Seasonal Evolution of Dominant Modes in South Pacific SST and Relationship with ENSO

Seasonal Evolution of Dominant Modes in South

Pacific SST and Relationship with ENSO

LI Gang;LI Chongyin;TAN Yanke;BAI Tao

【期刊名称】《大气科学进展（英文版）》 【年(卷),期】2012(029)006

【摘要】A season-reliant empirical orthogonal function (S-EOF) analysis was applied to the seasonal mean SST anomalies (SSTAs) based on the HadISST1 dataset with linear trend removed at every grid point in the South Pacific (60.5° 19.5°S,139.5°E-60.5°W) during the period 1979-2009.The spatiotemporal characteristics of the dominant modes and their relationships with ENSO were analyzed.The results show that there are two seasonally evolving dominant modes of SSTAs in the South Pacific with interannual and interdecadal variations; they account for nearly 40％ of the total variance.Although the seasonal evolution of spatial patterns of the first S-EOF mode (S-EOF1) did not show remarkable propagation,it decays with season remarkably.The second S-EOF mode (S-EOF2) showed significant seasonal evolution and intensified with season,with distinct characteristics of eastward propagation of the negative SSTAs in southern New Zealand and positive SSTAs southeast of Australia.Both of these two modes have significant relationships with ENSO.These two modes correspond to the post-ENSO and ENSO turnabout years,respectively.The S-EOF1 mode