The Influence of ENSO on the Long-Term Water Storage Anomalies in the Middle-Lower Reaches of the Yangtze River Basin: Evaluation and Analysis

Recent extreme events in the Middle-Lower reaches of the Yangtze River basin (MLYRB) are proven to be possibly linked to the El Nino-Southern Oscillation (ENSO) events as indicated by terrestrial water storage anomaly (TWSA). But the relatively short observation time of Gravity Recovery and Climate Experiment series missions (2002-2017; 2018-present) affects the robustness of the evaluation of TWSA. Here, the applicability of four long-term TWSA data sets (since 1979) in the MLYRB is evaluated first using an evaluation framework including two completely independent tests. After selecting the optimal one, we investigate the effects of ENSO on TWSA in the MLYRB at the basin, subbasin, and grid cell scales, respectively. Results show that ENSO, especially the Eastern Pacific type ENSO has had a significant impact on TWSA variations in the MLYRB and its two subbasins (the Dongting Lake basin and the Poyang Lake basin) since 1979 with correlation coefficients at 0.56-0.65 and time lags at 5-6 months. However, TWSAs in the other two subbasins (the Hanjiang River basin and the Mainstream River basin) have almost no correlation with ENSO. Further analysis reveals that compared with human activity that has a limited impact on TWSA, precipitation is one of the key inducements for regional water storage changes in these two subbasins, and the no correlation between ENSO and TWSA is mainly caused by the weak link between ENSO and precipitation. Applicability of four long-term terrestrial water storage anomaly data sets is assessed using two completely independent testsAbnormally, terrestrial water storage anomalies of two subbasins have almost no correlation with El Nino-Southern Oscillation (ENSO)This abnormality is dominated by regional precipitation's weak link with ENSO