Eddy-Kuroshio Interactions: Local and Remote Effects
Eddy-Kuroshio Interactions: Local and Remote Effects
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DOI：
10.1002/2017jc013476
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发表时间：
2017-12-01
影响因子：
3.6
通讯作者：
Yang, Yiing Jang
中科院分区：
文献类型：
--
作者：
Jan, Sen;Mensah, Vigan;Yang, Yiing Jang
准地转中尺度涡旋在北太平洋西部定期冲击黑潮，但这些涡旋-黑潮相互作用的演变过程尚未在文献中得到彻底的研究。在这里，这种相互作用的研究结果，从一个半理想化的三维数值模式和观测，从四个压力传感器配备的倒置回声测深仪（PIES）在台湾东部的纬向剖面和卫星高度计。观测和数值模拟结果均表明，在气旋性涡旋与黑潮相互作用过程中，圆形涡旋在消散前变形为长轴为西北-东南方向的椭圆形，黑潮向极运动速度和黑潮输运减小，黑潮两侧的海平面和密度跃层斜率减弱。相反，对于反气旋涡在涡黑潮相互作用，速度，海平面和等密度线深度的变化是相反的，圆形涡也变形为椭圆形，但与黑潮的主轴平行。模拟结果还表明，在相互作用过程中，速度场首先被修正，因此SSH和等密度线深度也随之演变。此外，由于撞击纬度和实际地形的共同作用，在吕宋海峡和台湾东北部东海陆架，台湾以东的一些涡旋-黑潮相互作用具有远程效应。这些直径约为100-300 km、绕流速度约为0.5 m/s的顺时针或逆时针旋转的海洋漩涡携带能量和某种类型的水团向西运动，最终到达各大洋的西边界。这些涡旋的演变以及它们遇到西边界流（如北太平洋西部的黑潮）时发生的相互作用，对于重新分配海洋能量，进而形成大尺度海洋环流具有重要意义。本研究主要探讨非线性中尺度涡旋与黑潮相互作用的过程，这在文献中尚未被深入研究。利用配备压力传感器的回声测深仪和在半理想化数值模拟背景下解释的卫星观测，本研究发现：（1）在本地，涡旋到达首先改变黑潮的速度结构，然后是海平面和等密度线深度的变化，导致黑潮的海平面和密度斜率的跷跷板式变化;（2）模拟的远程效应，即，黑潮入侵，出现在吕宋海峡和东海陆架，并取决于涡旋的冲击纬度，强度和极性。
Quasi-geostrophic mesoscale eddies regularly impinge on the Kuroshio in the western North Pacific, but the processes underlying the evolution of these eddy-Kuroshio interactions have not yet been thoroughly investigated in the literature. Here this interaction is examined with results from a semi-idealized three-dimensional numerical model and observations from four pressure-sensor equipped inverted echo sounders (PIESs) in a zonal section east of Taiwan and satellite altimeters. Both the observations and numerical simulations suggest that, during the interaction of a cyclonic eddy with the Kuroshio, the circular eddy is deformed into an elliptic shape with the major axis in the northwest-southeast direction, before being dissipated; the poleward velocity and associated Kuroshio transport decrease and the sea level and pycnocline slopes across the Kuroshio weaken. In contrast, for an anticyclonic eddy during the eddy-Kuroshio interaction, variations in the velocity, sea level, and isopycnal depth are reversed; the circular eddy is also deformed to an ellipse but with the major axis parallel to the Kuroshio. The model results also demonstrate that the velocity field is modified first and consequently the SSH and isopycnal depth evolve during the interaction. Furthermore, due to the combined effect of impingement latitude and realistic topography, some eddy-Kuroshio interactions east of Taiwan are found to have remote effects, both in the Luzon Strait and on the East China Sea shelf northeast of Taiwan.Plain Language Summary Mesoscale eddies are everywhere in the ocean. These ocean swirls of either clockwise or counterclockwise spinning with diameter of about 100-300 km and rounding current speed of about 0.5 m/s, carrying energy and certain type of water mass, move westward and eventually reach the western boundary of each ocean. The evolution of these eddies and the interaction which occurs when they encounter the western boundary current, e.g. the Kuroshio in the western North Pacific, is important in redistributing ocean energy and, in turn, shaping the large scale ocean circulation. This study focuses on the processes underlying the interaction of nonlinear mesoscale eddies with the Kuroshio, which have not yet been thoroughly investigated in the literature. Using pressure-sensor equipped echo sounder and satellite observations interpreted in the context of semi-idealized numerical simulations, this study find (1) locally, eddy arrivals modify velocity structure in the Kuroshio first, followed by changes in sea level and isopycnal depths leading to seesaw-like variations of the sea level and density slopes across the Kuroshio, and (2) modeled remote effects, i.e., Kuroshio intrusions, manifest in the Luzon Strait and on the East China Sea shelf and depend on the eddies' impingement latitude, strength, and polarity.