The contribution of boreal spring South Pacific atmospheric variability to the El Niño occurrence

Qingye Min, Renhe Zhang
2020 Journal of Climate  
Despite the fact that great efforts have been made to improve the prediction of El Niño events, it remains challenging because of limited understanding of El Niño and its precursors. This research focuses on the influence of South Pacific atmospheric variability on the development of the sea surface temperature anomaly (SSTA) in the tropical Pacific. It is found that as early as in the boreal spring of El Niño years, the sea level pressure anomaly (SLPA) shows a configuration characterized by
more » ... characterized by two significant negative anomaly centers in the north and a positive anomaly center in the south between the subtropics and high latitudes in South Pacific. Such anomalous SLPA pattern becomes stronger in the following late boreal spring and summer associated with the strengthening of westerly anomalies in the tropical Pacific, weakening the southeasterly trade winds and promoting the warming of tropical eastern Pacific, which is conductive to the development of El Niño events. It is demonstrated that the SLPA pattern in boreal spring revealed in this study is closely associated with boreal summer South Pacific Oscillation (SPO) and South Pacific meridional mode (SPMM). As a precursor in boreal spring, the prediction skill of South Pacific SLPA in boreal spring for the SSTA in eastern equatorial Pacific is better than that of SPMM. This study is helpful to deepen our understanding of the contribution of South Pacific extratropical atmospheric variability to the El Niño occurrence.
doi:10.1175/jcli-d-20-0122.1 fatcat:icmbv4wvwbeeheeqz2rwqxkdce