文献类型：期刊文献

英文题名：Impacts of Onset Time of El Nino Events on Summer Rainfall over Southeastern Australia during 1980-2017

作者：Fan, Lingli[1];Xu, Jianjun[1];Han, Liguo[1]

机构：[1]Guangdong Ocean Univ, Coll Ocean & Meteorol, South China Sea Inst Marine Meteorol, Zhanjiang 524088, Peoples R China

年份：2019

卷号：10

期号：3

外文期刊名：ATMOSPHERE

收录：SCI-EXPANDED(收录号：WOS:000464157700002)、、WOS

基金：This study was funded by National Key Research and Development Program of China with No 2018YFC1506002.

语种：英文

外文关键词：austral autumn El Nino; winter El Nino; southeastern Australia; summer rainfall

外文摘要：El Nino-Southern Oscillation (ENSO) has large impacts on Australia's rainfall. A composite analysis technique was utilized to distinguish the impact of onset time of El Nino on summer rainfall over southeastern Australia. Summer rainfall tended to be lower than normal in austral autumn El Nino events during December-January-February (DJF) and higher than normal in austral winter El Nino events, in 1980-2017. During autumn El Nino events, the Walker circulation and meridional cells served as a bridge, linking the warmer sea surface temperature (SST) in the eastern equatorial Pacific (EEP) and lower summer rainfall over southeastern Australia. This physical process can be described as follows: During DJF, a positive SST anomaly in the EEP was concurrent with anomalous downdraft over southeastern Australia via zonal anomalous Walker circulation, meridional anomalous cells along 170 degrees E-170 degrees W, and a Pacific South American (PSA) teleconnection wave train at 500 hPa. In addition, an anomalous convergence at 200 hPa depressed the convection. Meanwhile, an 850 hPa abnormal westerly was not conducive to transport marine water vapor into this area. These factors resulted in below-normal rainfall. During winter El Nino events, a positive SST anomaly in the central equatorial Pacific (CEP) and the changes in Walker circulation and meridional cells were weaker. The PSA teleconnection wave train shifted westward and northward, and there was a low-level anomalous ascent over southeastern Australia. At the western flank of the anomalous anticyclone, northerly transported water vapor from the ocean to southeastern Australia resulted in a sink of water vapor over this area. The development of low-level convective activity and the plentiful water vapor supply favored more rainfall over southeastern Australia. Onset time of El Nino may be a useful metric for improving the low predictive skill of southeastern Australian summer rainfall.