Pattern asymmetry in extreme Indian Ocean dipoles shapes marine heat-height compound extremes around coastal Indonesia

Extreme Indian Ocean dipole events (EXIODs) exert pronounced climate impacts both regionally and globally, which are closely associated with their sea surface temperature anomalies (SSTAs). Here we find an evident asymmetry in SSTA patterns between the positive (EXpIOD) and negative (EXnIOD) phases of the EXIOD. Specifically, the warm SSTA center of the EXnIOD eastern pole is confined south of Java, whereas the cold pole during EXpIODs is primarily located off Sumatra. Diagnoses with model experiments further reveal that the pattern asymmetry is attributed to the non-uniformly distributed nonlinear vertical heat advection and latent heat flux anomalies along the Sumatra–Java coasts. Due to pattern asymmetry, more frequent and intense marine heatwaves and extreme sea level rise events induced by EXnIODs occur along the Java coast. However, current climate models systematically underestimate the degree of pattern asymmetry and its influences on local marine disasters, thereby challenging accurate predictions of coastal extremes. Pattern asymmetry in extreme Indian Ocean Dipoles suggests that cold sea surface temperature anomalies are prevalent around Sumatra, while warm anomalies, which lead to more severe compound heat-height extremes, are centered on Java.