东印度洋-西太平洋暖池的年代际变化特征研究

Interdecadal Variability of the Indo-Pacific Warm Pool

采用1958～2002年海洋同化资料SODA（Simple Ocean Data Assimilation）的海温场，定义了东印度洋。西太平洋永久性暖池（简称印．太暖池）指数，即不随季节变化的27．5℃等温面所包含的〉27．5℃的暖水体积或强度，并采用功率谱和小波分析的方法研究了其周期变化特征。结果表明，印度洋暖池和西太平洋暖池均具有显著的准10a的周期振荡和1976～1986年前后的年代际突变特征，暖池由1976年前的“冷”暖池转变为1986年后的“热”暖池；暖池指数的季节循环也存在显著的年代际突变特征，特别是西太平洋暖池在异常暖年代其季节变化还呈现出明显的增暖趋势；暖池三维结构的年代际变化主要表现为在暖年代热带南印度洋暖水的向西向南扩张和西太平洋暖池东边界的向东及北边界的向北扩张，暖异常主要分布在60m以浅的上混合层中暖池的东边界区域，而其下面的温跃层内则为更强的异常降温，垂向上表现出上暖下冷的斜压模态结构，而温跃层和混合层深度的变化在不同暖池区则有不同的特点，表明东印度洋暖池和西太平洋暖池的年代际变化可能由不同的机制引起，尚需进一步分析其海洋动力学和热力学过程。

By using the sea temperature data of SODA（Simple Ocean Data Assimilation） during 1958～2002, the permanent Indo-Pacific warm pool （IPWP） index was defined as the volume or intensity of warm waters enclosed by the 27.5 ℃ isotherm invariable with seasons. The quasi-periodic variation of the IPWP was investigated by power analysis and wavelet analysis. The results show that the IPWP had significant decadal variability of a quasi-10-year periodic oscillation and interdecadal regime shift around 1976- 1986. The IPWP turned from a ＂cold＂ warm pool before 1976 to a ＂warm＂ pool after 1986. The seasonal cycle of the IPWP index also has interdecadal variability. The decadal variability of the three dimensional structure of the IPWP shows that warm water expands northward and eastward in the Pacific and southwestward in the tropical southern Indian Ocean. Positive sea temperature anomalies （STAs） mainly exist in the upper mixing layer above 60 m and strong negative STAs in the lower thermocline layer, indicating a baroclinic mode structure. The undulations of the mixing layer and thermocline depth appear different in the eastern Indian Ocean warm pool, western part of the Pacific warm pool and the eastern part of the Pacific warm pool, implying different mechanisms in different warm pool regions, which is yet to be studied focusing on the oceanic dynamics or thermodynamics processes.