【摘要】 根据SST及SOI观测资料及代用资料分析了不同时间尺度的ENSO变率 ,主要结果如下 :(1)根据ENSO有代表性的指数Nino 3 4区SST及SOI近一个半世纪的观测记录 ,ENSO变率以年际变化为主 ,集中在 3个谱段 ;2～ 3a、3～ 4a及 5～ 6a。 (2 )ENSO变率有年代际变化 ,192 0— 195 0年出现过 3～ 4a典型ENSO变率的减弱。近 5 0 0年的ENSO代用资料表明 ,每百年内至少有 1次类似的减弱。 (3)大量的代用资料如冰芯 ,树木年轮、史料等证实小冰期ENSO的变率与 2 0世纪没有很大差别。 (4 )考古资料表明大约从 5kaBPENSO才活跃起来 ,在此之前ENSO的频率很低。ENSO气候模拟研究支持了ENSO变率这种长期变化与岁差有关的观点。更多还原

【Abstract】 Irregularities in ENSO variability are examined based on instrumental observations during one and a half of century and proxy data since AD1501. Conclusions are as following: (1) observational data of Nino 3 4 SST and SOI for the last one and a half of century indicated that ENSO variability is concentrated on interannual band of the spectrum.Three picks are significant at 2～3?a, 3～4?a, and 5～6?a. (2) The series of SST and SOI showed clear interdecadal variability, for example, the “quiescent period” in 1920 1950, in which the amplitude of 3～4?a period significantly reduced. The proxy data for the last 500 years provides strong evidence that similar “quiescent period” occurred at least once in each century. (3) Proxy data, such as ice core δ 18 O, tree ring width, and documentary evidence prove that ENSO variability during the period of the Little Ice Age (AD1550—1850) was nearly the same as in the 20th century. (4) Archaeological and geo archaeological evidence indicate that ENSO was not active until 5?ka?BP. It is postulated that this long term change of ENSO variability may relate to the change of precession. Modeling study supported the speculation.更多还原