The relationship between the interdecadal variability of East Asian summer monsoon's movement and the spatial distribution pattern of the summer rainfall in East China

Using daily rainfall measurements from 740 stations across China and European Centre for Medium-Range Weather Forecasts (ECMWF) upper air reanalysis daily data (1958-2001), we give out climatically characters of East Asian summer monsoon's (EASM) movement with the definition of the EASM's front, finding out that the transfer of the rain belt over East China is consistent with the advance and retreat of the EASM. By the EOF (empirical orthogonal function) analysis of the gridded EASM's index (average for the 28th-45th pentad) from 1958 to 2001 in area (105°E-150°E,15°N-55°N), it is founded that, the second mode of the EOF analysis exhibits interdecadal variations and indicate that the movement of EASM has three interdecadal abrupt changes in 1965, 1980 and 1994, respectively. Therefore, the three interdecadal abrupt changes bring the different processes of the EASM's movement and lead to the obvious change of the spatial distribution pattern of summer rainfall in East China directly, especially prior to 1965, the rainfall in the mid-lower reaches of the Yangtze River is much less than normal, while the precipitation is much more in South China, North China and Northeast China but with decreasing continuously since 1965. However, the rainfall in the mid-lower Yangtze Valley increases continually from 1980, especially from 1994 the rainfall in South China and the Yangtze Valley increases rapidly while the precipitation over North China was much less than normal. Therefore, in East China underwent from the pattern of south- drought and northern- waterlog before 1979 to south-waterlog and north- drought.