Variation of the Kuroshio in the Tokara Strait Induced by Meso-Scale Eddies
Variation of the Kuroshio in the Tokara Strait Induced by Meso-Scale Eddies
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DOI：
10.1023/a:1011174720390
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发表时间：
2001-06
影响因子：
2.3
通讯作者：
K. Ichikawa
中科院分区：
文献类型：
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作者：
K. Ichikawa
在TOPEX/POSEIDON和ERS-1第一级联期间(1992年10月至1993年12月)，用高分辨率海面动力地形(SSDT)场的位相传播复数EOF模分解了托卡拉海峡和明日香线黑潮体积输送的时间变化。这两种变化都以近半年周期的模式为主，表明黑潮与中尺度涡旋之间存在着一系列相互作用。也就是说，23°N向西传播的中尺度涡旋的北部被捕获到冲绳南部黑潮的南侧，然后沿着通过托卡拉海峡的黑潮路径向下移动，到达明日香线，在那里它与另一个从东面传播的30°N涡旋汇合。明日香线上的变化不太受这种模式的支配，而是包括了四国南部和九州以东的SSDT变化，这些变化将直接受到来自东部的涡流的影响，而不是通过托卡拉海峡。另一方面，对海峡黑潮轴线运动的分析表明，黑潮轴线的运动是由局限于东中国海黑潮的短期变化所控制的，而不是由中尺度涡旋引起的。然而，这一结果似乎很大程度上取决于人们感兴趣的时间尺度。结果表明，黑潮轴线在海峡的长期运动与日本南部的SSDT变化相吻合。
Temporal variations of the Kuroshio volume transport in the Tokara Strait and at the ASUKA line are decomposed by phase-propagating Complex EOF modes of high-resolution sea surface dynamic topography (SSDT) field during the first tandem period of TOPEX/POSEIDON and ERS-1 (from October 1992 to December 1993). Both variations are dominated by a mode with nearly semi-annual cycle, which indicates a series of interactions between the Kuroshio and meso-scale eddies. Namely, northern part of a westward-propagating meso-scale eddy at 23°N is captured into the southern side of the Kuroshio at the south of Okinawa, then it moves downstream along the Kuroshio path passing the Tokara Strait, and reaches to the ASUKA line where it merges with another eddy propagating from the east at 30°N. The variation at the ASUKA line is, however, less dominated by this mode; instead, it includes the SSDT variations in the south of Shikoku and the east of Kyushu which would be directly affected by eddies from the east without passing the Tokara Strait. On the other hand, the same analysis for movements of the Kuroshio axis in the Strait indicates that they are governed by short-term variations locally confined to the Kuroshio in the East China Sea without being induced by meso-scale eddies. This results, however, seem to depend strongly on a time scale of interest. It is suggested that the long-term movements of the Kuroshio axis in the Strait would demonstrate coincidence with SSDT variation in the south of Japan.