Enhanced influences of ENSO on the tropical Asian summer commencement after the late-1970s
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更新:2025-03-14 20:21:28 浏览:44次
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摘要
Monsoons have a significant impact on global climate, agriculture, and water resources, especially in Asia, where their variability directly influences the livelihoods and economies of billions of people. Understanding the mechanisms and variability of monsoon commencement is essential for improving water management strategies and ensuring the sustainability of rain-fed agricultural systems. Previous studies have explored the interdecadal variations of the tropical Asian summer monsoon commencement (TAMC) and attributed it to the sea surface temperature anomalies (SSTA) in the tropical Pacific. However, the interannual relationship between El Niño-Southern Oscillation (ENSO) and TAMC seems to be enhanced after the late-1970s, a phenomenon that has not been fully examined. Using both observation and simulation datasets, this study reveals the direct and root causes of the enhanced ENSO-TAMC relationship. The direct causes are related to the intensification of atmospheric internal processes, including the Walker circulation, the equatorial Rossby waves and the extratropical Rossby wave train. The root causes are linked to the changes of ENSO structure and the increase of ENSO variance after the late-1970s. The structural changes amplify the Walker circulation and the extratropical Rossby wave train, thereby enhancing the ENSO-TAMC relationship. Simultaneously, the increased ENSO variance enhances the Walker circulation and tropical Rossby waves, further contributing to this linkage.
关键词
Asian summer monsoon commencement,Interannual change,El Niño-Southern Oscillation,Equatorial Rossby wave,Extratropical Rossby wave train
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