Mean field and annual variation of surface flow in the East China Sea as revealed by combining satellite altimeter and drifter data
Mean field and annual variation of surface flow in the East China Sea as revealed by combining satellite altimeter and drifter data
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DOI：
10.1016/j.pocean.2013.01.007
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发表时间：
2013-04
影响因子：
4.1
通讯作者：
Daisuke Takahashi;A. Morimoto
中科院分区：
文献类型：
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作者：
Daisuke Takahashi;A. Morimoto
利用卫星高度计和漂流仪资料对东海表层流场进行了分析，得到了东海表层流场的平均场和年际变化的综合信息。台湾暖流、陆上黑潮入侵、黑潮、东北黑潮分支、九州以西的北向流、济州暖流和对马暖流被认为是持续流。年变化是ECS中的主导信号，也是季节变化的主要组成部分。在东海，年变化对季节变化的贡献约为50%，而台湾东北黑潮、台湾暖流、台湾海峡暖流、黑潮入侵、东北黑潮分支、九州以西的北上流和对马暖流的年变化对季节变化的贡献超过70%。年变化的特征是台湾海峡东北部和对马海峡涡度异常的传播。来自台湾海峡东北部的涡度异常在东北向黑潮分支中沿沿着约100 m的等深线向下游传播。对马海峡的涡度异常则沿沿着等深线向对马暖流上游传播。涡度异常的传播导致东北向黑潮分支和九州以西的北向海流出现位相差的年变化，这种涡度异常的行为可以用准地转地形Rossby波在平均流中传播的频散关系作一级近似解释。台湾海峡东北部和对马海峡涡度异常的产生分别与台湾东北部黑潮流速和对马海峡流量的年变化密切相关。
An analysis of a surface flow field in the East China Sea (ECS) obtained by combining satellite altimeter and drifter data provides comprehensive information of its mean field and annual variation. The Taiwan Warm Current, the onshore Kuroshio intrusion, the Kuroshio, the northeastward Kuroshio branch, the northward current west of Kyushu, the Cheju Warm Current, and the Tsushima Warm Current are regarded as persistent currents. Annual variation is a dominant signal in the ECS and is a major component of the seasonal variation. The contribution of the annual variation to the seasonal variation is estimated as 50% over the ECS, and exceeds 70% for the Kuroshio northeast of Taiwan, the Taiwan Warm Current, the Taiwan Strait Warm Current, the onshore Kuroshio intrusion, the northeastward Kuroshio branch, the northward current west of Kyushu, and the Tsushima Warm Current. The annual variation is characterized by propagation of vorticity anomalies from northeast of the Taiwan Strait and in the Tsushima Strait. The vorticity anomaly from northeast of the Taiwan Strait propagates downstream in the northeastward Kuroshio branch along isobaths of about 100m on the shelf edge. In contrast, the vorticity anomaly in the Tsushima Strait propagates upstream of the Tsushima Warm Current along isobaths of 100–200m. The propagation of the vorticity anomalies causes the annual variation with a phase difference in the northeastward Kuroshio branch and the northward current west of Kyushu, and the behavior of the vorticity anomalies can be well explained as a first approximation by a dispersion relation of a quasigeostrophic topographic Rossby wave propagating in a mean flow. Generation of the vorticity anomalies from northeast of the Taiwan Strait and in the Tsushima Strait appears to be closely related to the annual variation of the Kuroshio’s current speed northeast of Taiwan and of volume transport through the Tsushima Strait, respectively.