Enhanced Influence of Central Equatorial Pacific SST on East Asian Midsummer Precipitation After the 1990s

Abstract Since the 1990s, the frequency of anomalous warming events in the central equatorial Pacific has increased significantly. Associated with this trend, the Pacific‐Japan (PJ) pattern and the Northwest Pacific subtropical high (WNPSH) have undergone an interdecadal shift. Whether a similar shift occurs in the relationship between central equatorial Pacific sea surface temperature (SST) and East Asian midsummer precipitation has not yet been systematically and thoroughly investigated. Based on three‐pattern decomposition of the global atmospheric circulation method, this study elucidates the physical mechanisms underlying the interdecadal shift in the relationship between central equatorial Pacific SST and East Asian midsummer precipitation. Observational and modeling results demonstrate that since 1993, cold anomalies in the central equatorial Pacific have reinforced the Walker circulation. The intensified ascending branch over the Maritime Continent (MC) shifted northwestward, enhancing local convective activity and precipitation while releasing latent heat to excite a poleward‐propagating Rossby wave train. Subsequently, this Rossby wave train induces anomalous regional meridional circulation over East Asia, modulating local vertical motion and the intensity and position of the Northwest Pacific anticyclone (WNPAC). Ultimately, these coordinated changes in moisture transport and vertical motion shape the characteristic tripolar precipitation pattern over East Asia. These results offer predictive implications for the distribution of classic tripolar precipitation pattern in eastern China, underscoring the critical role of tropical air‐sea interaction in East Asian midsummer climate variability.