Differences between dynamics factors for interannual and decadal variations of rainfall over the Yangtze River valley during flood seasons

The rainfall over the Yangtze River valley during flood seasons (June to July) shows both interannual and decadal variations. The rainfall has been increasing since 1990, showing a decadal Signal. The variations of rainfall are influenced by the multi-scale interactions in the atmosphere-ocean coupled climate system. The rainfall, SST, and circulation are analyzed with the Chinese 160 station data, and other observational/reanalysis data, respectively. The separation between the interannual and decadal variations is carried out. The key areas affecting the Yangtze rainfall are the western Pacific warm pool on the interannual time scale and the EINO3 area on the decadal time scale, respectively. The circulation anomaly associated with the interannual variation occurs in the upper troposphere whereas that associated with the decadal variation appears in the lower troposphere.