Study on the variability of the Kuroshio at the entrance into the East China Sea

利用东海中国口的海底电缆电压资料，结合卫星测高资料、漂流表层流资料等，研究了东海入海口黑潮的变化情况，利用长达9年的电缆电压资料可以监测东海口附近黑潮输送下游侧的变化。其他数据显示了表面电流的广泛空间分布等。(1)黑潮输运随台湾东岸上游附近中尺度海洋涡旋的存在而变化。暖(反气旋)涡可以增加输送，冷(气旋性)涡可以减少输送。冷涡的变化比暖涡的大。从东部传播的中尺度涡旋出现得相当随机，每年有几个(2~3)个。由于每个涡旋的生存时间约为几个月(1~3)，因此输送受中尺度涡旋的影响几乎有半年的时间。(2)季节性Var…利用这些资料对入口处周围的输运和流场的更多关系进行了检验。变奏中有两种典型的模式：“冬季模式”和“夏季模式”。冬季(12-3月)，吕宋岛上游黑潮输送增加，部分黑潮通过吕宋海峡进入中国南海，台湾外黑潮输送减少。环流输送的变化不像上游那样大，表现出一定的区域性差异。从ECS经琉球群岛有一些外流到太平洋，这对黑潮的再循环有贡献。在夏季(6月下半月至8月)，吕宋岛外的输送减少，没有进入南海的流量。在ECS中，再循环没有特殊的流出。这些季节变化似乎与风场一致。(3)对与此相关的几项研究进行了尝试：利用横跨黑潮的ECS中连接冲绳和台湾的渡轮服务进行的海面温度观测、ECS中表层Ekman流的资料和模式分析、ECS中受黑潮影响的海面热通量、云和降水的气候学。较少

The variability of the Kuroshio at the entrance into the East China Sea (ECS) is studied mainly using the OKITAI submarine cable voltage data along with satellite altimetry data and drifter-derived surface current data etc. The cable voltage data of about 9 years can monitor the variability of the Kuroshio transport downstream side near the entrance. Other data show wide spatial distributions of surface currents etc. The following results are obtained. (1) The Kuroshio transport varies according to the presence of mesoscale ocean eddies off east coast of Taiwan upstream side. Warm (anti-cyclonic) eddies can increase the transport and cold (cyclonic) eddies decrease the transport. Cold eddies make larger variation than warm eddies. Mesoscale eddies propagating from the east appear rather randomly ; several numbers (2～3) per year. Since the lifetime of each eddy is about several months (1～3), the transport is under the influence of mesoscale eddies almost half of a year. (2) Seasonal var … More iations of the transport and flow field around the entrance are examined using monthly means of these data. There are two typical modes in the variations ; "winter mode" and "summer mode". In winter mode (Dec.-Mar.), the Kuroshio transport upstream side off Luzon increases and some of it flows into the South China Sea (SCS) through the Luzon strait bringing the transport decrease off Taiwan. The variation of the transport in ECS is not so large as that of the upstream side, and shows somewhat regional variation. There is some outflow from ECS to the Pacific Ocean through Ryukyu Islands, which contributes the recirculation to the Kurosho. In summer mode (Jun.last half-Aug.), the transport off Luzon decreases with no flow into SCS. In ECS, there is no special outflow for the recirculation. These seasonal variations seem to be consistent with wind fields. (3) Several studies related to the above are additionally tried ; Sea surface temperature observation using a ferry service connecting Okinawa to Taiwan in ECS crossing the Kuroshio, Data and model analysis of surface Ekman currents in ECS, Climatology of sea surface heat flux, clouds and rain fall under the influence of the Kuroshio in ECS. Less