Evolution of Summer Precipitation Quasi-Biennial Oscillation in Eastern China

The evolution of summer rainfall quasi-biennial oscillation (TBO) is studied over eastern China using monthly mean rainfall data of China 160 stations from China Meteorological Administration. The maximum entropy spectral analysis and the relative maximum entropy spectral analysis denote that the summer rainfall in eastern China has a marked TBO signal, the areas with high values distribute basically like a belt, and the variance maximum value centers are located in the Yangtze-Huaihe valley and the south littoral. Based on Rotated EOF analysis (REOF) of summer rainfall TBO, eastern China is divided into 7 sections including Northeast China, the Hetao basin, the Huaihe River basin, the Yangtze River basin, western South China, centre South China and eastern South China. The further study shows: (1) the eastern China summer rainfall amplitude possesses TBO features. (2) The summer rainfall TAO has different evolutions and interdecadal features for different sections. TBO is distinct in the Huaihe River basin, the Yangtze River basin and central South China; the TBO signal is weak in western South China and Northeast China; TBO was marked in the Hetao basin before the 1990s, but after the 1990s TBO weakened gradually; TBO was remarkable in eastern South China before the 1970s and it weakened after the 1970s. (3) The Huaihe River basin is the transition zone from south to north over eastern China, and is also the sensitive area to summer rainfall TBO in eastern China.