Study on the interannual variability of the Kerama Gap transport and its relation to the Kuroshio/Ryukyu Current system  

作　　者：Han Zhou Kai Yu Jianhuang Qin Xuhua Cheng Meixiang Chen Changming Dong 

机构地区：[1]Key Laboratory of Marine Hazards Forecasting,Ministry of Natural Resources,Hohai University,Nanjing 210003,China [2]College of Oceanography,Hohai University,Nanjing 210003,China [3]School of Marine Sciences,Nanjing University of Information Science and Technology,Nanjing 211800,China

出　　处：《Acta Oceanologica Sinica》2024年第3期1-14,共14页海洋学报（英文版）

基　　金：The Fundamental Research Funds for the Central Universities under contract No.B220201024.

摘　　要：An analysis of a 68-year monthly hindcast output from an eddy-resolving ocean general circulation model reveals the relationship between the interannual variability of the Kerama Gap transport(KGT)and the Kuroshio/Ryukyu Current system.The study found a significant difference in the interannual variability of the upstream and downstream transports of the East China Sea-(ECS-)Kuroshio and the Ryukyu Current.The interannual variability of the KGT was found to be of paramount importance in causing the differences between the upstream and downstream ECS-Kuroshio.Additionally,it contributed approximately 37%to the variability of the Ryukyu Current.The interannual variability of the KGT was well described by a two-layer rotating hydraulic theory.It was dominated by its subsurface-intensified flow core,and the upper layer transport made a weaker negative contribution to the total KGT.The subsurface flow core was found to be mainly driven by the subsurface pressure head across the Kerama Gap,and the pressure head was further dominated by the subsurface density anomalies on the Pacific side.These density anomalies could be traced back to the eastern open ocean,and their propagation speed was estimated to be about 7.4 km/d,which is consistent with the speed of the local first-order baroclinic Rossby wave.When the negative(positive)density anomaly signal reached the southern region of the Kerama Gap,it triggered the increase(decrease)of the KGT towards the Pacific side and the formation of an anticyclonic(cyclonic)vortex by baroclinic adjustment.Meanwhile,there is an increase(decrease)in the upstream transport of the entire Kuroshio/Ryukyu Current system and an offshore flow that decreases(increases)the downstream Ryukyu Current.

关 键 词：Kerama Gap KUROSHIO Ryukyu Current OGCM for the Earth Simulator(OFES) hydraulic theory 

分 类 号：P731.27[天文地球—海洋科学]