Dynamic-Analogue Correction of the Decadal Change of East Asian Summer Precipitation in the Late 1990s

This paper systematically evaluates the deviations that appear in the hindcasts of the East Asian summer precipitation (EASP) decadal change in the late 1990s in two global coupled models (BCC-CGCM and BCC-CSM). The possible causes for the deviations between the model hindcasts and observations are analyzed. The results show that the hindcasts of EASP by BCC-CGCM and BCC-CSM deviate from observations, with the anomaly correlation coefficient (ACC) being -0.01 and -0.09 for the two models, respectively. The SST anomalies in North and West Pacific and the SST index values predicted by the two models also deviate from the observations, indicating that inconsistent SST fields may be the key factor leading to the deviation in the prediction of the EASP decadal shift. Thus, a dynamic-analogue scheme is proposed to correct the precipitation hindcasts by using SSTs, where SST and EASP are highly correlated, to select historical analogue cases. Cross validations show that the average ACC of the temporal-latitude distribution of the EASP between the corrected hindcasts and observations is 0.18 for BCC-CGCM and 0.02 for BCC-CSM; both are much higher than the uncorrected hindcasts. Applying the dynamic-analogue correction scheme in both models successfully improves prediction of the EASP decadal change in the late 1990s.