Numerical study on the Kuroshio path states in the northern Okinawa Trough of the East China Sea
Numerical study on the Kuroshio path states in the northern Okinawa Trough of the East China Sea
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DOI：
10.1029/2004jc002656
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发表时间：
2005-04-08
影响因子：
3.6
通讯作者：
Nakamura, H
中科院分区：
文献类型：
--
作者：
Nakamura, H
冲绳海槽北方黑潮具有准双峰型特征，存在明显的北方和南方路径状态。黑潮路径状态在这里检查通过模拟使用原始的流入/流出模型的16个流入结构参数化的最大表面速度的位置和速度随深度的下降率。模拟结果表明，冲绳海槽北方存在三种不同的路径状态：一种弱稳定的北方路径状态与反气旋性黑潮弯曲的阻塞有关，一种高度稳定的南方路径状态与气旋性黑潮弯曲的阻塞有关，以及一种中等不稳定的路径状态。在不稳定状态的变化，发生在北方和南方的路径状态或周期性波动，否则稳定的路径之间的周期性过渡，驱动的自我持续的内部振荡在北方冲绳海槽。斜压不稳定引起的陆坡区气旋生成对不稳定状态下黑潮路径的变化起着重要作用，这种不稳定性有效地受控于黑潮平均路径在陆坡上的位置，而不是通常认为的黑潮平均路径的速度。
Previous observations have indicated that the Kuroshio in the northern Okinawa Trough is quasibimodal in character, with distinct northern and southern path states. The Kuroshio path states are examined here through simulations using a primitive inflow/outflow model for 16 inflow structures parameterized by the location of maximum surface velocity and the rate of velocity decrease with depth. The simulations reveal three distinct path states in the northern Okinawa Trough: a weakly stable northern path state associated with blocking of an anticyclonic Kuroshio meander, a highly stable southern path state maintained by blocking of a cyclonic Kuroshio meander, and an intermediate unstable path state. The variations in the unstable state, occurring as either periodic transitions between the northern and southern path states or periodic fluctuations of an otherwise stable path, are driven by self-sustained internal oscillation in the northern Okinawa Trough. Cyclogenesis in the continental slope area due to baroclinic instability appears to play an important role in Kuroshio path variations in the unstable state, and this instability is effectively controlled by the location of the Kuroshio mean path on the slope rather than its velocity as conventionally thought.