Diversity of intraseasonal oscillation over the western North Pacific
Diversity of intraseasonal oscillation over the western North Pacific
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DOI：
10.1007/s00382-021-05780-2
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发表时间：
2021-04
期刊：
影响因子：
4.6
通讯作者：
Hui Wang;Fei Liu;Bin Wang;Guosen Chen;W. Dong
中科院分区：
文献类型：
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作者：
Hui Wang;Fei Liu;Bin Wang;Guosen Chen;W. Dong
西北太平洋（WNP）季内振荡（ISO）是全球最强的，其预报是亚洲夏季风亚季节预报的基础。然而，我们对WNP ISO多样性的理解是有限的，这对我们的建模和预测工作提出了挑战。本文通过对ISO事件传播模式进行聚类分析，研究了观测到的WNP ISO的多样性，针对三个聚类：西向、东北向和西北向传播。西向星团存在于WNP内部，另外两个星团分别与源自赤道中部印度洋的向东北传播的雨带和横跨西太平洋和印度洋的向西北传播的偶极子有关。湿静态能（MSE）倾向对这些不同的传播主要是由于水平平流，而辐射加热主要维持了ISO的发展。背景海温（SST）和MSE异常部分决定了这种ISO多样性，特别是对于那些相似性较大的ISO。西向星团与西印度洋温暖的海温异常有关，是季节周期和内部年际-年代际变率的结合。东北向簇与寒冷的太平洋经向模态和La Niña-like型有关，而西北向簇则与相反的暖背景有关，两者都是内部变率。本研究发现的背景影响的ISO多样性对亚洲夏季风的模式模拟和亚季节预报都有帮助。
The western North Pacific (WNP) intraseasonal oscillation (ISO) is the strongest over the globe, its prediction is the cornerstone for subseasonal prediction of the Asian summer monsoon. Yet, our understanding of the diversity of the WNP ISO is limited, which challenges our modeling and prediction efforts. We study the diversity of observed WNP ISO by performing cluster analysis on propagation patterns of ISO events, targeting three clusters: westward, northeastward, and northwestward propagations. The westward cluster exists within the WNP, while the other two are related to the northeastward propagating rain band originated from the central equatorial Indian Ocean and to the northwestward propagating dipole across the western Pacific and Indian Ocean, respectively. Moist static energy (MSE) tendency contributing to these different propagations is mainly due to horizontal advection, while radiative heating mainly maintains the ISO’s development. Background sea surface temperature (SST) and MSE anomalies partly determine this ISO diversity, especially for those ISOs with large similarity. The westward cluster is related to warm SST anomalies in the western Indian Ocean, as a combination of seasonal cycle and internal interannual-to-interdecadal variability. The northeastward cluster is related to the cold Pacific Meridional Mode and La Niña-like pattern, while the northwestward cluster is related to the opposite warm background, both as the internal variability. Our finding of the background-affected ISO diversity over the WNP can be conducive to both model simulation and subseasonal prediction of the Asian summer monsoon.