摘要
Previous studies suggest that the atmospheric precursor of E1 Nifio-Southern Oscillation （ENSO） in the extratropical Southern Hemisphere （SH） might trigger a quadrapole sea surface temperature anomaly （SSTA） in the South Pacific and subsequently influence the following ENSO. Such a quadrapole SSTA is referred to as the South Pacific quadrapole （SPQ）. The present study investigated the relationships between the atmospheric precursor signal of ENSO and leading modes of atmospheric variability in the extratropical SH [including the SH annular mode （SAM）, the first Pacific-South America （PSA1） mode, and the second Pacific-South America （PSA2） mode]. The results showed that the atmospheric precursor signal in the extratropical SH basically exhibits a barotropic wavenumber-3 structure over the South Pacific and is significantly correlated with the SAM and the PSA2 mode during austral summer. Nevertheless, only the PSA2 mode was found to be a precursor for the following ENSO. It leads the SPQ-like SSTA by around one month, while the SAM and the PSA1 mode do not show any obvious linkage with either ENSO or the SPQ. This suggests that the PSA2 mode may provide a bridge between the preceding circulation anomalies over the extratropical SH and the following ENSO through the SPQ-like SSTA.
Previous studies suggest that the atmospheric precursor of E1 Nifio-Southern Oscillation （ENSO） in the extratropical Southern Hemisphere （SH） might trigger a quadrapole sea surface temperature anomaly （SSTA） in the South Pacific and subsequently influence the following ENSO. Such a quadrapole SSTA is referred to as the South Pacific quadrapole （SPQ）. The present study investigated the relationships between the atmospheric precursor signal of ENSO and leading modes of atmospheric variability in the extratropical SH [including the SH annular mode （SAM）, the first Pacific-South America （PSA1） mode, and the second Pacific-South America （PSA2） mode]. The results showed that the atmospheric precursor signal in the extratropical SH basically exhibits a barotropic wavenumber-3 structure over the South Pacific and is significantly correlated with the SAM and the PSA2 mode during austral summer. Nevertheless, only the PSA2 mode was found to be a precursor for the following ENSO. It leads the SPQ-like SSTA by around one month, while the SAM and the PSA1 mode do not show any obvious linkage with either ENSO or the SPQ. This suggests that the PSA2 mode may provide a bridge between the preceding circulation anomalies over the extratropical SH and the following ENSO through the SPQ-like SSTA.
基金
jointly supported by the China Special Fund for Meteorological Research in the Public Interest(Grant No.GYHY201506013)
the 973 project of China(Grant No.2012CB955200)
the National Natural Science Foundation of China for Excellent Young Scholars(Grant No.41522502)
the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA11010303)
the National Natural Science Foundation of China(Grant Nos.41575075,91437216 and 91637312)
