Tidal and residual currents across the northern Ryukyu Island chain observed by ferryboat ADCP
Tidal and residual currents across the northern Ryukyu Island chain observed by ferryboat ADCP
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ADCP渡船观测琉球岛北部链的潮汐和余流
DOI：
10.1002/2017jc012876
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发表时间：
2017
影响因子：
3.6
通讯作者：
Dong Menghong
中科院分区：
文献类型：
--
作者：
Liu Zhao Jun;Nakamura Hirohiko;Zhu Xiao Hua;Nishina Ayako;Dong Menghong
利用2003 - 2012年的渡船声学多普勒海流剖面仪（ADCP）资料，对冲绳和奄美大岛之间的北方琉球岛链（RIC）的潮流和余流进行了估算。在该海域，M2潮流是最强的分潮，K1潮流是最强的日分潮。相应的最大振幅分别为40和34 cm s-1。去除潮流后，平均体积输运量为1.5 ± 2.7Sv，从北太平洋西部经该海域4条通道进入东海。在一个经验正交函数（ERF）分析，以澄清通过四个通道的电流的时间和空间变异性，前两个ERF模式占总方差的71%和18%，分别。EOF 1模态在深槽中表现出明显的底部增强模态，可能是由向西传播的中尺度涡旋撞击北方RIC东侧斜坡而形成的底陷长地形Rossby波传播形成的。EOF 2模态具有明显的季节变化，可能是由北方RIC附近黑潮流区10 - 11月盛行的风应力驱动的。本研究为建立北太平洋副热带西边界环流方案提供了北方RIC水交换的观测证据。
Ferryboat Acoustic Doppler Current Profiler (ADCP) data from 2003 to 2012 are used to estimate the tidal and residual currents across the northern Ryukyu Island chain (RIC) between the islands of Okinawa and Amamioshima. In this region, the M2 tide current is the strongest tidal component, and the K1 tide current is the strongest diurnal tidal component. The corresponding maximum amplitudes are 40 and 34 cm s−1, respectively. After removal of the tidal currents, the mean volume transport, 1.5 ± 2.7 Sv, flows into the East China Sea (ECS) from the western North Pacific through four channels in this area. In an empirical orthogonal function (EOF) analysis performed to clarify the temporal and spatial variability of currents through the four channels, the first two EOF modes account for 71% and 18% of the total variance, respectively. The EOF1 mode shows a clear bottom-intensified mode through the deep channel, which is likely to be formed by the propagation of bottom-trapped long topographic Rossby wave caused by the impingement of westward propagating mesoscale eddies upon the eastern slope of the northern RIC. The EOF2 mode has significant seasonal variability and may be driven by the wind stress prevailing over the Kuroshio flow region around the northern RIC in October to November. This study provides observational evidence of the water exchanges across the northern RIC, which is essential for constructing a circulation scheme in the North Pacific subtropical western boundary region.