全球热带海表温度异常的主振荡型分析

POP ANALYSIS OF GLOBAL TROPICAL SSTA

用主振荡型分析方法对全球热带海表温度异常进行了研究，得到了传播型和驻波型的几种典型模态，指出ＥｌＮｉｎｏ／ＬａＮｉｎａ现象与这几种典型模态的组合有关，最显著的两个典型模态周期分别为准４ａ和准２ａ，周期相近的振荡还具有不同的空间型态，热带印度洋与太平洋４个Ｎｉｎｏ海区ＳＳＴＡ呈同位相的关系，主要表现于大洋中部，且峰值时间稍滞后于太平洋，大西洋情况类似，但ＳＳＴＡ强度较弱，峰值时间滞后于太平洋和印度洋。同时指出不应仅以某单一模态解释、模拟或预测ＥｌＮｉｎｏ／ＬａＮｉｎａ现象的时空演变，而应强调多模态相互作用，叠加、‘锁相’是造成事件循环的重要原因。ＥｌＮｉｎｏ／ＬａＮｉｎａ现象除以振荡传播为主要特征外，局地振荡也不应忽视。

POP (Principal Oscillation Pattern) study is undertaken of global tropical SSTA, obtaining propagating and standing eigenmodes, which, when combined differently, are related to the occurrence of El Nio/La Nina. It is suggested that their quasi 4 and quasi 2 year periods are salient and found that oscillations close in period are marked by different patterns. Also, results show that four Nio regions in the tropical Indian/Pacific Ocean exhibit SSTA of the same phase, mainly in the middle of the oceans, with the Pacific peak time slightly ahead; it is much the same in the Atlantic except its somewhat weaker SSTA with the peak time lagged as compared to the counterpart of the Pacific/Indian ocean; it is suggestive that the explanation, simulation and prediction of El Nio/La Nina evolution in space/time should not be based on a single eigenmode but on their interaction, with emphasis on the fact that superimposition and phase locking are important factors of the event cycle. Finally, the authors indicate that the local oscillations are worthy of consideration too.