The mean properties and variations of the Southern Hemisphere subpolar gyres estimated by Simple Ocean Data Assimilation (SODA) products
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摘要: 本文基于SODA数据集研究了南半球亚极地流涡的平均特征及其变化性。SODA结果评估三个亚极地流涡的强度分别为Weddell流涡(55.9±9.8)×106m3/s,Ross流涡(37.0±6.4)×106m3/s,Australian-Antarctic流涡(27.5±8.2)×106 m3/s。相邻的两个流涡间存在显著的内在联通性,从而在南半球亚极地海域形成了一个海洋超级流涡结构。其内部的水体交换在70E为(8.0±3.2)×106m3/s,在140E为(4.3±3.1)×106m3/s。三个亚极地流涡最显著的变化集中在季节时间尺度上,都表现为冬季强,夏季弱。流涡结构的季节变化表现为Weddell流涡与Australian-Antarctic流涡的东边界在冬季向东延伸的更远,从而使得超级流涡间的水体交换增加。另外,Weddell流涡与Ross流涡也表现出较强的半年周期变化。相关性分析确认了流涡强度变化与局地风场强迫间的紧密联系。Abstract: Based on the Simple Ocean Data Assimilation (SODA) products, we study the mean properties and variations of the Southern Hemisphere subpolar gyres (SHSGs) in this paper. The results show that the gyre strengths in the SODA estimates are (55.9±9.8)×106 m3/s for the Weddell Gyre (WG), (37.0±6.4)×106 m3/s for the Ross Gyre (RG), and (27.5±8.2)×106 m3/s for the Australian-Antarctic Gyre (AG), respectively. There exists distinct connectivity between the adjacent gyres and then forms an oceanic super gyre structure in the southern subpolar oceans. And the interior exchanges are about (8.0±3.2)×106 m3/s at around 70°E and (4.3±3.1)×106 m3/s at around 140°E. The most pronounced variation for all three SHSGs occurs on the seasonal time scale, with generally stronger (weaker) SHSGs during austral winter (summer). And the seasonal changes of the gyre structures show that the eastern boundary of the WG and AG extends considerably further east during winter and the interior exchange in the super gyre structure increases accordingly. The WG and RG also show significant semi-annual changes. The correlation analyses confirm that the variations of the gyre strengths are strongly correlated with the changes in the local wind forcing on the semi-annual and seasonal time scales.
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Key words:
- the subpolar gyres /
- Southern Ocean /
- wind stress /
- wind stress curl
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