The role of air–sea coupling on November–April intraseasonal rainfall variability over the South Pacific

Abstract We investigate the impact of resolving air-sea interaction on simulation intraseasonal rainfall variability over South Pacific using ECHAM5 atmospheric general circulation model coupled with Snow-Ice-Thermocline (SIT) ocean model. compare fully two uncoupled simulations, one forced sea surface temperature (SST) climatology and daily SST from The is reduced by 17% in increased 8% SST, suggesting role air–sea coupling variability. best simulates key characteristics dominant patterns (modes) reasonable propagation correct periodicity. spatial structure modes all three simulations very similar, dynamics atmosphere primarily generate these modes. southeastward anomalies associated leading depends upon eastward propagating Madden–Julian Oscillation (MJO) signals Indian Ocean western Pacific. Air-sea improves such as both propagations are substantially climatology. considerably improved SST; however, periodicity differs Such discrepancy attributed to changes SST-rainfall relationship weaker correlations nearly in-phase relationship, enhanced positive latent heat flux feedbacks.