Disentangling ENSO- and ITCZ-related hydroclimate signals from replicated stalagmite multiproxy over the past 2500 years

Understanding the influence of El Niño–Southern Oscillation (ENSO) on Asian summer monsoon (ASM) precipitation is complicated by the confounding effects of the Intertropical Convergence Zone (ITCZ) and the inherent spatial heterogeneity of ASM rainfall. Here, we present replicated, high-resolution multiproxy records from two coeval stalagmites in central China, spanning the past 2500 years. Principal component analysis (PCA) of these proxies separates two dominant precipitation signals: PC1_All captures the ENSO-related precipitation, as evidenced by the East Asia–Pacific pattern during the Medieval Climate Anomaly (MCA); PC2_All represents the ITCZ-related precipitation, which is controlled by the ASM intensity. Furthermore, we found that a zonal tripole pattern of ASM rainfall during the MCA is linked to the North Atlantic Oscillation (NAO) and the Western Pacific Subtropical High (WPSH), modulated by ENSO. Our findings reveal a similarly ENSO-related rainfall pattern between the MCA and modern era, highlighting the pivotal role of replicated stalagmite multiproxy for refining regional hydroclimate reconstructions.