[AOS08-P01] Decadal climate predictability in the South Atlantic and southern Indian Oceans
Keywords:Decadal climate variability, South Atlantic, Southern Indian Ocean, Sea surface temperature
Decadal reforecast experiments in which only the model SST is initialized with the observed SST show moderately high skills in predicting the decadal SST variability in the southern Indian Ocean, in particular, the Agulhas Return Current region. This is mostly due to reasonable representation of eastward-propagating decadal SST anomalies from the South Atlantic, suggesting that the SST-nudging initialization may perform well in the regions where the local air-sea interaction takes place on decadal timescale. On the other hand, the decadal SST variability in the South Atlantic is more skillfully predicted in the other experiments in which both the SST and subsurface ocean temperature/salinity in the model are initialized with the observation. Analysis of upper-ocean heat content reveals that a significant improvement of meridional ocean heat transport from the subtropics leads to skillful prediction of decadal SST variability, particularly in the Southwest Atlantic. These results demonstrate potential roles of subsurface ocean assimilation in the skillful prediction of decadal climate variability over the South Atlantic.