Decadal Prediction of Summer Precipitation in Eastern China in <scp>DCPP</scp> Models: Skill Evaluations and Potential Prediction Sources

ABSTRACT Precipitation decadal prediction is of great significance for the allocation and utilisation of water resources and the sustainable development of society. However, the dynamical decadal predictability of East Asian summer precipitation remains unclear. This study evaluates the decadal prediction of summer precipitation in eastern China using the Decadal Climate Prediction Project (DCPP) of the Coupled Model Intercomparison Project Phase 6 (CMIP6). Overall, the multi‐model ensemble mean shows weak prediction skill over eastern China. However, the model of CanESM5 outperforms other models and exhibits superior skill in predicting summer precipitation over the mid‐to‐low reaches of the Yangtze River (MLRYR) in the 2‐ to 5‐year‐lead predictions. This model shows the highest correlation coefficient of 0.7 with the observed MLRYR summer precipitation index, successfully reproducing its significantly increasing trend and variations after removing the long‐term trend. The skilful decadal predictions of the MLRYR summer precipitation are possibly rooted in the skilful predictions of the tropical eastern Pacific sea surface temperature (SST) anomaly and its influence on the summer rainfall over the MLRYR. Among the used models, only the CanESM5 skilfully predicts the decadal variability in tropical eastern Pacific SST anomaly. The decadal warming in the tropical eastern Pacific SST is associated with a weakened Walker circulation and an anomalous anticyclone over the western North Pacific, consistent with observations. Consequently, more‐than‐normal summer precipitation is observed over the MLRYR. Accordingly, the decadal variation in the tropical eastern Pacific SST anomaly could be regarded as a potential source for the decadal prediction of the MLRYR summer precipitation.