南海海面高度异常与厄尔尼诺和大气环流的关系

Correlation between the sea surface height anomaly and ENSO in the South China Sea

利用经验正交函数分解和相关分析等方法分析研究了南海和赤道太平洋的海面高度异常、海面温度异常和风异常之间的相关关系。得出南海海面高度异常EOF第一模态为ENSO模态,方差贡献达到44.7%。在厄尔尼诺(El Nio)期间,整个南海海面下降,SSHA呈现不同的分布状态,本文讨论了爆发与下半年的El Nio期间南海SSHA呈现的典型分布状态。El Nio的先兆阶段南海中部为SSHA低值区,鼎盛阶段南部SSHA增大形成南高北低的分布状态,恢复阶段SSHA分布与El Nio过后是否发生La Nia密切相关。南海海面高度异常与大气环流存在明显的相关关系。El Nio期间,Hadley环流的加强使得南海东部和赤道西太平洋水交换加强,水温的降低和海水的流失使南海海面下降,Walker环流结构和强度的变化则进一步促进了南海SSH的下降。El Nio期间,南海海面高度会较常年偏低。

Using Empirical Orthogonal Function method, the SSHA, SSTA, SSUA and SSVA data in the South China Sea （SCS） and the tropical Pacific Ocean are studied. The SSHA during ENSO event can well explain that of the spatial patterns of the first EOF mode which accounts for 44.7 % of the model variance. During E1Nino pe- riod, the SSH in the whole basin of the SCS decreases and the spatial distributions of SSHA can be quite different from one to another. The SSHA minimum still occurs in the middle of the basin during the precursors phase. But during the peak phase, as the anomaly in the south increases, a tilt with larger SSHA in the south and smaller SSHA in the north is built up in the basin. While during the returning phase, the distribution of SSHA can be dif- ferent depending on whether there will be a La Nifia event after the E1 Nino. The SSHA in the SCS relates well with the atmosphere circulation. During E1 Nino period, the strengthen of Hadley cell makes the water exchange increase between the east of the SCS and the west tropical Pacific Ocean. The decrease of the sea-surface temper- ature and the loss of the sea water make the SSH fall down. The changes of the structure and intensity of the Walker cell can also count on the falling SSH. During the El Nino, the sea surface height is lower then other years.