Dynamical Seasonal Prediction of the Asian Summer Monsoon in CMA-CPSv3

This study assesses the performance of the third generation operational climate prediction system developed by the China Meteorological Administration (CMA-CPSv3) in predicting the Asian summer monsoon on seasonal time scales. The evaluation is carried out using a 20-year set of ensemble hindcast data, which provides a solid foundation for comprehensively examining the model’s predictive capability and reliability. Results from the assessment demonstrate that CMA-CPSv3 has higher predictive skill for key components of the Asian summer monsoon system, covering a wide range of crucial climatic elements. Specifically, the model performs well in predicting the location of the summer rain belt, maximum rainfall intensity and distribution, large-scale atmospheric circulation patterns, the monsoon onset progression, as well as the interannual variability of dynamic summer monsoon indices that reflect the intensity and fluctuation of the monsoon system.
Notably, the model can realistically capture the interannual variability of the western North Pacific subtropical high, a pivotal atmospheric circulation system closely associated with the position and movement of the summer rain belt over eastern China. Accurate representation of this variability lays a solid foundation for improving regional rainfall predictions. When compared with its previous version, CMA-CPSv2, the upgraded CMA-CPSv3 exhibits substantial and widespread improvements in summer precipitation prediction across the Asian continent, with particularly remarkable enhancements over eastern China, a region deeply affected by the Asian summer monsoon. Further analysis suggests that these improvements are mainly attributed to the optimized simulations of sea surface temperatures in the tropical Pacific Ocean and Indian Ocean, as well as the strengthened and more realistic ocean–atmosphere coupling processes linked to these tropical sea areas. The refined air-sea interactions enable the model to better depict the remote impacts of tropical oceans on the Asian summer monsoon system, thus elevating the overall accuracy and stability of seasonal climate predictions.