PDO and AMO Modulation of the ENSO–Asian Summer Monsoon Teleconnection During the Last Millennium
PDO and AMO Modulation of the ENSO–Asian Summer Monsoon Teleconnection During the Last Millennium
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DOI：
10.1029/2023jd039638
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发表时间：
2023-12
期刊：
影响因子：
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通讯作者：
Na Wang;Sylvia Dee;Jun Hu;Nathan Steiger;K. Thirumalai
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作者：
Na Wang;Sylvia Dee;Jun Hu;Nathan Steiger;K. Thirumalai
观测表明，厄尔尼诺-南方涛动（ENSO）与亚洲夏季风（ASM）之间的遥相关是非平稳的。然而，由于缺乏可靠的长期观察结果，对潜在机制的了解甚少。本研究使用两种最先进的基于数据同化的上千年气候重建来研究ENSO-ASM遥相关的变化;我们研究了（多）年代际气候变率模式（即太平洋年代际振荡，PDO和大西洋年代际振荡，AMO）如何调制ENSO-ASM关系。我们的分析表明，PDO对ASM变异性的影响比AMO更明显。通过比较不同的线性回归模型，我们发现，包括PDO除了ENSO循环可以提高预测的ASM，特别是对印度夏季风。特别是，印度上空厄尔尼诺（拉尼娜）造成的干（湿）异常在PDO正（负）阶段由于复合效应而增强。然而，复合差异ENSO-ASM之间的正相和负相的PDO和AMO的关系是没有统计学意义。PDO/AMO对ENSO-ASM关系的重大影响仅发生在上个千年的有限时期内。通过利用长期的古气候重建，我们记录和询问PDO和AMO在调节ENSO-ASM关系中的非平稳性。
Observations show that the teleconnection between the El Niño‐Southern Oscillation (ENSO) and the Asian summer monsoon (ASM) is non‐stationary. However, the underlying mechanisms are poorly understood due to inadequate availability of reliable, long‐term observations. This study uses two state‐of‐the‐art data assimilation‐based reconstructions of last millennium climate to examine changes in the ENSO–ASM teleconnection; we investigate how modes of (multi‐)decadal climate variability (namely, the Pacific Decadal Oscillation, PDO, and the Atlantic Multidecadal Oscillation, AMO) modulate the ENSO–ASM relationship. Our analyses reveal that the PDO exerts a more pronounced impact on ASM variability than the AMO. By comparing different linear regression models, we find that including the PDO in addition to ENSO cycles can improve prediction of the ASM, especially for the Indian summer monsoon. In particular, dry (wet) anomalies caused by El Niño (La Niña) over India become enhanced during the positive (negative) PDO phases due to a compounding effect. However, composite differences in the ENSO–ASM relationship between positive and negative phases of the PDO and AMO are not statistically significant. A significant influence of the PDO/AMO on the ENSO–ASM relationship occurred only over a limited period within the last millennium. By leveraging the long‐term paleoclimate reconstructions, we document and interrogate the non‐stationary nature of the PDO and AMO in modulating the ENSO–ASM relationship.