Tropical Atlantic (TA) SST variability can impact the East Asian summer monsoon (EASM). Here, we find that the interannual EASM–TA relationship exhibits an evident interdecadal variation modulated by the Interdecadal Pacific Oscillation (IPO). The EASM–TA interannual relationship is strong during the positive phase of the IPO (pIPO) but weak during the negative phase of the IPO (nIPO). The pIPO (nIPO)-related warm (cold) SST anomalies in the central tropical Pacific (CTP) intensify (weaken) the convection over the CTP. Therefore, a Matsuno–Gill response of the TA-induced CTP SST change is strong (weak) during the pIPO (nIPO) period. The strong Matsuno–Gill response excites an anomalous anticyclone over the western North Pacific (WNPAC), leading to a significantly positive EASM–TA relationship. However, the WNPAC is absent in the nIPO periods due to the weak Mastono–Gill response, suggesting an insignificant EASM–TA relationship. Understanding the IPO-modulated EASM–TA relationship helps better forecast EASM variability.

热带大西洋 (TA) 海温变化会影响东亚夏季风 (EASM)。在这里，我们发现EASM-TA年际关系表现出明显的受年代际太平洋涛动（IPO）调节的年代际变化。EASM-TA 年际关系在 IPO (pIPO) 的正向阶段很强，但在 IPO (nIPO) 的负向阶段则较弱。与pIPO（nIPO）相关的热带中部太平洋（CTP）暖（冷）海温异常增强（减弱）了CTP上空的对流。因此，在 pIPO (nIPO) 期间，TA 引起的 CTP SST 变化的 Matsuno-Gill 响应强（弱）。强烈的松野-吉尔响应激发了西北太平洋（WNPAC）上空的异常反气旋，导致 EASM-TA 显着正相关。然而，由于 Mastono-Gill 响应较弱，WNPAC 在 nIPO 期间缺席，这表明 EASM-TA 关系不显着。了解 IPO 调节的 EASM-TA 关系有助于更好地预测 EASM 变化。