本文利用滞后相关分析，研究了海洋再分析资料（SODA、ORAS4和 GODAS）中的 IOD-ENSO滞后遥相关关系，并与观测资料进行对比。结果显示，3套再分析资料中热带东南印度洋秋季海表温度／海表高度异常和赤道太平洋冷舌次年秋季海表温度／海表高度异常之间显著相关，与观测结果一致。在次表层，观测和再分析资料均显示，热带东南印度洋秋季海表温度异常与赤道太平洋次表层海温异常之间的显著相关关系在冬季至次年秋季沿赤道太平洋垂向剖面向东移动，并于次年夏季和秋季在冷舌区上升至海表。热带东南印度洋和赤道太平洋冷舌滞后1年的相关关系是由海洋通道机制引起的，即 IOD 事件引起印尼贯穿流流量异常，导致赤道太平洋温跃层异常，激发赤道 Kelvin 波向东传播，从而影响赤道中－东太平洋冷舌海表温度异常。观测及 SODA 与 ORAS4资料中，热带东南印度洋和赤道太平洋冷舌滞后1年的相关关系在去除 ENSO 信号后仍然显著，表明海洋通道机制是独立于 ENSO 事件的；而在 GODAS 资料中，这些显著相关关系在去除 ENSO 信号后消失。印尼贯穿流流量异常和 Niño3．4及 DMI（Dipole Mode Index）指数之间超前－滞后12个月的相关关系显示，在SODA 和 ORAS4资料中，印尼贯穿流流量同时受到 ENSO 和 IOD 的影响，与观测结果一致；而在GODAS 中，印尼贯穿流流量异常仅与 Niño3．4指数显著相关，极少受到 IOD 事件的影响，这部分解释了 GODAS 资料中去除 ENSO 信号后，IOD-ENSO 滞后遥相关关系消失的原因。%IOD-ENSO lag teleconnection in oceanic reanalysis datasets (SODA,ORAS4,and NCEP GODAS)are analyzed and compared with those in observations based on lag correlation analysis.The results show significant lag correlations between the sea surface temperature anomalies (SSTA)/sea surface height anomalies (SSHA)in the southeastern tropical Indian Ocean (STIO)in fall and those in the equatorial Pacific cold tongue in the follow-ing fall in the three datasets,which are in agreement with observations.In the subsurface,lag correlations be-tween the STIO SSTA in fall and the temperature anomalies in the equatorial Pacific vertical section show that the significant positive correlations moved eastward in the following winter through fall and outcropped at the cold tongue in the following summer and fall in both observation and assimilation datasets.The significant lag correla-tions between the STIO and the Pacific cold tongue are attribute to the oceanic channel dynamics,i.e.,the IOD induced Indonesian Throughflow transport anomalies results in thermocline anomalies in the equatorial Pacific, driving equatorial Kelvin waves to propagate eastward,thereby contributing to the SSTA in the central-eastern Pacific cold tongue.These significant lag correlations are robust even if the ENSO signal is removed in the SODA and ORAS4 datasets,which are in agreement with those in the observations,suggesting that the oceanic channel dynamics are independent of ENSO.In comparison,the significant lag correlations have disappeared if the ENSO signal is regressed out in the GODAS dataset.Lag correlations between the Indonesian Throughflow (ITF)volume transport anomalies and the Niño3.4/DMI indices with lag time from -12 to 12 months suggest significant influ-ences of both ENSO and IOD events on the ITF transport in the SODA and ORAS4 datasets,consistent with the analyses of observations.The ITF transport anomalies,however,shows significant correlation only with Niño3.4 indices in the GODAS dataset,suggesting that the ITF transport is poorly dominated by the IOD anomalies in the GODAS.This explains why the lag correlation of IOD-ENSO teleconnection disappears at one year time lag if EN-SO signal was removed in the GODAS dataset.
展开▼
