Climatic Controls on the Interannual Variability of Shelf Circulation in the Northern South China Sea
Climatic Controls on the Interannual Variability of Shelf Circulation in the Northern South China Sea
复制标题
气候对南海北部陆架环流年际变化的控制
DOI：
10.1029/2022jc018419
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发表时间：
2022-06
影响因子：
3.6
通讯作者：
Zhongya Cai
中科院分区：
文献类型：
--
作者：
Yongfei Deng;Zhiqiang Liu;Tingting Zu;Jianyu Hu;Jianping Gan;Yuxin Lin;Zhibing Li;Qi Quan;Zhongya Cai
基于观测资料和数值模拟，全面研究了1994-2018年南海北部多尺度运动的年际变化以及陆地、大气和海洋过程的相关影响。研究发现，以El Niño-Southern涛动（ENSO）为代表的热带气候变率对NSCS环流和水文特征的年际变化较为敏感，表现为一个跨尺度的交互动力系统。在水深小于30 m的沿海地区，El Niño （La Niña）年珠江流域以降水（蒸发）和正（负）热通量异常为主，其异常的暖（冷）和少（多）盐水受珠江流量的调节。在坡流和大气强迫的年际变化控制下，30 ~ 200 m陆架流对ENSO的响应不对称，El Niño年东北向流异常强于La Niña年西南向流异常。进一步表明，坡流的年际变化是由大气过程和海洋过程共同控制的，这两个过程在年际时间尺度上趋于相互抵消。特别地，海盆上的气旋性风应力旋度减弱（增强）倾向于缓和（强化）NSCS的斜坡流，而El Niño （La Niña）年的强（弱）黑潮入侵则减轻了这一过程。
We comprehensively investigate the interannual variability of multi-scale motions in the northern South China Sea (NSCS) and associated influences from the terrestrial, atmospheric, and oceanic processes over the period 1994–2018 based on observations and a numerical simulation. We find that the interannual variabilities of the NSCS circulation and hydrographic properties, in the form of a cross-scale interactive dynamic system, are sensitive to the tropical climate variability represented by the El Niño–Southern Oscillation (ENSO). In coastal areas with less than 30 m depth, the anomalous warm (cold) and less (more) saline waters are regulated by the rate of Pearl River discharge due to the predominant precipitation (evaporation) and positive (negative) heat-flux anomaly in the Pearl River catchment in El Niño (La Niña) years. Controlled by the interannual variabilities of slope current and atmospheric forcings, the shelf current at 30–200 m depth responds asymmetrically to the ENSO, which establishes a stronger northeastward flow anomaly in El Niño years than the southwestward flow anomaly in La Niña years. We further show that the interannual variability of the slope current is jointly governed by the atmospheric and oceanic processes that tend to offset each other in interannual timescales. In particular, the weakened (strengthened) cyclonic wind stress curl over the ocean basin tends to moderate (intensify) the slope current in the NSCS, while this process is mitigated by the stronger (weaker) Kuroshio intrusion in El Niño (La Niña) years.