Based on multiple observational precipitation products, the ocean dataset from the Met Office Hadley Centre and the ERA5 reanalysis dataset from 1949 to 2022, this study investigates the interdecadal relationship between Indian Ocean Dipole (IOD) and the following summer precipitation over China. It increased first and then decreased from 1949 to 2021. During the following summer, the positive IOD-related sea surface temperature anomalies over the Indian Ocean cause a low-level anomalous anticyclone in the Northwest Pacific through the Matsuno-Gill pattern. Before the mid-1980s, such positive IOD–induced atmospheric circulation anomalies were weak, and they had no significant influence on the following summer precipitation over China. However, during the late 1980s to the early 2000s, the abnormal downward motion and anomalous Philippine anticyclone extended westward covering Southern China, which led to less precipitation over Southern China. At the same time, the tropical water vapor is transported along the northwest flank of the strengthened Western Pacific Subtropical High (WPSH) to the middle and lower reaches of the Yangtze River Valley, resulting in more precipitation there. But in the last ten years, the positive IOD–induced atmospheric circulation anomalies are weak, and exert little influence on following summer precipitation over China. This interdecadal variation is related to the change of El Niño-Southern Oscillation and IOD relationship under the asymmetric response of Pacific Decadal Oscillation (PDO) to the Walker Circulation anomaly.
 

Indian Ocean Dipole,El Niño-Southern Oscillation,Pacific Decadal Oscillation,Interdecadal Variation,Summer Precipitation over China