Observed modes of sea surface temperature variability in the South Pacific region
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The South Pacific (SP) region exerts large control on the climate of the Southern Hemisphere at many times scales. This paper identifies the main modes of interannual sea surface temperature (SST) variability in the SP which consist of a tropical-driven mode related to a horseshoe structure of positive/negative SST anomalies within midlatitudes and highly correlated to ENSO and Interdecadal Pacific Oscillation (IPO) variability, and another mode mostly confined to extratropical latitudes which is characterized by zonal propagation of SST anomalies within the South Pacific Gyre. Both modes are associated with temperature and rainfall anomalies over the continental regions of the Southern Hemisphere. Besides the leading mode which is related to well known warmer/cooler and drier/moister conditions due to its relationship with ENSO and the IPO, an inspection of the extratropical mode indicates that it is associated with distinct patterns of sea level pressure and surface temperature advection. These relationships are used here as plausible and partial explanations to the observed warming trend observed within the Southern Hemisphere during the last decades.
KeywordsSouth Pacific Southern Hemisphere warming IPO ENSO CEOF analysis
The authors would like to thank Scott Power for his comments on an earlier version of the manuscript and the two anonymous reviewers whose suggestions led to a substantial improvement of the paper. This study was supported by Grants UBACyT-20020100100803, UBACyT-20020120300051, PIP-11220120100586 and the SPECS (GA 308378) EU-funded Project. JG-S was partially supported by the H2020-funded MSCA-IF-EF DPETNA project (GA No. 655339). The authors acknowledge the Red Española de Supercomputación (RES) and PRACE for awarding access to MareNostrum 3 at the Barcelona Supercomputing Center through the HiResClim project. The support of Virginie Guémas and Oriol Mula-Valls at the Barcelona Supercomputing Center is warmly appreciated.
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