南海海表面温度年代际异常变化特征及其与PDO的联系

Decadal variability of SSTA in the South China Sea and its relationship with PDO

利用奇异谱分析和小波分析的方法,分析了南海海表面温度异常(SSTA)在年代际尺度上的变化特征及其与太平洋年代际涛动(PDO)之间的关系。发现南海SSTA年代际振荡与年循环之间存在一定程度上的锁相:在冬、春季较强,而夏、秋季则较弱。此外,在过去的140多年,南海SSTA年代际振荡显著衰弱。通过与PDO指数进行相关分析发现,在年代际尺度上PDO与南海SSTA具有一定的相关性。一方面这种相关性只在20世纪前50年比较显著,这在一定程度上解释了为何南海SSTA的年代际振荡表现出衰减的趋势;另一方面,当PDO位相超前南海SSTA位相3到6个月时,两者表现出较强的相关性。进一步分析表明,PDO可能通过调控赤道东太平洋SST,从而影响南海SSTA的年代际变化。

Based on the singular spectrum analysis and the wavelet analysis, we analyzed the decadal variability of sea surface temperature anomaly （SSTA） in the South China Sea as well as its relationship with the Pacific Decadal Oscillation （PDO）. There was a so-called phase-locking relationship between the annual cycle and the decadal oscillation of SSTA, strong in winter and spring and weak in summer and autumn. The magnitude of decadal variability has evidently decreased over the past 140 years. Besides, SSTA was highly correlated to PDO at decadal time scale： firstly, significant correlation only occured in the first half of the 20th century, which accounted for the attenuation of the decadal variability of SSTA over the past years; secondly, correlation arised when PDO leaded SSTA by 3 to 6 months. Further analysis suggested that PDO was capable of indirectly modulating the SST of the eastern equatorial Pacific to influence the decadal variation of SSTA in the South China Sea.