Effects of stretching on maintaining the Kuroshio meander
Effects of stretching on maintaining the Kuroshio meander
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DOI：
10.1002/jgrc.20123
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发表时间：
2013-03
影响因子：
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通讯作者：
Masao Kurogi;H. Hasumi;Yukio Tanaka
中科院分区：
文献类型：
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作者：
Masao Kurogi;H. Hasumi;Yukio Tanaka
[1]利用一个双向嵌套网格海洋环流模式，通过改变风强迫强度，研究了黑潮路径的变化。对于气候或弱10%的风强迫，大曲流（LM）和非大曲流（NLM）路径交替出现，每种类型的路径持续几年到十年。这种时间尺度和路径转换过程与观测结果基本一致。对于LM路径，在深度积分涡度方程的上层海洋的主要平衡被证明是之间的β，平流，拉伸条款。在曲流区西侧，拉伸项与β项的大小相当且同号，表明拉伸项具有缩短波长和稳定LM路径的作用，拉伸项主要是由上层流和深层流交叉产生的下沉流决定的。与上述两种情况相反，只有NLM路径出现10%的风强迫。这表明，气候风强迫的强度接近的上限，允许LM路径发生。在本研究中，控制实验是通过选择参数化和参数值来尽可能真实地再现黑潮路径变化。因此，从两个敏感性实验的结果，预计代表一个现实的黑潮路径变化的响应。
[1] Using a two-way nested-grid ocean general circulation model driven by a repeat annual cycle forcing, the Kuroshio path variation is examined by varying the strength of wind forcing. For climatological or 10% weaker wind forcing, both large-meander (LM) and non-large-meander (NLM) paths alternately appear, with each type of path continuing for a few years to a decade. This timescale and path transition processes are generally consistent with observations. For the LM path, the main balance in the depth-integrated vorticity equation for the upper ocean is shown to be between the beta, advection, and stretching terms. The stretching term is comparable to and has the same sign as the beta term at the western side of the meandering part, indicating that the stretching term has the effects of shortening the wavelength and stabilizing the LM path. The stretching term is mainly determined by downwelling caused by crossing of the upper and deep flows. Contrary to the above two cases, only the NLM path appears for 10% stronger wind forcing. It is suggested that the strength of climatological wind forcing is near the upper limit that allows the LM path to occur. In this study, the control experiment is carried out by choosing parameterizations and parameter values to reproduce the Kuroshio path variation as realistic as possible. Therefore, the results from the two sensitivity experiments are expected to represent a realistic response of the Kuroshio path variation.