A Preliminary Attempt On Decadal Prediction of The East Asian Summer Monsoon

The East Asian summer monsoon (EASM) is one of the major synoptic systems that affect the summer climate in China. The anomaly of the EASM is closely related to the occurrence of droughts and floods in China. Decadal prediction of the EASM is of great significance, yet few attempts have been made by far. This study represents a preliminary attempt that uses the decadal increment (DI) method to predict the decadal variability of the EASM. The 3-year increment of the decadal variability is used as the predictand, and predictors are selected from the previous circulation and external forcing. The predicted increment is combined with the observation three years ago to get the final prediction result. The results of cross validation and independent hindcast show that the decadal increment method can well predict decadal variability of the EASM during the recent century. In particular, the decadal regime shifts of the EASM are accurately captured. The decadal variability of the EASM in 2021 is further predicted with two previous predictors of the leading 4-year summer DI of the South Indian Ocean and the DI of the East Siberian Sea sea ice cover. The real-time prediction results show that the chance for the occurrence of strong decadal EASM would be rare in 2021 and 2022. The method developed in the present study provides a new approach for decadal prediction of the EASM.