文献类型：期刊文献

英文题名：Impacts of onset Time of El Ni?o events on summer rainfall over southeastern australia during 1980-2017

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

机构：[1] South China Sea Institute of Marine Meteorology, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang, 524088, China

年份：2019

卷号：10

期号：3

外文期刊名：Atmosphere

收录：EI(收录号：20191306706735)、Scopus(收录号：2-s2.0-85063438628)

语种：英文

外文关键词：Atmospheric pressure - Climatology - Oceanography - Surface waters - Water vapor

外文摘要：El Ni?o-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 Ni?o on summer rainfall over southeastern Australia. Summer rainfall tended to be lower than normal in austral autumn El Ni?o events during December-January-February (DJF) and higher than normal in austral winter El Ni?o events, in 1980-2017. During autumn El Ni?o events, theWalker 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° E-170° 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 Ni?o 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 Ni?o may be a useful metric for improving the low predictive skill of southeastern Australian summer rainfall. ? 2019 by the authors.