MJO Affects the Monsoon Onset Timing Over the Indian Region
MJO Affects the Monsoon Onset Timing Over the Indian Region
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DOI：
10.1029/2018gl078804
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发表时间：
2018-09
影响因子：
5.2
通讯作者：
S. Taraphdar;Fuqing Zhang;L. Leung;Xingchao Chen;O. Pauluis
中科院分区：
文献类型：
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作者：
S. Taraphdar;Fuqing Zhang;L. Leung;Xingchao Chen;O. Pauluis
本文通过对1979-2016年的观测资料进行时空滤波和合成分析，研究了Madden-Julian振荡(MJO)与南亚夏季风爆发之间的联系。我们确定了决定夏季风爆发时间的两个主要因素：与季节转换有关的背景条件和与活跃的MJO有关的季节内变化。背景条件在爆发日期之前在西印度洋经历了两到三候的急剧季节转换，而典型的季风爆发通常与热带MJO湿位相在印度洋上空的到来有关，这可能是由于MJO发起的向东传播的西风异常的推动。相反，在气候学平均爆发日期期间，与强MJO的先行干相相关的大气环流可能导致季风爆发的延迟。
This study examines the linkage between the Madden‐Julian oscillation (MJO) and the South Asian summer monsoon onset through spatiotemporal wave‐filtering and composite analyses of observational data sets during 1979–2016. We identify two major factors in determining the summer monsoon onset timing: the background conditions associated with seasonal transitions and the intraseasonal variations associated with an active MJO. The background conditions undergo sharp seasonal transition over the western Indian Ocean two to three pentads before the onset dates, while a typical monsoon onset is often associated with the arrival of the wet phase of the tropical MJO over the Indian Ocean, likely due to the promotion by the MJO‐initiated eastward propagating westerly wind anomaly. Conversely, the atmospheric circulation associated with the leading dry phase of a strong MJO during the climatological mean onset dates may lead to a delayed monsoon onset.