Application of singular vector analysis to the Kuroshio large meander
Application of singular vector analysis to the Kuroshio large meander
复制标题
DOI：
10.1029/2007jc004476
复制
发表时间：
2008-07-19
影响因子：
3.6
通讯作者：
Kamachi, Masafumi
中科院分区：
文献类型：
--
作者：
Fujii, Yosuke;Tsujino, Hiroyuki;Kamachi, Masafumi
奇异矢量分析应用于日本南部黑潮大曲流的形成。我们使用海洋环流模型（OGCM）的模拟运行，其中发生大曲流作为背景状态。奇异向量通过 Lanczos 方法计算，其中使用 OGCM 的切线模型和伴随模型。我们应用增量校正方法来设置初始扰动并平均最终范数，以便通过滤除高频变化来获得反映非线性物理的模式。如果提取为前导右奇异向量的扰动在两个月前设置为背景状态，则对大曲流的形成影响最大。当加上摄动时，会增强九州东南部上层的反气旋涡流，从而诱发其以北的下降流，并在深层发展出反气旋涡流。反气旋涡流在下游边缘产生冷异常，并在那里产生斜压不稳定，导致大曲流进一步发展。相比之下，减去扰动后，深层反气旋涡减弱，深层冷异常发展延迟，导致曲流不那么发育。由此可见，奇异矢量分析揭示了接近九州东南部的反气旋涡在上层的作用，并表明了反气旋涡在深层的重要性。
Singular vector analysis is applied to the formation of the Kuroshio large meander south of Japan. We use a simulation run of an ocean general circulation model (OGCM), in which a large meander occurs, as the background state. Singular vectors are calculated by the Lanczos method in which the tangent linear and adjoint models of the OGCM are used. We apply an incremental correction approach for setting up the initial perturbation and averaging for the final norm in order to get modes reflecting nonlinear physics by filtering out high-frequency variations. The perturbation extracted as the leading right singular vector affects the formation of the large meander most if it is set to the background state two months before. When the perturbation is added, it enhances an anticyclonic eddy southeast of Kyushu in the upper layer, which induces downwelling north of it and develops an anticyclonic eddy in the deep layer. The anticyclonic eddy produces a cold anomaly at the downstream edge, and produces baroclinic instability there, resulting in further development of the large meander. In contrast, the anticyclonic eddy in the deep layer is weakened when the perturbation is subtracted, the development of the cold anomaly in the deep layer is delayed, and consequently the meander is not so well developed. Thus singular vector analysis reveals the role of the anticyclonic eddy approaching southeast of Kyushu in the upper layer, and indicates the importance of the anticyclonic eddy in the deep layer.