南海海表面温度年代际异常变化特征及其与PDO的联系

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.

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

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.