Generation of a trigger meander for the 2004 Kuroshio large meander
Generation of a trigger meander for the 2004 Kuroshio large meander
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DOI：
10.1029/2007jc004266
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发表时间：
2008
影响因子：
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通讯作者：
N. Usui;H. Tsujino;Y. Fujii;M. Kamachi
中科院分区：
文献类型：
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作者：
N. Usui;H. Tsujino;Y. Fujii;M. Kamachi
[1]利用海洋资料同化和预报系统研究了2004年九州东南部一个小弯曲的生成过程，该过程引发了随后的黑潮大弯曲。同化结果表明，小曲流是1993年以来最发育的曲流。黑潮环流（KR）向西传播的气旋性涡旋和伴随高位涡（高PV）异常的东海扰动对小弯曲的形成起着重要作用。气旋涡流触发了九州东南部的初始气旋异常。当高位涡异常通过吐噶喇海峡时，由于水柱的拉伸作用增强，产生了较大的正涡度。正涡度是由气旋性异常带进来的，并在那里积累。结果，产生了小的弯曲。从两个敏感性实验的一个发生条件是确定的气旋涡从KR触发初始的小尺度弯曲，和来自ECS的扰动有助于小弯曲的水平尺度。将扰动进一步追溯到黑潮上游，发现扰动是台湾以东强反气旋涡旋与黑潮碰撞产生的水平尺度较大的锋面波。锋面波沿着黑潮传播，伴随着陆架边缘附近粘性产生的高PV。因此，大的锋面波可以通过将大量的高PV异常输送到吐噶喇海峡来促进触发曲流的形成。
[1] A generation process of a small meander southeast of Kyushu, which triggered the subsequent Kuroshio large meander in 2004, has been investigated using an ocean data assimilation and prediction system. The assimilation result reveals that the small meander is the most developed one since 1993. A cyclonic eddy propagating westward from the Kuroshio recirculation (KR) and a disturbance from the East China Sea (ESC) that accompanies a high potential vorticity (high-PV) anomaly play important roles for the generation of the small meander. The cyclonic eddy triggers an initial cyclonic anomaly southeast of Kyushu. When the high-PV anomaly passes through the Tokara Strait, a large positive vorticity is generated because the stretching of the water column is enhanced. The positive vorticity is brought in the cyclonic anomaly and accumulates there. As a result, the small meander is generated. From two sensitivity experiments an occurrence condition is determined by the cyclonic eddy from the KR by triggering the initial small-scale meander, and the disturbance from the ECS contributes to the horizontal scale of the small meander. Tracing back the disturbance further to the upstream region of the Kuroshio, it is revealed that the disturbance is a frontal wave with a large horizontal scale generated by collision between a strong anticyclonic eddy and the Kuroshio east of Taiwan. The frontal wave propagates along the Kuroshio accompanying high-PV generated around the continental shelf edge by viscosity. Thus the large frontal wave could contribute to the generation of the developed trigger meander by transporting a larger amount of high-PV anomaly to the Tokara Strait.