太平洋次表层海温年代际变率及其突变特征

Decadal Variability and Abrupt Change of Upper-Ocean Temperature in the Pacific

利用经验正交函数展开和滑动 t检验等方法研究了太平洋次表层海温的年代际变率特征。研究表明 ,太平洋次表层海温在 1 980年前后从上至下 ,先后经历了一次显著的年代际突变 ,而且随深度不同存在着四种不同的空间突变模态 ,这四种模态的形成与北太平洋海温异常的西南潜沉路径有着密切的联系。从北太平洋窗口区潜沉的年代际信号沿西南路径传播到副热带地区 ,在温跃层 1 60 m上下与西太平洋向东北传播的异常信号汇合。因此 ,北太平洋沿西南潜沉路径传播的年代际信号对 EN-SO的影响可能是间接的 ,而热带西南太平洋则可能扮演更为重要的角色。

An EOF analysis of the decadal variability of sea temperature anomaly fields at upper-ocean standard levels has been performed in this paper,and the abrupt change feature of sea temperature has been tested by use of movable t-test technique.The analysis detects that there was a significant inter-decadal abrupt change of temperature from the surface to different depths in the subsurface layer around 1980.At different depths in the subsurface there existed 4 types of abrupt change modes,their formation was close related to the southwestward subduction route of North Pacific sea temperature anomalies.The decadal signal subduction in the window region of the North Pacific propagated southwestwards to the subtropics, and met the anomaly siginal which propagated northeastwards from the West Pacific at about 160 meters level in the themocline.Therefore,the influence of the former on ENSO decadal variability might be indirect,the latter played a more important role.