Asymmetry of upper ocean salinity response to the Indian Ocean dipole events as seen from ECCO simulation
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摘要: 本文利用海洋观测资料和全球海洋环流模式数据(Estimating the Circulation and Climate of the Ocean, ECCO)研究了赤道印度洋上层海洋盐度的年际变化及其相关的海洋动力过程。研究结果表明,上层海洋盐度年际变化主要受印度洋偶极子事件影响,且盐度变化在正、负印度洋偶极子事件中存在不对称特征,其在偶极子正事件中表现更强烈。进一步研究表明,赤道印度洋上层盐度变化主要受纬向平流输运调控,尤其是Wyrtki急流对盐度变化有重要影响。在正印度洋偶极子事件期间,Wyrkti急流减弱甚至消失,流场负异常的强度明显较负偶极子事件期间的流场正异常强度强。印度洋偶极子存在正偏度是造成盐度和流场在正、负印度洋偶极子事件中存在不对称性的主要原因。Abstract: The interannual variability of salinity and associated ocean dynamics in the equatorial Indian Ocean is analyzed using observations and numerical simulations by the Estimating the Circulation and Climate of the Ocean (ECCO) model. The results show that salinity anomalies in the upper ocean are asymmetrically associated with the Indian Ocean dipole (IOD) events, with stronger response during their positive phases. Further investigations reveal that zonal currents along the equator, the Wyrtki jets, dominate the salinity transport. During the positive IOD events, the Wyrtki jets have stronger westward anomalies. The positive skewness of the IOD explains that the amplitude of the anomalous Wyrtki jets is stronger in the positive IOD events than that in the negative events.
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Key words:
- Wyrtki jets /
- salinity transport /
- Indian Ocean dipole /
- asymmetry
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