An interdecadal change in the intensity of interannual variability in summer rainfall over southern China around early 1990s
An interdecadal change in the intensity of interannual variability in summer rainfall over southern China around early 1990s
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DOI：
10.1007/s00382-016-3069-8
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发表时间：
2018-04
期刊：
影响因子：
4.6
通讯作者：
Jiepeng Chen;Z. Wen;R. Wu;Xin Wang;Chao He;Zesheng Chen
中科院分区：
文献类型：
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作者：
Jiepeng Chen;Z. Wen;R. Wu;Xin Wang;Chao He;Zesheng Chen
20世纪90年代初，华南夏季降水年际变率（IIV）的强度显著增加，同时华南夏季降水的年代际增加。两个因素提出了这种年代际变化。一个是20世纪90年代初以来热带东印度洋（TEIO）海表温度（SST）IIV的年代际增长。异常暖（冷）TEIO SST触发异常上升（下降）运动和低层气旋（反气旋）环流，这反过来又导致异常下降（上升）通过异常纬向垂直环流在SC。20世纪90年代初TEIO SST异常振幅的增加导致了南半球夏季降水年际变率的增强; 20世纪90年代初以后，北大西洋涛动（NAO）和北大西洋三重SST异常的耦合模态对南半球夏季降水年际变率的影响增强。1979-1992年北大西洋海温的主导模态为条纹型，而1993-2008年北大西洋海温的主导模态为三重型。90年代初以后北大西洋海温的三重型可能对北大西洋涛动产生积极影响。与1979-1992年相比，1993-2008年南海夏季降水与北大西洋涛动的关系增强。北大西洋涛动与北大西洋海温场耦合后，通过欧亚波状序列对南海夏季降水的变率产生重要影响。
The intensity of interannual variability (IIV) in southern China (SC) summer rainfall experienced a remarkable increase in early 1990s, concurrent with the interdecadal increase in SC summer rainfall. Two factors are proposed for this interdecadal change. One is the interdecadal increase of IIV in tropical eastern Indian Ocean (TEIO) sea surface temperature (SST) after early 1990s. Anomalous warmer (cooler) TEIO SST triggers anomalous ascending (descending) motion and lower-level cyclonic (anticyclone) circulation in situ, which in turn induces anomalous descent (ascent) over SC through an anomalous meridional vertical circulation. This contributes to interannual summer rainfall variability over SC. The increase in the amplitude of TEIO SST anomalies in early 1990s led to an intensified interannual variability of summer rainfall over SC. The other is the strengthened influence of a coupled mode of the North Atlantic Oscillation (NAO) and North Atlantic triple SST anomaly on interannual variability in summer rainfall over SC after early 1990s. The leading EOF mode of the North Atlantic SST is characterized by a stripe pattern during 1979–1992, while during 1993–2008 the dominant mode of the North Atlantic SST is a triple pattern. The triple pattern of North Atlantic SST may exert positive effect on the NAO after early 1990s. Compared to the period 1979–1992, the relationship between the NAO and interannual summer rainfall over SC is enhanced during 1993–2008. The NAO coupled with North Atlantic SST triple exerts an important impact on SC summer rainfall variability through Eurasian wave-like train.