Dynamics of Kuroshio path variations in a high-resolution general circulation model
Dynamics of Kuroshio path variations in a high-resolution general circulation model
复制标题
DOI：
10.1029/2005jc003118
复制
发表时间：
2006-11
影响因子：
--
通讯作者：
H. Tsujino;N. Usui;H. Nakano
中科院分区：
文献类型：
--
作者：
H. Tsujino;N. Usui;H. Nakano
[1]利用高分辨率大气环流模式（GCM）模拟了黑潮的一个典型大弯曲路径，研究了黑潮大弯曲路径的形成、维持和消失过程。LM的形成是由黑潮上层的一对反气旋性涡旋和气旋性涡旋触发的，其中气旋性涡旋位于下游侧。在到达日本南部四国盆地的西侧时，这些异常引起低层反气旋涡流。它们在被黑潮带向东的过程中相互增强。具体来说，低层反气旋涡旋东侧的南向气流将上层冷气旋涡旋带到离岸，导致黑潮路径向南偏转（大弯曲）。这些过程可以理解为斜压不稳定的增长。当黑潮路径弯曲引起的平流和涡诱导共同作用所产生的东移抵消了大纬向位移引起的β效应所产生的西移趋势时，就建立了一个定常的LM，而来自上游的大尺度扰动则通过斜压能量转换加强了LM。相反，来自上游的小尺度扰动通过斜压能量转换，沿着弯曲的黑潮锋面局部增长。当它们向东流动时，它们从LM的冷气旋涡流中提取冷沃茨。冷气旋涡旋的水平范围减小，并且由于平流效应超过β效应而使弯曲向东移动，β效应由于较小的平流范围而减弱。
[1] A long-lived (2-year) typical large meander (LM) path of the Kuroshio is reproduced in a high-resolution general circulation model (GCM) simulation with realistic topography, and the life cycle (formation, maintenance, and disappearance) of the LM is studied. The formation of the LM is triggered by a pair of upper layer anticyclonic and cyclonic eddies on the Kuroshio, with the cyclonic one on the downstream side. Upon reaching the western side of the Shikoku Basin south of Japan these anomalies induce a lower layer anticyclonic eddy. They enhance each other while they are carried eastward by the Kuroshio. Specifically, the southward flow on the eastern side of the lower anticyclonic eddy carries the upper cold cyclonic eddy offshore, resulting in the southward deflection of the Kuroshio path (large meander). These processes can be understood as a growth of baroclinic instability. A stationary LM is established when the westward tendency, caused by the beta effect owing to the large meridional displacement, counterbalances the eastward tendency, caused by the combination of advection and vortex induction owing to the curvature of the Kuroshio path. Large-scale disturbances from the upstream tend to strengthen the LM through baroclinic energy conversion. In contrast, small-scale disturbances from the upstream grow locally along the meandering Kuroshio front through baroclinic energy conversion. They extract cold waters from the cold cyclonic eddy of the LM as they flow away to the east. The horizontal extent of the cold cyclonic eddy is reduced, and the meander is carried eastward since the advection effect dominates over the beta effect that weakens as a result of the smaller meridional extent.