Interdecadal mode and its propagating characteristics of SSTA in the South Pacific |
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| Authors: | X Wang C Li W Zhou |
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| Institution: | (1) LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China;(2) Graduate School of the Chinese Academy of Sciences, Beijing, China |
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| Abstract: | Summary This paper is to promote a further understanding of the interdecadal mode of the South Pacific. With this focus, we will specifically
aim at better understanding the difference between interannual and interdecadal SSTA modes over South Pacific. We define the
difference of the normalization area-averaged SSTA in the southern extratropical Pacific (160° W–110° W, 40° S–25° S) and
the south subpolar Pacific (150° W–110° W, 60° S–45° S) as the South Pacific interdecadal index (I
spd). It is found that the interannual mode is more coherent than the interdecadal mode in the central and eastern tropical Pacific,
and the interdecadal mode is significant only during boreal winter (DJF). The interdecadal variation of SSTA firstly occurring
in the extratropic South Pacific propagates to the western boundary of the South Pacific, then moves northeast to cross the
equator, and finally reaches the central tropic Pacific. It takes about 8 years to propagate from southeast subtropical Pacific
to the north hemisphere. The previous studies have suggested the mechanism of waves in the subsurface in the South Pacific.
Our study also highlights the Rossby waves play important roles in linkage between the extratropics-tropics South Pacific
SSTA on interdecadal time scales. Moreover, the paper shows that the interdecadal variability originated in the extrotropic
southeast Pacific is mainly induced by interannual variability in the tropic Pacific. |
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