The cooperative impacts of the El Niño–Southern Oscillation and the Indian OceanDipole on the interannual variability of autumn rainfall in China
The cooperative impacts of the El Niño–Southern Oscillation and the Indian OceanDipole on the interannual variability of autumn rainfall in China
复制标题
厄尔尼诺南方涛动与印度洋偶极子对我国秋季降水年际变化的协同影响
DOI：
10.1002/joc.4475
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Weiqiang Wang
中科院分区：
文献类型：
--
作者：
Kang Xu;Congwen Zhu;Weiqiang Wang
厄尔尼诺-南方涛动（ENSO）和印度洋偶极子（IOD）是高度协同的海气相互作用，极大地影响了中国降雨的年际变化。本研究根据1951-2010年收集的数据分析，揭示了ENSO和IOD对中国北方秋季降水异常可能产生的协同影响。我们的结果表明，ENSO 和 IOD 联合事件的正相位可能会导致西北太平洋 (WNP) 地区出现异常低层反气旋，同时加强东亚急流 (EAJS) 南移。西南风输送的水分供应增加，增加了华南地区的秋季降雨量。但在负位相中，中南半岛和西北西北地区的异常气旋和反气旋之间出现南风异常，随着减弱的东亚风向北移，将更多的水汽带入黄土高原地区，导致该地区秋季降雨量增加。值得注意的是，负 IOD 在对 LP 秋季降雨异常的协同影响中起着重要作用，因为与纯拉尼娜的影响相比，相关的异常低层气旋向西移动。秋季降水对ENSO和IOD正负相位的区域不对称响应可能是由于西北部地区低层环流和高层EAJS经向移动的不同响应所致。结果表明，ENSO 和 IOD 联合引起热带印度太平洋海面温度（SST）的异常纬向梯度，从而改变印度太平洋暖池上空的对流异常，从而通过罗斯贝波响应进一步影响上层和下层大气环流。
The El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) are high degree synergic air–sea interactions greatly affecting the interannual variability of rainfall in China. This study reveals the possible cooperative impacts of the ENSO and IOD on boreal autumn rainfall anomalies in China, on the basis of data analysis collected during 1951–2010. Our results suggest that the positive phase of the combined ENSO and IOD events may result in an anomalous lower-level anticyclone over the western North Pacific (WNP) region, with a southward shift of the strengthened East Asian jet stream (EAJS). An enhanced moisture supply is transported to increase autumn rainfall over southern China by the southwesterly winds. In the negative phase, however, southerly anomalies are observed between the anomalous cyclone and anticyclone over the Indo-China Peninsula and the WNP, which carry more moisture to the Loess Plateau (LP) area with a northward shift of the weakened EAJS, leading to an increase of autumn rainfall in this area. Note that the negative IOD plays an important role in the cooperative influences on the autumn rainfall anomalies over the LP in that the associated anomalous lower-level cyclone shifts westward compared to the impacts of the pure La Niña. The regional asymmetric responses of autumn rainfall to the positive and negative phases of the ENSO and IOD could be attributed to the different responses of lower-level circulation over WNP and the meridional shift of the upper-level EAJS. Results demonstrate that the combined ENSO and IOD induce an anomalous zonal gradient of sea surface temperature (SST) over the tropical Indo-Pacific Ocean to alter the convection anomalies over the Indo-Pacific warm pool that further affect the upper and lower atmospheric circulations by means of a Rossby wave response.