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On the Differences Between the South Pacific Meridional and Quadrupole Modes
Author(s) -
Ding Ruiqiang,
Li Jianping,
Yang Ruowen,
Tseng Yuheng,
Li Yang,
Ji Kai
Publication year - 2020
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2019jc015500
Subject(s) - pacific decadal oscillation , climatology , sea surface temperature , latitude , el niño southern oscillation , environmental science , oceanography , geology , geodesy
The South Pacific quadrupole (SPQ) and South Pacific meridional mode (SPMM) are the dominant modes of South Pacific sea surface temperature (SST) variability. Both SST modes have been found to affect the occurrence of El Niño‐Southern Oscillation (ENSO) events. In this study, the authors examine the differences between the SPQ and SPMM in terms of their spatial structure, temporal variations, and impacts on ENSO using observational and Coupled Model Intercomparison Project Phase 5 (CMIP5) model data. As a local SST mode defined in the subtropical southeast Pacific, the SPMM has large‐amplitude SST anomalies (SSTAs) mainly confined in the southeast Pacific. In contrast, as a basin‐scale SST mode defined in the South Pacific basin, the SPQ has large‐amplitude SSTAs over the southeast Pacific as well as over the southwest Pacific and high‐latitude South Pacific. In addition, the SPQ has its temporal variability independent of the SPMM, and the occurrence of strong SPQ events is not always simultaneous with strong SPMM events. The SPQ is more closely linked than the SPMM to ENSO, possibly because the SPQ includes an additional component of SSTAs in the southwest Pacific and high‐latitude South Pacific. These findings suggest that compared with the SPMM, the SPQ may act as an improved precursor signal for ENSO events. The results have implications for understanding the respective roles of SSTAs over different regions of the South Pacific in influencing ENSO.