Predicting Summer Precipitation in the Middle and Lower Reaches of the Yangtze River Using Winter Sea Surface Temperature Anomalies and Trends

Studying the causes of summer (June–July–August) precipitation anomalies in the middle and lower reaches of the Yangtze River (MLYR) and accurately predicting rainy season precipitation are important to society and the economy. In recent years, the sea surface temperature (SST) trend factor has been used to construct regression models for summer precipitation. In this study, through correlation analysis, winter SST anomaly predictors and the winter Central Pacific SST trend predictor (CPT) are identified as closely related to the following MLYR summer precipitation (YRSP). CPT can influence YRSP by inducing anomalous circulations over the North Pacific, guiding warm and moist air northward, and inhibiting the development of the anomalous anticyclone over the Northwest Pacific. This has improved the predictive skill of the seasonal regression model for YRSP. After incorporating the CPT, the correlation coefficient of the YRSP regression model improved by 40%, increasing from 0.45 to 0.63, and the root mean squared error decreased by 22%, from 1.15 to 0.90.