HSW transport. This study identified the important contributions from two eddy pairs and discussed the effect of interior circulation‐Kuroshio interaction on HSW intrusion in the northern SCS.