Multi-decadal modulation of the El Niño–Indian monsoon relationship by Indian Ocean variability
Multi-decadal modulation of the El Niño–Indian monsoon relationship by Indian Ocean variability
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DOI：
10.1088/1748-9326/6/3/034006
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发表时间：
2011-07
影响因子：
6.7
通讯作者：
C. Ummenhofer;A. Sen Gupta;Yue Li;A. Taschetto;M. England
中科院分区：
文献类型：
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作者：
C. Ummenhofer;A. Sen Gupta;Yue Li;A. Taschetto;M. England
研究了1877-2006年印度太平洋气候变率的主要模态对印度夏季风强度的调制作用。特别探讨了印度洋条件对El Niño-Southern涛动（ENSO）与印度季风之间关系的影响。利用对过去130年ENSO和印度洋偶极子（IOD）事件的扩展分类和再分析，我们扩展了以前的年际工作，表明印度洋条件的变化也在年代际尺度上调节ENSO -印度季风关系。El Niño事件经常伴随着显著减少的印度季风和广泛的干旱条件，这是由于与纬向Walker环流下降分支的转移相关的异常沉降。然而，对于与正IOD （pIOD）事件同时发生的El Niño事件，印度洋条件通过加强印度次大陆的水汽辐合来对抗El Niño引起的干旱沉降，从而导致平均季风季节。El Niño和pIOD事件的独立和联合频率的年代际调制与20世纪初观测到的El Niño-Indian季风关系的增强以及最近El Niño-Indian季风关系的明显减弱相一致。
The role of leading modes of Indo-Pacific climate variability is investigated for modulation of the strength of the Indian summer monsoon during the period 1877–2006. In particular, the effect of Indian Ocean conditions on the relationship between the El Niño–Southern Oscillation (ENSO) and the Indian monsoon is explored. Using an extended classification for ENSO and Indian Ocean dipole (IOD) events for the past 130 years and reanalyses, we have expanded previous interannual work to show that variations in Indian Ocean conditions modulate the ENSO–Indian monsoon relationship also on decadal timescales. El Niño events are frequently accompanied by a significantly reduced Indian monsoon and widespread drought conditions due to anomalous subsidence associated with a shift in the descending branch of the zonal Walker circulation. However, for El Niño events that co-occur with positive IOD (pIOD) events, Indian Ocean conditions act to counter El Niño’s drought-inducing subsidence by enhancing moisture convergence over the Indian subcontinent, with an average monsoon season resulting. Decadal modulations of the frequency of independent and combined El Niño and pIOD events are consistent with a strengthened El Niño–Indian monsoon relationship observed at the start of the 20th century and the apparent recent weakening of the El Niño–Indian monsoon relationship.